方法 load() 定义了 Objective-C 类方法“load"，这是 Swift 1.2 不允许的 [英] Method load() defines Objective-C class method 'load', which is not permitted by Swift 1.2
问题描述
我正在使用 Parse 并且我正在创建一个符合 PFSubclassing 协议的 PFObject 子类！一切正常，但现在我使用的是 Swift 1.2，它给了我这个错误:
I'm using Parse and I'm creating a PFObject subclass conforming to the protocol PFSubclassing! It was working all fine, but now I'm using Swift 1.2 and it gives me this error:
1. override class func load() {
2. self.registerSubclass()
3. }
第 1 行:方法 'load()' 定义了 Objective-C 类方法 'load'，这是 Swift 1.2 不允许的
On line 1: Method 'load()' defines Objective-C class method 'load', which is not permitted by Swift 1.2
有人遇到过这个问题吗?我该如何解决?
Anyone have this problem yet? How can I fix?
推荐答案
NSHispster 有一篇关于 method swizzling 的文章，在不同的上下文中涉及到这个:
There is an NSHispster article about method swizzling that touches on this in different context:
不幸的是，在 Swift 中实现的加载类方法从来没有由运行时调用，使该推荐变得不可能.相反，我们只能在第二个选项中进行选择:
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:
在 initialize 中实现方法 swizzling. 这可以安全地完成，只要您在执行时检查类型并将 swizzling 包装在dispatch_once(无论如何你都应该这样做).
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).
在应用程序委托中实现方法 swizzling. 无需通过类扩展添加方法 swizzling，只需向应用程序添加方法委托时执行application(_:didFinishLaunchingWithOptions:) 被调用.根据您正在修改的类，这可能就足够了，应该保证你的代码每次都被执行.
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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来自开发论坛的更多信息:
More info form dev forums:
Swift 1.1 允许您使用class func"定义+load"方法load()"，但它们实际上并未在您的应用程序启动时运行就像 Objective-C +load 方法一样.Swift 1.2 禁止它们以避免这可能会奏效.
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;dr initialize() 和 didFinishLaunchingWithOptions 在 Swift 中似乎是处理此类事情的好地方.
tl;dr initialize() and didFinishLaunchingWithOptions seem to be decent places for such things in Swift.
这篇关于方法 load() 定义了 Objective-C 类方法“load"，这是 Swift 1.2 不允许的的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
