如何在iOS中轻按以放大和双击以缩小？

Question

我正在开发一个应用程序，UIImages通过使用来显示的画廊UIScrollView，我的问题是，如何点按zoom并双击以zoom退出，使用处理时它是如何工作的UIScrollView。

Answer 1

您需要实现UITapGestureRecognizer -文档在这里 -在你的viewController- (void)viewDidLoad{    [super viewDidLoad];           // what object is going to handle the gesture when it gets recognised ?    // the argument for tap is the gesture that caused this message to be sent    UITapGestureRecognizer *tapOnce = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapOnce:)];    UITapGestureRecognizer *tapTwice = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapTwice:)];    // set number of taps required    tapOnce.numberOfTapsRequired = 1;    tapTwice.numberOfTapsRequired = 2;    // stops tapOnce from overriding tapTwice    [tapOnce requireGestureRecognizerToFail:tapTwice];    // now add the gesture recogniser to a view     // this will be the view that recognises the gesture      [self.view addGestureRecognizer:tapOnce];    [self.view addGestureRecognizer:tapTwice];}基本上，这段代码是说，UITapGesture在self.view方法中注册a时，将调用tapOnce或tapTwice，self具体取决于它是单击还是双击。因此，您需要将以下tap方法添加到您的UIViewController：- (void)tapOnce:(UIGestureRecognizer *)gesture{    //on a single  tap, call zoomToRect in UIScrollView    [self.myScrollView zoomToRect:rectToZoomInTo animated:NO];}- (void)tapTwice:(UIGestureRecognizer *)gesture{    //on a double tap, call zoomToRect in UIScrollView    [self.myScrollView zoomToRect:rectToZoomOutTo animated:NO];}希望能有所帮助

Answer 2

Swift 3.0版本，双击可放大两次。@IBOutlet weak var scrollView: UIScrollView!@IBOutlet weak var imageView: UIImageView!某个地方（通常在viewDidLoad中）：let tapRecognizer = UITapGestureRecognizer(target: self, action: #selector(onDoubleTap(gestureRecognizer:)))tapRecognizer.numberOfTapsRequired = 2scrollView.addGestureRecognizer(tapRecognizer)处理程序：func onDoubleTap(gestureRecognizer: UITapGestureRecognizer) {    let scale = min(scrollView.zoomScale * 2, scrollView.maximumZoomScale)    if scale != scrollView.zoomScale {        let point = gestureRecognizer.location(in: imageView)        let scrollSize = scrollView.frame.size        let size = CGSize(width: scrollSize.width / scale,                          height: scrollSize.height / scale)        let origin = CGPoint(x: point.x - size.width / 2,                             y: point.y - size.height / 2)        scrollView.zoom(to:CGRect(origin: origin, size: size), animated: true)        print(CGRect(origin: origin, size: size))    }}