Ios Select 器touchesBegan：withEvent：的覆盖方法具有不兼容的类型(NSSet，UIEvent)>()

Xcode 6.3.在实现UITextFieldDelegate协议的类中，我想重写touch chesBegan()方法以可能隐藏键盘.如果我在函数规范中避免了编译器错误，那么try 从Set或NSSet读取"touch"时会出现编译器错误，否则super.touch chesBegan(touch，with Event:event)会抛出错误.这些组合之一是用Xcode6.2编译的！(那么，SWIFT的文档在哪里"设置"，以及如何从其中获取元素？)

 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)
    }

try :

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

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

super.touchesBegan(touches , withEvent:event)

也在抱怨

"NSSet"不能隐式转换为"Set"；是否要使用"As"显式转换？

try :

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

编译器错误: 类型"AnyObject"不符合协议"Hasable"

try :

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

编译器错误在

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

"set"没有名为"anyObject"的成员，但是函数规范和对Super()的调用都是正常的！

try :

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""