Swift 2.0 获取镜像超类属性
Swift 2.0 Get Mirrored Superclass Properties
我需要获取 class 的属性作为字典。为简单起见，我创建了一个默认实现如下的协议：
protocol ListsProperties{
func toDictionary() -> [String: AnyObject]
}
extension ListsProperties{
func toDictionary() -> [String: AnyObject] {
let mirrored_object = Mirror(reflecting: self)
var dict = [String: AnyObject]()
for (_, attr) in mirrored_object.children.enumerate() {
if let propertyName = attr.label as String! {
dict[propertyName] = attr.value as? AnyObject
}
}
return dict
}
}
我的 classes 可以符合此协议，并且可以使用 toDictionary() 方法。但是，如果我在 subclass 上使用该方法，这将不起作用，因为它只会生成在 subclass 上定义的属性，而忽略父 superclass 属性。
理想情况下，我可以找到一些方法在镜像的 superclass 上调用 toDictionary() 方法，因为这会在它自己的 superclass 上调用 toDictionary() 并且编译器说superclass 镜像不符合协议，即使 class 它正在镜像。
以下方法有效，但前提是只有一个超级class，所以还不够：
func toDictionary() -> [String: AnyObject] {
let mirrored_object = Mirror(reflecting: self)
var dict = [String: AnyObject]()
for (_, attr) in mirrored_object.children.enumerate() {
if let propertyName = attr.label as String! {
dict[propertyName] = attr.value as? AnyObject
}
}
// This is an issue as it limits to one subclass 'deep'
if let parent = mirrored_object.superclassMirror(){
for (_, attr) in parent.children.enumerate() {
if let propertyName = attr.label as String!{
if dict[propertyName] == nil{
dict[propertyName] = attr.value as? AnyObject
}
}
}
}
return dict
}
关于如何修改 toDictionary() 的默认实现以包含 superclass 属性（以及 superclass 的任何 superclasses 的属性等的任何想法)?
一个可能的解决方案是实施 toDictionary()
作为Mirror本身的一个方法，这样就可以递归遍历
到超类镜像：
extension Mirror {
func toDictionary() -> [String: AnyObject] {
var dict = [String: AnyObject]()
// Properties of this instance:
for attr in self.children {
if let propertyName = attr.label {
dict[propertyName] = attr.value as? AnyObject
}
}
// Add properties of superclass:
if let parent = self.superclassMirror() {
for (propertyName, value) in parent.toDictionary() {
dict[propertyName] = value
}
}
return dict
}
}
然后用它来实现协议扩展方法：
extension ListsProperties {
func toDictionary() -> [String: AnyObject] {
return Mirror(reflecting: self).toDictionary()
}
}
通过使用协议，您需要所有的超级classes 实现这样的协议才能使用该功能。
我会使用助手 class，这样您就可以将任何对象传递给它。
class ListsPropertiesHelper {
static func toDictionary(mirrored_object: Mirror) -> [String: AnyObject] {
var dict = [String: AnyObject]()
for (_, attr) in mirrored_object.children.enumerate() {
if let propertyName = attr.label as String! {
dict[propertyName] = attr.value as? AnyObject
}
}
if let parent = mirrored_object.superclassMirror() {
let dict2 = toDictionary(parent)
for (key,value) in dict2 {
dict.updateValue(value, forKey:key)
}
}
return dict
}
static func toDictionary(obj: AnyObject) -> [String: AnyObject] {
let mirrored_object = Mirror(reflecting: obj)
return self.toDictionary(mirrored_object)
}
}
那你就可以像这样使用了
let props = ListsPropertiesHelper.toDictionary(someObject)
如果你还想写
let props = someObject.toDictionary()
您可以使用调用助手的扩展来实现协议 class。
这是上面 toDictionary 的完整版本。
它使用方法，其中 toDictionary() 是 Mirror 的扩展
我添加了递归，因此它可以处理任何深度的 class 层次结构。
它自己获得 mirror.children >> self.super >> self.super.super .. 等
- 您也可以告诉它停止 at/not 包括一个 class 例如"NSObject"
"UIViewController"
我打算自己使用它来将我的模型对象转换为 CKRecord。
- Adv: 模型对象本身不需要知道 CKRecord
辅助方法
上面的 "helper method" 也可以工作，但因为它只是使用 Mirror 中的方法，将所有代码添加为 Mirror 的扩展也合乎逻辑。
只需将下面的所有代码粘贴到 Playground 中即可。
执行从底部代码块开始，参见：
//执行从这里开始
//: Playground - noun: a place where people can play
import UIKit
//
//http://appventure.me/2015/10/24/swift-reflection-api-what-you-can-do/
//------------------------------------------------------------------------------------------------
//TEST DATA STRUCTURES
//------------------------------------------------------------------------------------------------
//Subclasses of NSObject
//super class of ClassASwift is NSObject
//But If we scan this tree for ivars then we dont want to include NSObject
//------------------------------------------------------------------------------------------------
class ClassNSObjectA : NSObject{
var textA = "Some textA"
var numA = 1111
var dateA = NSDate()
var arrayA = ["A1", "A2"]
}
class ClassNSObjectB : ClassNSObjectA{
var textB = "Some textB"
var numB = 1111
var dateB = NSDate()
var arrayB = ["B1", "B2"]
}
class ClassNSObjectC : ClassNSObjectB{
var textC = "Some textC"
var numC = 1111
var dateC = NSDate()
var arrayC = ["C1", "C2"]
}
//------------------------------------------------------------------------------------------------
//Swift only object tree - no Root
//super class of ClassASwift is nil
//------------------------------------------------------------------------------------------------
class ClassASwift {
var textA = "A Swift"
var numA = 1111
var dateA = NSDate()
var arrayA = ["A1Swift", "A2Swift"]
}
class ClassBSwift : ClassASwift{
var textB = "B Swift"
var numB = 1111
var dateB = NSDate()
var arrayB = ["B1Swift", "B2Swift"]
}
class ClassCSwift : ClassBSwift{
var textC = "C Swift"
var numC = 1111
var dateC = NSDate()
var arrayC = ["C1Swift", "C2Swift"]
}
extension Mirror {
//------------------------------------------------------------------------------------------------
//How to scan a tree hierarchy of classes
//------------------------------------------------------------------------------------------------
/*
TASK: we want to walk the tree from a given instance back up to the root and dump the ivars using Swift reflection.
