swift - Swift：NSMutableSet -> 类型“CGPoint”不符合协议“AnyObject”

Question

为什么此代码会导致“类型 'CGPoint' 不符合协议 'AnyObject'”？

let mutableSet = NSMutableSet()
override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
    /* Called when a touch begins */
    touch = touches.anyObject() as UITouch!
    mutableSet.addObject(touch.locationInNode(self))
}

Answer 1

NSMutableSet只接受引用类型，但是CGPoint是一个结构，一个值类型。您可以将点包装在 anNSValue中以添加它。

mutableSet.addObject(NSValue(CGPoint: touch.locationInNode(self)))