ScrollView 下的iOS swift 4 imageview : double tap to zoom out

Question

我已经应用 ImageView 通过捏合来放大/缩小。那很容易。在 ImageView 上应用双击时，无法检测到选择方法。

我使用 Xcode 9 和 swift 4 。你能告诉我 ScrollView 是否应该应用双击手势吗？

 var previewImage : UIImage? = nil


    override func viewDidLoad() {
        super.viewDidLoad()

        scrollView.minimumZoomScale = 1.0
        scrollView.maximumZoomScale = 6.0
        imageView.image = previewImage

        let doubleTap =  UITapGestureRecognizer.init(target: self, action: #selector(self.sampleTapGestureTapped(recognizer:)))
        doubleTap.numberOfTapsRequired = 2
        imageView.addGestureRecognizer(doubleTap)
        // Do any additional setu p after loading the view.
    } 

    @objc func sampleTapGestureTapped(recognizer: UITapGestureRecognizer) {
        print("Tapping working")
    }


}

extension PhotoReviewController: UIScrollViewDelegate {

    func viewForZooming(in scrollView: UIScrollView) -> UIView? {

        return imageView
    }
}

Answer 1

来自docs UIImageView 的属性 isUserInteractionEnabled。

This class changes the default value of this property to false.

因此，如果您只启用用户交互，您的问题应该得到解决。

imageView.isUserInteractionEnabled = true

如果还是不行。检查是否有其他 View 阻止了此 View 的触摸。