It came from a need to convert any object to CKRecord and have clean model objects for RealmDB.
with the following issues:
Some objects are Swift only - so no root object.
So we scan up the tree recursively till super is nil
Some objects have NSObject at the root.
We scan up the tree and extract the ivar but we dont want to include the ivars for NSObject
We wanted to keep our Model object as Swift as possible.
Swift only
You can use all the NSObject refection apis but only on NSObject classes so we need to only use Swift Reflection Mirror(reflecting:)
------
We could add this objectToDictionary() method as a func on
extension NSObject {
scan()
}
But this only work for subclasses of NSObject
------
Youre not allowed to have an extension on AnyObject so you cant create a swift method objectToDictionary() common to ALL Swift or NSObject Objects
Workaround: Have a common parent for our Model objects?
Change
class ClassA : NSObject{...}
class ClassASwift {...}
class ClassA : ParentOfNSObject{...}
class ClassASwift : ParentOfSwiftObject{...}
but what if I want to be able to use objectToDictionary() on ALL Swift or NSObject objects
------
-- Answer --
The purpose of this method is to scan an object hierarchy and convert it to a Dictionary or CKRecord etc.
To scan an instance we need access to Mirror and to get the objects ivars (mirror.children) and its super class ivars
Answer was to add our extension to Mirror rather than to the object itself (dont add this method as extension to NSObject or some ParentOfSwiftObject)
This is similar to a Third method - a helper class
the helperclas will just use Mirror
the method here just combines the Mirror recursion with my extract code
*/
func objectToDictionary(stopAtParentClassName : String?) -> [String: AnyObject]{
//this is extension on Mirror - self is of type Mirror not the object we're analyzing
let dict: [String: AnyObject] = objectToDictionaryForMirror(self, stopAtParentClassName: stopAtParentClassName)
return dict
}
func objectToDictionaryForMirror(mirror: Mirror, stopAtParentClassName : String?) -> [String: AnyObject]{
var dictOfIVars = [String: AnyObject]()
let classname = "\(mirror.subjectType)"
print("classname:\(classname)")
//e.g. if stopAtParentClassName is nil or "NSObject"
//stopAtParentClassName can be nil or (set and "NSObject" OR (set and not "NSbject")
let stopAtParentClassName_ = stopAtParentClassName ?? ""
if (classname == stopAtParentClassName_){
//note : not really an issue for mirror.children as NSObject has none but you can parse for other reflected elements
print("NSObject found - skipNSObjectRoot is true - SKIP this class - return empty dictionary")
}else{
//------------------------------------------------------------------------------------------------
//Not NSObject or skipNSObjectRoot is false
//------------------------------------------------------------------------------------------------
//ITERATE OVER PROPERTIES
//I included two ways to do this
//v1 - dumps the properties
//v2 - append then to a dict which is recursively appended them to outer dict
//just remove which ever one you want
//------------------------------------------------------------------------------------------------
//v1
//public typealias Child = (label: String?, value: Any)
//note its mirror.children not self.children
//dont use self.children : as you recursively call this method self.children will only reference the base instance
//mirror is the recursive mirror so scanMirror(self) >> scanMirror(self.super) >> scanMirror(self.super.super) .. stop when super is nil
for case let (label?, value) in mirror.children {
print("PROP [\(classname)] label:[\(label)] value:[\(value)]")
}
//----------------------------------------------
//v2
// Properties of this instance:
//self <=> Mirror
for property in mirror.children {
if let propertyName = property.label {
dictOfIVars[propertyName] = property.value as? AnyObject
}
}
//------------------------------------------------------------------------------------------------
//Mirror.children only returns ivar of current class
//you need to walk up the tree to get all inherited properties
//Swift object hierarchy has no root - superclassMirror() will become nil - and recursion will stop
//NSObject object hierarchy has root NSObject - superclassMirror() will inlcude this unless stopAtParentClassName is "NSObject"
//------------------------------------------------------------------------------------------------
if let superclassMirror = mirror.superclassMirror() {
let dictOfIVarsForSuperClass : [String: AnyObject] = objectToDictionaryForMirror(superclassMirror, stopAtParentClassName: stopAtParentClassName)
//merge
dictOfIVars.merge(dictOfIVarsForSuperClass)
}else{
print("class has no superclassMirror")
}
//---------------------------------------------------------------------
