问题描述

我正在开发一个应用程序以使用 UIScrollView 显示 UIImages 库，我的问题是，如何点击到 zoom并双击以 zoom 缩小，使用 UIScrollView 处理时它是如何工作的.

I'm developing an application to display a gallery of UIImages by using a UIScrollView, my question is, how to tap to zoom and double tap to zoom out, how does it work when handling with UIScrollView.

推荐答案

你需要实现 UITapGestureRecognizer - docs 这里 - 在你的视图控制器中

You need to implement UITapGestureRecognizer - docs here - in your 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，当 UITapGesture 在 self.view 中注册时，方法 tapOnce 或 tapTwice 将在 self 中调用，具体取决于它是单击还是双击.因此，您需要将这些点击方法添加到您的 UIViewController:

Basically this code is saying that when a UITapGesture is registered in self.view the method tapOnce or tapTwice will be called in self depending on if its a single or double tap. You therefore need to add these tap methods to your 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];
}

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