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 = 2

scrollView.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))

    }

}