}
return dictOfIVars
}
}
//Used to recursively merge superclass ivar dictionary to subclasses ivar dictionary
extension Dictionary{
// https://github.com/terhechte/SourceKittenDaemon/blob/83dc62d3e9157b69530ed93b82b5aae9cd225427/SourceKittenDaemon/Extensions/Dictionary%2B.swift
mutating func merge(dictionary: Dictionary<Key, Value>) {
for (key, value) in dictionary {
self[key] = value
}
}
}
func dumpDictionary(anyObject: AnyObject, stopAtParentClassName: String?){
let mirror = Mirror(reflecting: anyObject)
//---------------------------------------------------------------------
//SCAN HIERARCHY - return info as a dict
//---------------------------------------------------------------------
let dictOfIVars = mirror.objectToDictionary(stopAtParentClassName)
print("*****************************************************")
print("*********** SCAN COMPLETE - DUMP DICT INFO***********")
print("*****************************************************")
print("dictOfIVars:\r\(dictOfIVars)")
//------------------------------------------------------------------------------------------------
//DEBUGGING - dump the returned dict
//------------------------------------------------------------------------------------------------
print("KEYS:")
//print("dictOfIVars.keys:\(dictOfIVars.keys)")
for key in dictOfIVars.keys.sort(){
print(key)
}
//------------------------------------------------------------------------------------------------
print("dictOfIVars.keys.count:\(dictOfIVars.keys.count)")
//------------------------------------------------------------------------------------------------
}
//EXECUTION STARTS HERE IF YOU PASTE IN TO PLAYGROUND
print("======================================================================")
print("START TESTS - open console below ")
print("======================================================================")
//------------------------------------------------------------------------------------------------
//NSObject class hierarchy
//------------------------------------------------------------------------------------------------
print("")
print("=====================================================================================================================")
print("========== TEST 1: recursively iterate up tree of NSObject subclasses - include root object 'NSObject' in scan")
print("=====================================================================================================================")
let instanceC : ClassNSObjectB = ClassNSObjectC()
//Dont include NSObject root in parse
dumpDictionary(instanceC, stopAtParentClassName: "NSObject")
print("")
print("=====================================================================================================================")
print("========== TEST 2: recursively iterate up tree of NSObject subclasses - DO NOT include root object 'NSObject' in scan")
print("=====================================================================================================================")
//Do include NSObject
dumpDictionary(instanceC, stopAtParentClassName: nil)
//note were only dumping mirror.children in this example and NSObject doesnt have any but added for completeness.
//could dump all sub classes of UIViewController - but not include the UIViewController class ivars
//------------------------------------------------------------------------------------------------
//Switft class hierarchy - no root class
//------------------------------------------------------------------------------------------------
print("")
print("======================================================================================================================")
print("========== TEST 3: recursively iterate up tree of Swift subclasses")
print("======================================================================================================================")
let classBSwift : ClassBSwift = ClassCSwift()
dumpDictionary(classBSwift, stopAtParentClassName: nil)
输出
======================================================================
START TESTS - open console below
======================================================================
=====================================================================================================================
========== TEST 1: recursively iterate up tree of NSObject subclasses - include root object 'NSObject' in scan
=====================================================================================================================
classname:ClassNSObjectC
PROP [ClassNSObjectC] label:[textC] value:[Some textC]
PROP [ClassNSObjectC] label:[numC] value:[1111]
PROP [ClassNSObjectC] label:[dateC] value:[2016-02-17 13:37:35 +0000]
PROP [ClassNSObjectC] label:[arrayC] value:[["C1", "C2"]]
classname:ClassNSObjectB
