ios - 如何在 iOS 中点击缩放和双击缩小？

Question

我正在开发一个应用程序以使用 UIScrollView 显示 UIImages 的画廊，我的问题是，如何点击以缩放并双击以缩小，在使用UIScrollView 处理时它是如何工作的。

Answer 1

您需要实现 UITapGestureRecognizer - 文档 here - 在你的 View Controller 中

- (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:

- (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];
}

希望对你有帮助