捏手势在Xcode 8 swift 3中不起作用

Question

这是用于在捏合时更改背景颜色的代码。

import UIKit


class ViewController: UIViewController {

    @IBOutlet weak var mylabel: UILabel!
    let background = UIColor(red: 1.0, green: 0.98, blue: 0.96, alpha: 1.0)
    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = background
        let pinchGesture = UIPinchGestureRecognizer(target: self,  action:#selector(pinchAction(sender1:)))
        self.view.addGestureRecognizer(pinchGesture)

    }

    func pinchAction(sender1 sender:UIPinchGestureRecognizer){

        if sender.state == .began{
            mylabel.text = "Pinch Began"
            view.backgroundColor = UIColor.yellow
        }
        if sender.state == .changed{
            mylabel.text = String(format:"Pinch scale: %1.3f",sender.scale)
        }
        if sender.state == .ended{
            mylabel.text = "Pinch Ended"
            view.backgroundColor = background
        }
    }
}

我还在故事板中标记了“启用了用户交互”，但仍然没有发生任何事情。