PROP [ClassNSObjectB] label:[textB] value:[Some textB]
PROP [ClassNSObjectB] label:[numB] value:[1111]
PROP [ClassNSObjectB] label:[dateB] value:[2016-02-17 13:37:35 +0000]
PROP [ClassNSObjectB] label:[arrayB] value:[["B1", "B2"]]
classname:ClassNSObjectA
PROP [ClassNSObjectA] label:[textA] value:[Some textA]
PROP [ClassNSObjectA] label:[numA] value:[1111]
PROP [ClassNSObjectA] label:[dateA] value:[2016-02-17 13:37:35 +0000]
PROP [ClassNSObjectA] label:[arrayA] value:[["A1", "A2"]]
classname:NSObject
NSObject found - skipNSObjectRoot is true - SKIP this class - return empty dictionary
*****************************************************
*********** SCAN COMPLETE - DUMP DICT INFO***********
*****************************************************
dictOfIVars:
["numB": 1111, "numC": 1111, "arrayB": (
B1,
B2
), "dateA": 2016-02-17 13:37:35 +0000, "dateC": 2016-02-17 13:37:35 +0000, "dateB": 2016-02-17 13:37:35 +0000, "arrayC": (
C1,
C2
), "textC": Some textC, "arrayA": (
A1,
A2
), "textA": Some textA, "numA": 1111, "textB": Some textB]
KEYS:
arrayA
arrayB
arrayC
dateA
dateB
dateC
numA
numB
numC
textA
textB
textC
dictOfIVars.keys.count:12
=====================================================================================================================
========== TEST 2: recursively iterate up tree of NSObject subclasses - DO NOT include root object 'NSObject' in scan
=====================================================================================================================
classname:ClassNSObjectC
PROP [ClassNSObjectC] label:[textC] value:[Some textC]
PROP [ClassNSObjectC] label:[numC] value:[1111]
PROP [ClassNSObjectC] label:[dateC] value:[2016-02-17 13:37:35 +0000]
PROP [ClassNSObjectC] label:[arrayC] value:[["C1", "C2"]]
classname:ClassNSObjectB
PROP [ClassNSObjectB] label:[textB] value:[Some textB]
PROP [ClassNSObjectB] label:[numB] value:[1111]
PROP [ClassNSObjectB] label:[dateB] value:[2016-02-17 13:37:35 +0000]
PROP [ClassNSObjectB] label:[arrayB] value:[["B1", "B2"]]
classname:ClassNSObjectA
PROP [ClassNSObjectA] label:[textA] value:[Some textA]
PROP [ClassNSObjectA] label:[numA] value:[1111]
PROP [ClassNSObjectA] label:[dateA] value:[2016-02-17 13:37:35 +0000]
PROP [ClassNSObjectA] label:[arrayA] value:[["A1", "A2"]]
classname:NSObject
class has no superclassMirror
*****************************************************
*********** SCAN COMPLETE - DUMP DICT INFO***********
*****************************************************
dictOfIVars:
["numB": 1111, "numC": 1111, "arrayB": (
B1,
B2
), "dateA": 2016-02-17 13:37:35 +0000, "dateC": 2016-02-17 13:37:35 +0000, "dateB": 2016-02-17 13:37:35 +0000, "arrayC": (
C1,
C2
), "textC": Some textC, "arrayA": (
A1,
A2
), "textA": Some textA, "numA": 1111, "textB": Some textB]
KEYS:
arrayA
arrayB
arrayC
dateA
dateB
dateC
numA
numB
numC
textA
textB
textC
dictOfIVars.keys.count:12
======================================================================================================================
========== TEST 3: recursively iterate up tree of Swift subclasses
======================================================================================================================
classname:ClassCSwift
PROP [ClassCSwift] label:[textC] value:[C Swift]
PROP [ClassCSwift] label:[numC] value:[1111]
PROP [ClassCSwift] label:[dateC] value:[2016-02-17 13:37:35 +0000]
PROP [ClassCSwift] label:[arrayC] value:[["C1Swift", "C2Swift"]]
classname:ClassBSwift
PROP [ClassBSwift] label:[textB] value:[B Swift]
PROP [ClassBSwift] label:[numB] value:[1111]
PROP [ClassBSwift] label:[dateB] value:[2016-02-17 13:37:35 +0000]
PROP [ClassBSwift] label:[arrayB] value:[["B1Swift", "B2Swift"]]
classname:ClassASwift
PROP [ClassASwift] label:[textA] value:[A Swift]
PROP [ClassASwift] label:[numA] value:[1111]
PROP [ClassASwift] label:[dateA] value:[2016-02-17 13:37:35 +0000]
PROP [ClassASwift] label:[arrayA] value:[["A1Swift", "A2Swift"]]
class has no superclassMirror
*****************************************************
*********** SCAN COMPLETE - DUMP DICT INFO***********
*****************************************************
dictOfIVars:
["numB": 1111, "numC": 1111, "arrayB": (
B1Swift,
B2Swift
), "dateA": 2016-02-17 13:37:35 +0000, "dateC": 2016-02-17 13:37:35 +0000, "dateB": 2016-02-17 13:37:35 +0000, "arrayC": (
C1Swift,
C2Swift
), "textC": C Swift, "arrayA": (
A1Swift,
A2Swift
), "textA": A Swift, "numA": 1111, "textB": B Swift]
KEYS:
arrayA
arrayB
arrayC
dateA
dateB
dateC
numA
numB
numC
textA
textB
textC
dictOfIVars.keys.count:12
您可以简单地遍历所有 superclassMirror 获取属性。有多少层并不重要。
var mirror: Mirror? = Mirror(reflecting: child)
repeat {
for property in mirror!.children {
print("property: \(property)")
}
mirror = mirror?.superclassMirror()
} while mirror != nil
这是我的实现
- 支持继承链
- 支持嵌套对象
- 展开选项如果 .some
- 支持带有 rawValue 的枚举
- 支持数组
.
