Swift:包含 "complex" 数据的 pList
Swift: pList with "complex" data
在我阅读和尝试时:-) 我只能在 pList 文件上保存一些简单的数据类型。尽管如此,我还是喜欢使用结构、classes 等来表示我的数据。这应该尽可能容易地保存到 pList 文件并重新加载。
我明白了,NSData 是 pList 的有效类型。而且,这是一种通用数据类型。因此,将结构 move/convert/force 或 class 变量放入要保存和重新加载的 NSData 对象中是个好主意吗?怎么做到的?
直到现在我都在使用这样的东西来保存:
let dict: NSMutableDictionary = ["XYZ": "XYZ"]
// saving values
dict.setObject(myBasicArray, forKey: "BasicArray")
dict.writeToFile(path, atomically: false)
更新:
我使用了提供的代码并将其扩展为处理结构:
import Cocoa
struct SteeringItem {
var ext = String() // extension including dot e.g. ".JPG"
var bitmap = Int() // flag for grouping file types, e.g. photos
init?(ext: String, bitmap: Int) {
// Initialize stored properties.
self.ext = ext
self.bitmap = bitmap
}
}
class Foo {
let one: Int
let two: SteeringItem
init(one:Int, two: SteeringItem) {
self.one = one
self.two = two
}
init?(dict:[String: AnyObject]) {
guard let
one = dict["one"] as? Int,
two = dict["two"] as? SteeringItem else { return nil }
self.one = one
self.two = two
}
func toDictionary() -> [String: AnyObject] {
var retval = [String: AnyObject]()
if let
one = self.one as? AnyObject,
two = self.two as? AnyObject {
retval["one"] = one
retval["two"] = two
}
return retval
}
}
// create struct
let writeStruct = Foo(one: 1, two: SteeringItem(ext: "one",bitmap: 1)!)
print(writeStruct, "\n")
// write to plist
let writeDict = writeStruct.toDictionary() as NSDictionary
let path = ("~/test.plist" as NSString).stringByExpandingTildeInPath
writeDict.writeToFile(path, atomically: true)
// print contents of file
print(try NSString(contentsOfFile: path, encoding: NSUTF8StringEncoding))
// read plist and recreate struct
if let
readDict = NSDictionary(contentsOfFile: path) as? [String:AnyObject],
readStruct = Foo(dict: readDict) {
print(readStruct)
}
不过这个就不写了。使用 String 可以,使用 "struct SteeringItem" 则不行!
更新 2:class 而不是 struct
class SteeringItem : NSObject, NSCoding {
var ext = String() // extension including dot e.g. ".JPG"
var bitmap = Int() // flag for grouping file types, e.g. photos
func encodeWithCoder(aCoder: NSCoder) {
aCoder.encodeObject(ext, forKey: "ext")
aCoder.encodeObject(bitmap, forKey: "bitmap")
}
required convenience init?(coder aDecoder: NSCoder) {
let ext = aDecoder.decodeObjectForKey("ext") as! String
let bitmap = aDecoder.decodeObjectForKey("bitmap") as! Int
self.init(ext: ext, bitmap: bitmap)
}
init?(ext: String, bitmap: Int) {
// Initialize stored properties.
