方法load（）定義Objective-C類的方法'load'，這是不允許的Swift 1.2

Question

我正在使用Parse，並且我正在創建一個符合協議PFSubclassing的PFObject子類！ 這是工作一切正常，但現在，我使用雨燕1.2，這讓我這個錯誤：

1. override class func load() { 
2.  self.registerSubclass() 
3. } 

線1：方法「的load（）」定義的Objective-C類的方法「負荷」，這是不允許的斯威夫特1.2

任何人都有這個問題呢？我該如何解決？

Answer 1

有關於方法混寫的NSHispster文章，在不同的環境對這個倒是：

Unfortunately, a load class method implemented in Swift is never called by the runtime, rendering that recommendation an impossibility. Instead, we're left to pick among second-choice options:

• Implement method swizzling in initialize. This can be done safely, so long as you check the type at execution time and wrap the swizzling in dispatch_once (which you should be doing anyway).

• Implement method swizzling in the app delegate. Instead of adding method swizzling via a class extension, simply add a method to the app delegate to be executed when application(_:didFinishLaunchingWithOptions:) is called. Depending on the classes you're modifying, this may be sufficient and should guarantee your code is executed every time.

鏈接：http://nshipster.com/swift-objc-runtime/

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更多信息形式開發論壇：

Swift 1.1 allowed you to define "+load" methods with "class func load()", but they were not actually run at startup time of your app like Objective-C +load methods are. Swift 1.2 bans them to avoid the impression that this might work.

鏈接：https://devforums.apple.com/message/1102025#1102025

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TL;博士initialize()和didFinishLaunchingWithOptions似乎是在斯威夫特這樣的事情像樣的地方。

Answer 2

我得到它的工作與替換它：

override class func initialize() { 
} 

Answer 3

我打電話Parse.setApplicationId之前在AppDelegate中registerSubclass()方法的PFObject每個子類中，它的作品。

Answer 4

覆蓋load()從來沒有與斯威夫特合作。更好的是它根本不叫。當時我爲蘋果公司提交了一個bug（Bug ID 18423731），最近我收到了一個迴應，表示已經通過明確告知開發人員這個問題在Swift中不被允許解決。

extension UIButton { 
    // !! never called 
    override public class func load() { // Method 'load()' defines Objective-C class method 'load', which is not permitted by Swift 1.2 
     super.load() 
     println("not called earlier anyway"); 
    } 
} 

所以....不要。即使文檔另有說明。

Answer 5

試試這個：

override class func initialize() { 
    var onceToken : dispatch_once_t = 0; 
    dispatch_once(&onceToken) { 
     self.registerSubclass() 
    } 
} 

解析文檔已更新：https://www.parse.com/docs/ios/guide#objects-subclassing-pfobject