public protocol Serializable {
func serialize() -> [String: Any]
}
extension Serializable {
public func serialize() -> [String: Any] {
var result = [String: Any]()
var enumeratingMirror: Mirror? = Mirror(reflecting: self)
while true {
guard let mirror = enumeratingMirror else { break }
for child in mirror.children {
guard let label = child.label else { continue }
switch child.value {
case let serializable as Serializable:
if case .some(let value) = optional {
result[label] = value
}
case let rawRepresentable as RawRepresentable:
result[label] = rawRepresentable.getValueAsAny()
case let optional as Optional<Any>:
if case .some(let value) = optional {
result[label] = value
}
default:
result[label] = child.value
}
}
enumeratingMirror = mirror.superclassMirror
}
return result
}
}
extension Collection where Iterator.Element: Serializable {
public func serialize() -> [[String: Any]] {
return map { [=10=].serialize() }
}
}
extension RawRepresentable {
public func getValueAsAny() -> Any {
return rawValue
}
}
用法
class BaseUser: Serializable { let id: Int = 1 }
class User: BaseUser { let name: String = "Aryan" }
let user = User()
print(user.serialize()) // {"id": 1, "name": "Aryan"}
print([user].serialize()) // [{"id": 1, "name": "Aryan"}]
我的解决方案是使用
Mirror(self, children: properties, ancestorRepresentation: Mirror.AncestorRepresentation.generated)
而不是
Mirror(representing: self)
properties 是一个 DictionnaryLiteral 对象，包含我要镜像的属性。
我需要获取 class 的属性作为字典。为简单起见，我创建了一个默认实现如下的协议：
protocol ListsProperties{
func toDictionary() -> [String: AnyObject]
}
extension ListsProperties{
func toDictionary() -> [String: AnyObject] {
let mirrored_object = Mirror(reflecting: self)
var dict = [String: AnyObject]()
for (_, attr) in mirrored_object.children.enumerate() {
if let propertyName = attr.label as String! {
dict[propertyName] = attr.value as? AnyObject
}
}
return dict
}
}
我的 classes 可以符合此协议，并且可以使用 toDictionary() 方法。但是，如果我在 subclass 上使用该方法，这将不起作用，因为它只会生成在 subclass 上定义的属性，而忽略父 superclass 属性。
理想情况下，我可以找到一些方法在镜像的 superclass 上调用 toDictionary() 方法，因为这会在它自己的 superclass 上调用 toDictionary() 并且编译器说superclass 镜像不符合协议，即使 class 它正在镜像。
以下方法有效，但前提是只有一个超级class，所以还不够：
func toDictionary() -> [String: AnyObject] {
let mirrored_object = Mirror(reflecting: self)
var dict = [String: AnyObject]()
for (_, attr) in mirrored_object.children.enumerate() {
if let propertyName = attr.label as String! {
dict[propertyName] = attr.value as? AnyObject
}
}
// This is an issue as it limits to one subclass 'deep'
if let parent = mirrored_object.superclassMirror(){
for (_, attr) in parent.children.enumerate() {
if let propertyName = attr.label as String!{
if dict[propertyName] == nil{
dict[propertyName] = attr.value as? AnyObject
}
}
}
}
return dict
}
关于如何修改 toDictionary() 的默认实现以包含 superclass 属性（以及 superclass 的任何 superclasses 的属性等的任何想法)?
一个可能的解决方案是实施 toDictionary()
作为Mirror本身的一个方法，这样就可以递归遍历
到超类镜像：
extension Mirror {
func toDictionary() -> [String: AnyObject] {
var dict = [String: AnyObject]()
// Properties of this instance:
for attr in self.children {
if let propertyName = attr.label {
dict[propertyName] = attr.value as? AnyObject
}
}
// Add properties of superclass:
if let parent = self.superclassMirror() {
for (propertyName, value) in parent.toDictionary() {
dict[propertyName] = value
}
}
return dict
}
}
然后用它来实现协议扩展方法：
extension ListsProperties {
func toDictionary() -> [String: AnyObject] {
return Mirror(reflecting: self).toDictionary()
}
}
通过使用协议，您需要所有的超级classes 实现这样的协议才能使用该功能。
我会使用助手 class，这样您就可以将任何对象传递给它。
class ListsPropertiesHelper {
static func toDictionary(mirrored_object: Mirror) -> [String: AnyObject] {
var dict = [String: AnyObject]()
for (_, attr) in mirrored_object.children.enumerate() {
if let propertyName = attr.label as String! {
dict[propertyName] = attr.value as? AnyObject
}
}
if let parent = mirrored_object.superclassMirror() {
let dict2 = toDictionary(parent)
for (key,value) in dict2 {
dict.updateValue(value, forKey:key)
}
}
return dict
}
static func toDictionary(obj: AnyObject) -> [String: AnyObject] {
let mirrored_object = Mirror(reflecting: obj)
return self.toDictionary(mirrored_object)
}
}
那你就可以像这样使用了
let props = ListsPropertiesHelper.toDictionary(someObject)
如果你还想写
let props = someObject.toDictionary()
您可以使用调用助手的扩展来实现协议 class。
这是上面 toDictionary 的完整版本。
它使用方法，其中 toDictionary() 是 Mirror 的扩展
我添加了递归，因此它可以处理任何深度的 class 层次结构。
它自己获得 mirror.children >> self.super >> self.super.super .. 等
- 您也可以告诉它停止 at/not 包括一个 class 例如"NSObject" "UIViewController"
我打算自己使用它来将我的模型对象转换为 CKRecord。
- Adv: 模型对象本身不需要知道 CKRecord
辅助方法
上面的 "helper method" 也可以工作，但因为它只是使用 Mirror 中的方法，将所有代码添加为 Mirror 的扩展也合乎逻辑。
只需将下面的所有代码粘贴到 Playground 中即可。
执行从底部代码块开始，参见：
//执行从这里开始
//: Playground - noun: a place where people can play
import UIKit
//
//http://appventure.me/2015/10/24/swift-reflection-api-what-you-can-do/
//------------------------------------------------------------------------------------------------
//TEST DATA STRUCTURES
//------------------------------------------------------------------------------------------------
//Subclasses of NSObject
//super class of ClassASwift is NSObject
//But If we scan this tree for ivars then we dont want to include NSObject
//------------------------------------------------------------------------------------------------
class ClassNSObjectA : NSObject{
var textA = "Some textA"
var numA = 1111
var dateA = NSDate()
var arrayA = ["A1", "A2"]
}
class ClassNSObjectB : ClassNSObjectA{
var textB = "Some textB"
var numB = 1111
var dateB = NSDate()
var arrayB = ["B1", "B2"]
}
class ClassNSObjectC : ClassNSObjectB{
var textC = "Some textC"
var numC = 1111
var dateC = NSDate()
var arrayC = ["C1", "C2"]
}
//------------------------------------------------------------------------------------------------
//Swift only object tree - no Root
//super class of ClassASwift is nil
//------------------------------------------------------------------------------------------------
class ClassASwift {
var textA = "A Swift"
var numA = 1111
var dateA = NSDate()
var arrayA = ["A1Swift", "A2Swift"]
}
class ClassBSwift : ClassASwift{
var textB = "B Swift"
var numB = 1111
var dateB = NSDate()
var arrayB = ["B1Swift", "B2Swift"]
}
class ClassCSwift : ClassBSwift{
var textC = "C Swift"
var numC = 1111
var dateC = NSDate()
var arrayC = ["C1Swift", "C2Swift"]
}
extension Mirror {
//------------------------------------------------------------------------------------------------
//How to scan a tree hierarchy of classes
//------------------------------------------------------------------------------------------------
/*
TASK: we want to walk the tree from a given instance back up to the root and dump the ivars using Swift reflection.