self.ext = ext
self.bitmap = bitmap
super.init()
}
}
有几种方法可以做到这一点,您可以遵守 NSCoding
协议,或者您可以编写方法将 class/struct 转换为字典并从那里进行序列化。
这是使用 NSCoding
protocol 的一个很好的介绍。
至于与字典相互转换,通常的方法是提供一个可失败的 init
方法,该方法采用 Dictionary<String, AnyObject>
来验证 key:value 对并将其复制到成员变量.您还提供了一种方法,该方法 returns a Dictionary<String, AnyObject>
具有与 init
相同的 key:value 对。然后,您可以通过调用 create 方法并序列化生成的 Dictionary
来进行序列化,您可以通过读入 Dictionary
并将其传递给 init
方法来进行反序列化。
这是一个转换示例:
/// Provides conversion to and from [String: AnyObject] for use in serialization
protocol Serializable {
init?(dict:[String: AnyObject])
func toDictionary() -> [String: AnyObject]
}
struct SteeringItem {
// Changed var to let, it's a good practice with a simple struct
let ext : String // extension including dot e.g. ".JPG"
let bitmap : Int // flag for grouping file types, e.g. photos
}
struct Foo {
let one: Int
let two: SteeringItem
}
// Add serialization to structs
extension SteeringItem: Serializable {
init?(dict:[String: AnyObject]) {
guard let
ext = dict["ext"] as? String,
bitmap = dict["bitmap"] as? Int else { return nil }
self.ext = ext
self.bitmap = bitmap
}
func toDictionary() -> [String: AnyObject] {
var retval = [String: AnyObject]()
if let
ext = self.ext as? AnyObject,
bitmap = self.bitmap as? AnyObject {
retval["ext"] = ext
retval["bitmap"] = bitmap
}
return retval
}
}
extension Foo: Serializable {
init?(dict:[String: AnyObject]) {
guard let
one = dict["one"] as? Int,
twoDict = dict["two"] as? [String: AnyObject],
two = SteeringItem(dict: twoDict) else { return nil }
self.one = one
self.two = two
}
func toDictionary() -> [String: AnyObject] {
var retval = [String: AnyObject]()
let twoDict = self.two.toDictionary()
if let
one = self.one as? AnyObject,
two = twoDict as? AnyObject {
retval["one"] = one
retval["two"] = two
}
return retval
}
}
以下是测试方法(在操场上):
import Foundation
// create struct
let writeStruct = Foo(one: 1, two: SteeringItem(ext: "jpg", bitmap: 1))
print(writeStruct, "\n")
// write to plist
let writeDict = writeStruct.toDictionary() as NSDictionary
let path = ("~/test.plist" as NSString).stringByExpandingTildeInPath
writeDict.writeToFile(path, atomically: true)
// print contents of file
print(try NSString(contentsOfFile: path, encoding: NSUTF8StringEncoding))
// read plist and recreate struct
if let
readDict = NSDictionary(contentsOfFile: path) as? [String:AnyObject],
readStruct = Foo(dict: readDict) {
print(readStruct)
}
结果:
Foo(one: 1, two: SteeringItem(ext: "jpg", bitmap: 1))
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>one</key>
<integer>1</integer>
<key>two</key>
<dict>
<key>bitmap</key>
<integer>1</integer>
<key>ext</key>
<string>jpg</string>
</dict>
</dict>
</plist>
Foo(one: 1, two: SteeringItem(ext: "jpg", bitmap: 1))
在我阅读和尝试时:-) 我只能在 pList 文件上保存一些简单的数据类型。尽管如此,我还是喜欢使用结构、classes 等来表示我的数据。这应该尽可能容易地保存到 pList 文件并重新加载。
我明白了,NSData 是 pList 的有效类型。而且,这是一种通用数据类型。因此,将结构 move/convert/force 或 class 变量放入要保存和重新加载的 NSData 对象中是个好主意吗?怎么做到的?
直到现在我都在使用这样的东西来保存:
let dict: NSMutableDictionary = ["XYZ": "XYZ"]
// saving values
dict.setObject(myBasicArray, forKey: "BasicArray")
dict.writeToFile(path, atomically: false)
更新: 我使用了提供的代码并将其扩展为处理结构:
import Cocoa
struct SteeringItem {
var ext = String() // extension including dot e.g. ".JPG"
var bitmap = Int() // flag for grouping file types, e.g. photos
init?(ext: String, bitmap: Int) {
// Initialize stored properties.
self.ext = ext
self.bitmap = bitmap
}
}
class Foo {
let one: Int
let two: SteeringItem
init(one:Int, two: SteeringItem) {
self.one = one
self.two = two
}
init?(dict:[String: AnyObject]) {
guard let
one = dict["one"] as? Int,
two = dict["two"] as? SteeringItem else { return nil }
self.one = one
self.two = two
}
func toDictionary() -> [String: AnyObject] {
var retval = [String: AnyObject]()
if let
one = self.one as? AnyObject,
two = self.two as? AnyObject {
retval["one"] = one
retval["two"] = two
}
return retval
}
}
// create struct
let writeStruct = Foo(one: 1, two: SteeringItem(ext: "one",bitmap: 1)!)
print(writeStruct, "\n")
// write to plist
let writeDict = writeStruct.toDictionary() as NSDictionary
let path = ("~/test.plist" as NSString).stringByExpandingTildeInPath
writeDict.writeToFile(path, atomically: true)
// print contents of file
print(try NSString(contentsOfFile: path, encoding: NSUTF8StringEncoding))
// read plist and recreate struct
if let
readDict = NSDictionary(contentsOfFile: path) as? [String:AnyObject],
readStruct = Foo(dict: readDict) {
print(readStruct)
}
不过这个就不写了。使用 String 可以,使用 "struct SteeringItem" 则不行!
