使用选择器'touchesBegan：withEvent：'的覆盖方法具有不兼容的类型'（NSSet，UIEvent） - > （）” [英] Overriding method with selector 'touchesBegan:withEvent:' has incompatible type '(NSSet, UIEvent) -> ()'

问题描述

Xcode 6.3。在实现UITextFieldDelegate协议的类中，我想重写touchesBegan（）方法以隐藏键盘。如果我在函数规范中避免了编译器错误，那么尝试从Set或NSSet中读取touch时会出现编译器错误，否则super.touchesBegan（touches，withEvent：event）会抛出错误。在Xcode 6.2中编译的这些组合之一！ （那么SwiftSet的文档在哪里以及如何从一个元素中获取元素？）

Xcode 6.3. Within a class implementing UITextFieldDelegate protocol, I would like to override touchesBegan() method to possibly hide the keyboard. If I avoid a compiler error in the function spec, then there is a complier error trying to read the "touch" from the Set or NSSet, or else the super.touchesBegan(touches , withEvent:event) throws an error. One of these combinations compiled in Xcode 6.2! (So where is documentation to Swift "Set" and how to get an element from one?)

 override func touchesBegan(touches: NSSet, withEvent event: UIEvent) { 
    // Hiding the Keyboard when the User Taps the Background
        if let touch =  touches.anyObject() as? UITouch {
            if nameTF.isFirstResponder() && touch.view != nameTF {
                nameTF.resignFirstResponder();
            }
        }
        super.touchesBegan(touches , withEvent:event)
    }

尝试：

override func touchesBegan(touches: NSSet, withEvent event: UIEvent) or
override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent) 

编译器错误：
使用选择器'touchesBegan：withEvent：'的覆盖方法具有不兼容的类型'（NSSet，UIEvent） - >（）'
和

Compiler error: Overriding method with selector 'touchesBegan:withEvent:' has incompatible type '(NSSet, UIEvent) -> ()' and

super.touchesBegan(touches , withEvent:event)

还抱怨

'NSSet'不能隐式转换为'Set';你的意思是使用'as'来明确转换吗？

'NSSet' is not implicitly convertible to 'Set'; did you mean to use 'as' to explicitly convert?

尝试：

override func touchesBegan(touches: Set<AnyObject>, withEvent event: UIEvent) 

编译器错误：
类型'AnyObject'不符合协议'Hashable'

Compiler error: Type 'AnyObject' does not conform to protocol 'Hashable'

尝试：

override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) 

编译错误

if let touch = touches.anyObject() as? UITouch 

'Set'没有名为'anyObject'的成员但是函数规范和调用super （）没问题！

'Set' does not have a member named 'anyObject' BUT the function spec and call to super() are OK!

尝试：

override func touchesBegan(touches: NSSet<AnyObject>, withEvent event: UIEvent) -> () or
override func touchesBegan(touches: NSSet<NSObject>, withEvent event: UIEvent) 

编译器错误：
无法专门化非泛型类型'NSSet'

Compiler error: Cannot specialize non-generic type 'NSSet'

推荐答案

Swift 1.2（Xcode 6.3）引入了一个本地 Set 类型，它将
与 NSSet 连接起来。这在 Swift博客和
Xcode 6.3发行说明，但是显然尚未添加到官方文档中（更新：正如 Ahmad Ghadiri所指出的那样，它是现在记录）。

Swift 1.2 (Xcode 6.3) introduced a native Set type that bridges with NSSet. This is mentioned in the Swift blog and in the Xcode 6.3 release notes, but apparently not yet added to the official documentation (update: As Ahmad Ghadiri noted, it is documented now).

现在将 UIResponder 方法声明为

func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent)

你可以这样覆盖它：

override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) {
    if let touch = touches.first as? UITouch {
        // ...
    }
    super.touchesBegan(touches , withEvent:event)
}

Swift 2更新（Xcode 7）：（比较覆盖Swift 2中的func错误）

override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
    if let touch = touches.first {
        // ...
    }
    super.touchesBegan(touches, withEvent:event)
}

Swift 3的更新：

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    if let touch = touches.first {
        // ...
    }
    super.touchesBegan(touches, with: event)
}

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