方法load（）定义Objective-C类的方法'load'，这是不允许的Swift 1.2

Question

我正在使用Parse，并且我正在创建一个符合协议PFSubclassing的PFObject子类！ 这是工作一切正常，但现在，我使用雨燕1.2，这让我这个错误：

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

线1：方法“的load（）”定义的Objective-C类的方法“负荷”，这是不允许的斯威夫特1.2

任何人都有这个问题呢？我该如何解决？

Answer 1

有关于方法混写的NSHispster文章，在不同的环境对这个倒是：

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.

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

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更多信息形式开发论坛：

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.

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

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TL;博士initialize()和didFinishLaunchingWithOptions似乎是在斯威夫特这样的事情像样的地方。

Answer 2

我得到它的工作与替换它：

override class func initialize() { 
} 

Answer 3

我打电话Parse.setApplicationId之前在AppDelegate中registerSubclass()方法的PFObject每个子类中，它的作品。

Answer 4

覆盖load()从来没有与斯威夫特合作。更好的是它根本不叫。当时我为苹果公司提交了一个bug（Bug ID 18423731），最近我收到了一个回应，表示已经通过明确告知开发人员这个问题在Swift中不被允许解决。

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。即使文档另有说明。

Answer 5

试试这个：

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

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