更新 2:class 而不是 struct
class SteeringItem : NSObject, NSCoding {
var ext = String() // extension including dot e.g. ".JPG"
var bitmap = Int() // flag for grouping file types, e.g. photos
func encodeWithCoder(aCoder: NSCoder) {
aCoder.encodeObject(ext, forKey: "ext")
aCoder.encodeObject(bitmap, forKey: "bitmap")
}
required convenience init?(coder aDecoder: NSCoder) {
let ext = aDecoder.decodeObjectForKey("ext") as! String
let bitmap = aDecoder.decodeObjectForKey("bitmap") as! Int
self.init(ext: ext, bitmap: bitmap)
}
init?(ext: String, bitmap: Int) {
// Initialize stored properties.
self.ext = ext
self.bitmap = bitmap
super.init()
}
}
有几种方法可以做到这一点,您可以遵守 NSCoding
协议,或者您可以编写方法将 class/struct 转换为字典并从那里进行序列化。
这是使用 NSCoding
protocol 的一个很好的介绍。
至于与字典相互转换,通常的方法是提供一个可失败的 init
方法,该方法采用 Dictionary<String, AnyObject>
来验证 key:value 对并将其复制到成员变量.您还提供了一种方法,该方法 returns a Dictionary<String, AnyObject>
具有与 init
相同的 key:value 对。然后,您可以通过调用 create 方法并序列化生成的 Dictionary
来进行序列化,您可以通过读入 Dictionary
并将其传递给 init
方法来进行反序列化。
这是一个转换示例:
/// Provides conversion to and from [String: AnyObject] for use in serialization
protocol Serializable {
init?(dict:[String: AnyObject])
func toDictionary() -> [String: AnyObject]
}
struct SteeringItem {
// Changed var to let, it's a good practice with a simple struct
let ext : String // extension including dot e.g. ".JPG"
let bitmap : Int // flag for grouping file types, e.g. photos
}
struct Foo {
let one: Int
let two: SteeringItem
}
// Add serialization to structs
extension SteeringItem: Serializable {
init?(dict:[String: AnyObject]) {
guard let
ext = dict["ext"] as? String,
bitmap = dict["bitmap"] as? Int else { return nil }
self.ext = ext
self.bitmap = bitmap
}
func toDictionary() -> [String: AnyObject] {
var retval = [String: AnyObject]()
if let
ext = self.ext as? AnyObject,
bitmap = self.bitmap as? AnyObject {
retval["ext"] = ext
retval["bitmap"] = bitmap
}
return retval
}
}
extension Foo: Serializable {
init?(dict:[String: AnyObject]) {
guard let
one = dict["one"] as? Int,
twoDict = dict["two"] as? [String: AnyObject],
two = SteeringItem(dict: twoDict) else { return nil }
self.one = one
self.two = two
}
func toDictionary() -> [String: AnyObject] {
var retval = [String: AnyObject]()
let twoDict = self.two.toDictionary()
if let
one = self.one as? AnyObject,
two = twoDict as? AnyObject {
retval["one"] = one
retval["two"] = two
}
return retval
}
}
以下是测试方法(在操场上):
import Foundation
// create struct
let writeStruct = Foo(one: 1, two: SteeringItem(ext: "jpg", bitmap: 1))
print(writeStruct, "\n")
// write to plist
let writeDict = writeStruct.toDictionary() as NSDictionary
let path = ("~/test.plist" as NSString).stringByExpandingTildeInPath
writeDict.writeToFile(path, atomically: true)
// print contents of file
print(try NSString(contentsOfFile: path, encoding: NSUTF8StringEncoding))
// read plist and recreate struct
if let
readDict = NSDictionary(contentsOfFile: path) as? [String:AnyObject],
readStruct = Foo(dict: readDict) {
print(readStruct)
}
结果:
Foo(one: 1, two: SteeringItem(ext: "jpg", bitmap: 1))
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>one</key>
<integer>1</integer>
<key>two</key>
<dict>
<key>bitmap</key>
<integer>1</integer>
<key>ext</key>
<string>jpg</string>
</dict>
</dict>
</plist>
Foo(one: 1, two: SteeringItem(ext: "jpg", bitmap: 1))