按住按钮“重复射击”

我已经提到了无数关于按住按钮的其他问题，但与 Swift 相关的问题并不多。我有一个使用 touchUpInside 事件连接到按钮的函数：

@IBAction func singleFire(sender: AnyObject){
    //code
}

...还有另一个函数，该函数旨在在按住同一按钮时重复调用上述函数，并在不再按下该按钮时停止：

@IBAction func speedFire(sender: AnyObject){

    button.addTarget(self, action: "buttonDown:", forControlEvents: .TouchDown)
    button.addTarget(self, action: "buttonUp:", forControlEvents: .TouchUpOutside)

    func buttonDown(sender: AnyObject){
        timer = NSTimer.scheduledTimerWithTimeInterval(0.3, target: self, selector: "singleFire", userInfo: nil, repeats: true)     
    }

    func buttonUp(sender: AnyObject){
        timer.invalidate()
    }
}

我不确定我做错了什么，并且我不知道如何为不同的功能设置同一个按钮的触摸事件。

当您按住按钮时，您希望快速重复射击。

Your buttonDown and buttonUp方法需要在顶层定义，而不是在另一个函数内部定义。出于演示目的，放弃接线会更清楚@IBActions 从故事板，只需设置按钮viewDidLoad:

class ViewController: UIViewController {

    @IBOutlet weak var button: UIButton!
    var timer: Timer?
    var speedAmmo = 20

    @objc func buttonDown(_ sender: UIButton) {
        singleFire()
        timer = Timer.scheduledTimer(timeInterval: 0.3, target: self, selector: #selector(rapidFire), userInfo: nil, repeats: true)
    }

    @objc func buttonUp(_ sender: UIButton) {
        timer?.invalidate()
    }

    func singleFire() {
        print("bang!")
    }

    @objc func rapidFire() {
        if speedAmmo > 0 {
            speedAmmo -= 1
            print("bang!")
        } else {
            print("out of speed ammo, dude!")
            timer?.invalidate()
        }
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        // These could be added in the Storyboard instead if you mark
        // buttonDown and buttonUp with @IBAction
        button.addTarget(self, action: #selector(buttonDown), for: .touchDown)
        button.addTarget(self, action: #selector(buttonUp), for: [.touchUpInside, .touchUpOutside])
    }
}

另外，我也改变了.touchUpOutside to [.touchUpInside, .touchUpOutside]（捕获两个触摸事件）并调用singleFire在最初的buttonDown用于单火。通过这些更改，按下按钮会立即触发，然后触发每个0.3只要按住按钮，就会持续几秒钟。

The button can be wired up in the Storyboard instead of setting it up in viewDidLoad. In this case, add @IBAction to buttonDown and buttonUp. Then Control-click on your button in the Storyboard and drag from the circle next to Touch Down to func buttonDown, and drag from the circles next to Touch Up Inside and Touch Up Outside to func buttonUp.