存储并更新NSUserDefaults Xcode中的Swift Dictionary [英] Store and update a Swift Dictionary in NSUserDefaults Xcode

问题描述

当用户输入值时，我想存储和更新字典。一切似乎都运行到这段代码，应用程序崩溃：

I would like to store and update a Dictionary when a user enters a value. Everything seems to function until this code, and the application crashes:

override func viewDidLoad() {
    super.viewDidLoad()

    if NSUserDefaults.standardUserDefaults().objectForKey("dict") != nil  {
        answersSaved = NSUserDefaults.standardUserDefaults().objectForKey("dict") as [String:String]
    }
}

错误消息说anyObject不能转换为[String：String]。它提供添加！之后，然后应用程序崩溃。

The error message says "anyObject is not convertible to [String:String]. It offers to add ! after the as but then the app crashes.

dict是我的Dictionary变量，使用Strings作为值。

dict is my Dictionary variable with Strings as values.

我也有更新NSUserDefaults的代码，但似乎正常运行。

I also have code updating the NSUserDefaults but it appears to be functioning.

非常感谢！

推荐答案

猜测Xcode的版本低于6.3。

Guess your Xcode's version is below 6.3.

使用 dictionaryForKey：而不是 objectForKey：。字典不是Swift中的类类型是一个值类型。

Using dictionaryForKey: instead of objectForKey:.Dictionary is not a class type in Swift,it is a value type.

let userDefaults = NSUserDefaults.standardUserDefaults()

userDefaults.setValue(["key":"value"], forKey: "answersSaved") // fill data

if let answersSaved = userDefaults.dictionaryForKey("answersSaved") as? [String : String] {

    // [NSObject : AnyObject] can be converted to [String : String]

    if let value = answersSaved["key"] {

        println(value) // value
    }

}

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