It came from a need to convert any object to CKRecord and have clean model objects for RealmDB.
with the following issues:
Some objects are Swift only - so no root object.
So we scan up the tree recursively till super is nil
Some objects have NSObject at the root.
We scan up the tree and extract the ivar but we dont want to include the ivars for NSObject
We wanted to keep our Model object as Swift as possible.
Swift only
You can use all the NSObject refection apis but only on NSObject classes so we need to only use Swift Reflection Mirror(reflecting:)
------
We could add this objectToDictionary() method as a func on
extension NSObject {
scan()
}
But this only work for subclasses of NSObject
------
Youre not allowed to have an extension on AnyObject so you cant create a swift method objectToDictionary() common to ALL Swift or NSObject Objects
Workaround: Have a common parent for our Model objects?
Change
class ClassA : NSObject{...}
class ClassASwift {...}
class ClassA : ParentOfNSObject{...}
class ClassASwift : ParentOfSwiftObject{...}
but what if I want to be able to use objectToDictionary() on ALL Swift or NSObject objects
------
-- Answer --
The purpose of this method is to scan an object hierarchy and convert it to a Dictionary or CKRecord etc.
To scan an instance we need access to Mirror and to get the objects ivars (mirror.children) and its super class ivars
Answer was to add our extension to Mirror rather than to the object itself (dont add this method as extension to NSObject or some ParentOfSwiftObject)
This is similar to a Third method - a helper class
the helperclas will just use Mirror
the method here just combines the Mirror recursion with my extract code
*/
func objectToDictionary(stopAtParentClassName : String?) -> [String: AnyObject]{
//this is extension on Mirror - self is of type Mirror not the object we're analyzing
let dict: [String: AnyObject] = objectToDictionaryForMirror(self, stopAtParentClassName: stopAtParentClassName)
return dict
}
func objectToDictionaryForMirror(mirror: Mirror, stopAtParentClassName : String?) -> [String: AnyObject]{
var dictOfIVars = [String: AnyObject]()
let classname = "\(mirror.subjectType)"
print("classname:\(classname)")
//e.g. if stopAtParentClassName is nil or "NSObject"
//stopAtParentClassName can be nil or (set and "NSObject" OR (set and not "NSbject")
let stopAtParentClassName_ = stopAtParentClassName ?? ""
if (classname == stopAtParentClassName_){
//note : not really an issue for mirror.children as NSObject has none but you can parse for other reflected elements
print("NSObject found - skipNSObjectRoot is true - SKIP this class - return empty dictionary")
}else{
//------------------------------------------------------------------------------------------------
//Not NSObject or skipNSObjectRoot is false
//------------------------------------------------------------------------------------------------
//ITERATE OVER PROPERTIES
//I included two ways to do this
//v1 - dumps the properties
//v2 - append then to a dict which is recursively appended them to outer dict
//just remove which ever one you want
//------------------------------------------------------------------------------------------------
//v1
//public typealias Child = (label: String?, value: Any)
//note its mirror.children not self.children
//dont use self.children : as you recursively call this method self.children will only reference the base instance
//mirror is the recursive mirror so scanMirror(self) >> scanMirror(self.super) >> scanMirror(self.super.super) .. stop when super is nil
for case let (label?, value) in mirror.children {
print("PROP [\(classname)] label:[\(label)] value:[\(value)]")
}
//----------------------------------------------
//v2
// Properties of this instance:
//self <=> Mirror
for property in mirror.children {
if let propertyName = property.label {
dictOfIVars[propertyName] = property.value as? AnyObject
}
}
//------------------------------------------------------------------------------------------------
//Mirror.children only returns ivar of current class
//you need to walk up the tree to get all inherited properties
//Swift object hierarchy has no root - superclassMirror() will become nil - and recursion will stop
//NSObject object hierarchy has root NSObject - superclassMirror() will inlcude this unless stopAtParentClassName is "NSObject"
//------------------------------------------------------------------------------------------------
if let superclassMirror = mirror.superclassMirror() {
let dictOfIVarsForSuperClass : [String: AnyObject] = objectToDictionaryForMirror(superclassMirror, stopAtParentClassName: stopAtParentClassName)
//merge
dictOfIVars.merge(dictOfIVarsForSuperClass)
}else{
print("class has no superclassMirror")
}
//---------------------------------------------------------------------
}
return dictOfIVars
}
}
//Used to recursively merge superclass ivar dictionary to subclasses ivar dictionary
extension Dictionary{
// https://github.com/terhechte/SourceKittenDaemon/blob/83dc62d3e9157b69530ed93b82b5aae9cd225427/SourceKittenDaemon/Extensions/Dictionary%2B.swift
mutating func merge(dictionary: Dictionary<Key, Value>) {
for (key, value) in dictionary {
self[key] = value
}
}
}
func dumpDictionary(anyObject: AnyObject, stopAtParentClassName: String?){
