ios - 符合 Swift NSObject 子类的 Objective-C 协议(protocol)的问题

Question

这段代码在 Swift 1.1 中运行得非常好

// Obj-C

@import Foundation;

@protocol HashableObject <NSObject>
- (NSUInteger)hash;
@end

// Swift

import Foundation

@objc class Object: NSObject, HashableObject {

    func hash() -> UInt {
        return 0
    }
}

然而，在最新的 Swift 1.2 和 XCode 6.3beta2 中，编译器提示 Method 'hash()' overrides Objective-C method 'hash' from superclass 'NSObject'

这是一个错误，还是其他什么从根本上改变了，代码是错误的？有什么解决方法吗？我的代码中有很多东西需要符合 Objective-C 库的某些协议(protocol)，这基本上破坏了一切，除了等待下一个 Swift 版本之外没有明显的解决方案。

Answer 1

NSObject 已经有 hash property :

protocol NSObjectProtocol {
    var hash: Int { get }

而且，Swift 1.2 会检测到这些错误的覆盖。来自发行说明:

Swift now detects discrepancies between overloading and overriding in the Swift type system and the effective behavior seen via the Objective-C runtime. (18391046, 18383574)

For example, the following conflict between the Objective-C setter for “property” in a class and the method “setProperty” in its extension is now diagnosed:

class A : NSObject {
  var property: String = "Hello" // note: Objective-C method 'setProperty:’
                                 // previously declared by setter for
                                 // 'property’ here
}
extension A {
    func setProperty(str: String) { } // error: method ‘setProperty’
                                      // redeclares Objective-C method
                                      //'setProperty:’
}