将对象添加到枚举给我错误

Question

我有一个enum和一个指向enum中某个对象的变量。

enum Collection {
    case First, Second, Third, Fourth
}
var myCollection = Collection.Second

我想将 myCollection 传递给 NSUserDefaults。这是我所做的：（我希望 viewDidLoad 是放置它的正确位置。）

override func viewDidLoad() {
    super.viewDidLoad()

    // Save the sort by NSUserDefualt
    let defaults = NSUserDefaults.standardUserDefaults()
    defaults.setObject(self.myCollection, forKey: "myKey")
}

在最后一行，我收到以下错误：

Cannot invoke 'setObject' with an argument list of type '(myViewController.Collection, forKey: String)'

我做错了什么，我该如何解决？

更新

这有意义吗？

let defaults = NSUserDefaults.standardUserDefaults()
let defaultRawValue = defaults.integerForKey("myKey")
if defaultRawValue != nil {
    defaults.setInteger(myCollection.rawValue, forKey: "myKey")
} else {
    defaults.setInteger(1, forKey: "myKey")
}
myCollection = Collection(rawValue: defaultRawValue)!

Answer 1

NSUserDefaults 只能取 PropertyList：https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/PropertyLists/AboutPropertyLists/AboutPropertyLists.html

尝试

enum Collection:Int{
        case First=1, Second, Third, Fourth
}
var myCollection = Collection.Second

override func viewDidLoad() {
        super.viewDidLoad()

        let defaults = NSUserDefaults.standardUserDefaults()
        let defaultRawValue = defaults.integerForKey("myKey")
        if defaultRawValue > 0{
            myCollection = Collection(rawValue: defaultRawValue)!
        }
        else
        {
            defaults.setInteger(1, forKey: "myKey")
            myCollection = Collection(rawValue: 1)
        }
}

Answer 2

The NSUserDefaults class provides convenience methods for accessing common types such as floats, doubles, integers, Booleans, and URLs. A default object must be a property list, that is, an instance of (or for collections a combination of instances of): NSData, NSString, NSNumber, NSDate, NSArray, or NSDictionary.

因此，如果您想将枚举存储在 NSUserDefaults 中，请使用 rawValue 作为您的枚举。这里我使用String，像这样：

enum Collection: String {
    case First = "First"
    case Second = "Second"
    case Third = "Third"
    case Fourth = "Fourth"
}
//create myCollection
var myCollection = Collection(rawValue: "Second")

并存储它：

override func viewDidLoad() {
super.viewDidLoad()

// Save the sort by NSUserDefualt
let defaults = NSUserDefaults.standardUserDefaults()
defaults.setObject(self.myCollection.rawValue, forKey: "myKey")
}

将对象添加到枚举给我错误

Adding object to enum gives me error

enums

nsuserdefaults

ios

swift