let mirror = Mirror(reflecting: anyObject)
//---------------------------------------------------------------------
//SCAN HIERARCHY - return info as a dict
//---------------------------------------------------------------------
let dictOfIVars = mirror.objectToDictionary(stopAtParentClassName)
print("*****************************************************")
print("*********** SCAN COMPLETE - DUMP DICT INFO***********")
print("*****************************************************")
print("dictOfIVars:\r\(dictOfIVars)")
//------------------------------------------------------------------------------------------------
//DEBUGGING - dump the returned dict
//------------------------------------------------------------------------------------------------
print("KEYS:")
//print("dictOfIVars.keys:\(dictOfIVars.keys)")
for key in dictOfIVars.keys.sort(){
print(key)
}
//------------------------------------------------------------------------------------------------
print("dictOfIVars.keys.count:\(dictOfIVars.keys.count)")
//------------------------------------------------------------------------------------------------
}
//EXECUTION STARTS HERE IF YOU PASTE IN TO PLAYGROUND
print("======================================================================")
print("START TESTS - open console below ")
print("======================================================================")
//------------------------------------------------------------------------------------------------
//NSObject class hierarchy
//------------------------------------------------------------------------------------------------
print("")
print("=====================================================================================================================")
print("========== TEST 1: recursively iterate up tree of NSObject subclasses - include root object 'NSObject' in scan")
print("=====================================================================================================================")
let instanceC : ClassNSObjectB = ClassNSObjectC()
//Dont include NSObject root in parse
dumpDictionary(instanceC, stopAtParentClassName: "NSObject")
print("")
print("=====================================================================================================================")
print("========== TEST 2: recursively iterate up tree of NSObject subclasses - DO NOT include root object 'NSObject' in scan")
print("=====================================================================================================================")
//Do include NSObject
dumpDictionary(instanceC, stopAtParentClassName: nil)
//note were only dumping mirror.children in this example and NSObject doesnt have any but added for completeness.
//could dump all sub classes of UIViewController - but not include the UIViewController class ivars
//------------------------------------------------------------------------------------------------
//Switft class hierarchy - no root class
//------------------------------------------------------------------------------------------------
print("")
print("======================================================================================================================")
print("========== TEST 3: recursively iterate up tree of Swift subclasses")
print("======================================================================================================================")
let classBSwift : ClassBSwift = ClassCSwift()
dumpDictionary(classBSwift, stopAtParentClassName: nil)
输出
======================================================================
START TESTS - open console below
======================================================================
=====================================================================================================================
========== TEST 1: recursively iterate up tree of NSObject subclasses - include root object 'NSObject' in scan
=====================================================================================================================
classname:ClassNSObjectC
PROP [ClassNSObjectC] label:[textC] value:[Some textC]
PROP [ClassNSObjectC] label:[numC] value:[1111]
PROP [ClassNSObjectC] label:[dateC] value:[2016-02-17 13:37:35 +0000]
PROP [ClassNSObjectC] label:[arrayC] value:[["C1", "C2"]]
classname:ClassNSObjectB
PROP [ClassNSObjectB] label:[textB] value:[Some textB]
PROP [ClassNSObjectB] label:[numB] value:[1111]
PROP [ClassNSObjectB] label:[dateB] value:[2016-02-17 13:37:35 +0000]
PROP [ClassNSObjectB] label:[arrayB] value:[["B1", "B2"]]
classname:ClassNSObjectA
PROP [ClassNSObjectA] label:[textA] value:[Some textA]
PROP [ClassNSObjectA] label:[numA] value:[1111]
PROP [ClassNSObjectA] label:[dateA] value:[2016-02-17 13:37:35 +0000]
PROP [ClassNSObjectA] label:[arrayA] value:[["A1", "A2"]]
classname:NSObject
NSObject found - skipNSObjectRoot is true - SKIP this class - return empty dictionary
*****************************************************
*********** SCAN COMPLETE - DUMP DICT INFO***********
*****************************************************
dictOfIVars:
["numB": 1111, "numC": 1111, "arrayB": (
B1,
B2
), "dateA": 2016-02-17 13:37:35 +0000, "dateC": 2016-02-17 13:37:35 +0000, "dateB": 2016-02-17 13:37:35 +0000, "arrayC": (
C1,
C2
), "textC": Some textC, "arrayA": (
A1,
A2
), "textA": Some textA, "numA": 1111, "textB": Some textB]
KEYS:
arrayA
arrayB
arrayC
dateA
dateB
dateC
numA
numB
numC
textA
textB
textC
dictOfIVars.keys.count:12
=====================================================================================================================
========== TEST 2: recursively iterate up tree of NSObject subclasses - DO NOT include root object 'NSObject' in scan
=====================================================================================================================
classname:ClassNSObjectC
PROP [ClassNSObjectC] label:[textC] value:[Some textC]
PROP [ClassNSObjectC] label:[numC] value:[1111]
PROP [ClassNSObjectC] label:[dateC] value:[2016-02-17 13:37:35 +0000]
PROP [ClassNSObjectC] label:[arrayC] value:[["C1", "C2"]]
classname:ClassNSObjectB
PROP [ClassNSObjectB] label:[textB] value:[Some textB]
PROP [ClassNSObjectB] label:[numB] value:[1111]
PROP [ClassNSObjectB] label:[dateB] value:[2016-02-17 13:37:35 +0000]
PROP [ClassNSObjectB] label:[arrayB] value:[["B1", "B2"]]
classname:ClassNSObjectA
PROP [ClassNSObjectA] label:[textA] value:[Some textA]
PROP [ClassNSObjectA] label:[numA] value:[1111]
PROP [ClassNSObjectA] label:[dateA] value:[2016-02-17 13:37:35 +0000]
PROP [ClassNSObjectA] label:[arrayA] value:[["A1", "A2"]]
classname:NSObject
class has no superclassMirror
*****************************************************
*********** SCAN COMPLETE - DUMP DICT INFO***********
*****************************************************
dictOfIVars:
["numB": 1111, "numC": 1111, "arrayB": (
B1,
B2
), "dateA": 2016-02-17 13:37:35 +0000, "dateC": 2016-02-17 13:37:35 +0000, "dateB": 2016-02-17 13:37:35 +0000, "arrayC": (
C1,
C2
), "textC": Some textC, "arrayA": (
A1,
A2
), "textA": Some textA, "numA": 1111, "textB": Some textB]
KEYS:
arrayA
arrayB
arrayC
dateA
dateB
dateC
numA
numB
numC
textA
textB
textC
dictOfIVars.keys.count:12
======================================================================================================================
========== TEST 3: recursively iterate up tree of Swift subclasses
======================================================================================================================
classname:ClassCSwift
PROP [ClassCSwift] label:[textC] value:[C Swift]
PROP [ClassCSwift] label:[numC] value:[1111]
PROP [ClassCSwift] label:[dateC] value:[2016-02-17 13:37:35 +0000]
PROP [ClassCSwift] label:[arrayC] value:[["C1Swift", "C2Swift"]]
classname:ClassBSwift
PROP [ClassBSwift] label:[textB] value:[B Swift]
PROP [ClassBSwift] label:[numB] value:[1111]
PROP [ClassBSwift] label:[dateB] value:[2016-02-17 13:37:35 +0000]
PROP [ClassBSwift] label:[arrayB] value:[["B1Swift", "B2Swift"]]
classname:ClassASwift
PROP [ClassASwift] label:[textA] value:[A Swift]
PROP [ClassASwift] label:[numA] value:[1111]
PROP [ClassASwift] label:[dateA] value:[2016-02-17 13:37:35 +0000]
PROP [ClassASwift] label:[arrayA] value:[["A1Swift", "A2Swift"]]
class has no superclassMirror
*****************************************************
*********** SCAN COMPLETE - DUMP DICT INFO***********
*****************************************************
dictOfIVars:
["numB": 1111, "numC": 1111, "arrayB": (
B1Swift,
B2Swift
), "dateA": 2016-02-17 13:37:35 +0000, "dateC": 2016-02-17 13:37:35 +0000, "dateB": 2016-02-17 13:37:35 +0000, "arrayC": (
C1Swift,
C2Swift
), "textC": C Swift, "arrayA": (
A1Swift,
A2Swift
), "textA": A Swift, "numA": 1111, "textB": B Swift]
KEYS:
arrayA
arrayB
arrayC
dateA
dateB
dateC
numA
numB
numC
textA
textB
textC
dictOfIVars.keys.count:12
您可以简单地遍历所有 superclassMirror 获取属性。有多少层并不重要。
var mirror: Mirror? = Mirror(reflecting: child)
repeat {
for property in mirror!.children {
print("property: \(property)")
}
mirror = mirror?.superclassMirror()
} while mirror != nil
这是我的实现
- 支持继承链
- 支持嵌套对象
- 展开选项如果 .some
- 支持带有 rawValue 的枚举
- 支持数组
.
public protocol Serializable {
func serialize() -> [String: Any]
}
extension Serializable {
public func serialize() -> [String: Any] {
var result = [String: Any]()
var enumeratingMirror: Mirror? = Mirror(reflecting: self)
while true {
guard let mirror = enumeratingMirror else { break }
for child in mirror.children {
guard let label = child.label else { continue }
switch child.value {
case let serializable as Serializable:
if case .some(let value) = optional {
result[label] = value
}
case let rawRepresentable as RawRepresentable:
result[label] = rawRepresentable.getValueAsAny()
case let optional as Optional<Any>:
if case .some(let value) = optional {
result[label] = value
}
default:
result[label] = child.value
}
}
enumeratingMirror = mirror.superclassMirror
}
return result
}
}
extension Collection where Iterator.Element: Serializable {
public func serialize() -> [[String: Any]] {
return map { [=10=].serialize() }
}
}
extension RawRepresentable {
public func getValueAsAny() -> Any {
return rawValue
}
}
用法
class BaseUser: Serializable { let id: Int = 1 }
class User: BaseUser { let name: String = "Aryan" }
let user = User()
print(user.serialize()) // {"id": 1, "name": "Aryan"}
print([user].serialize()) // [{"id": 1, "name": "Aryan"}]
我的解决方案是使用
Mirror(self, children: properties, ancestorRepresentation: Mirror.AncestorRepresentation.generated)
而不是
Mirror(representing: self)
properties 是一个 DictionnaryLiteral 对象，包含我要镜像的属性。