ios - 双击无法缩放图像

Question

我按如下方式加载 ImageView 。 self.displayReceivedImageScrollView 是在头文件中定义的 ScrollView 属性。

   _displayImage.image = nil;


        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^(void) {
            NSData *data0 = [NSData dataWithContentsOfURL: [NSURL URLWithString:savedValue]];
            UIImage *image = [UIImage imageWithData: data0];

            dispatch_sync(dispatch_get_main_queue(), ^(void) {
                _displayImage.image = image;
            });
        });


    UITapGestureRecognizer *doubleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleDoubleTap:)];

    [doubleTap setNumberOfTapsRequired:2];

    [self.displayReceivedImageScrollView addGestureRecognizer:doubleTap];

以下是我的 doubleTap 处理程序。我希望在用户双击图像时缩放图像。

- (void)handleDoubleTap:(UIGestureRecognizer *)gestureRecognizer {

    if(self.displayReceivedImageScrollView.zoomScale > self.displayReceivedImageScrollView.minimumZoomScale)
        [self.displayReceivedImageScrollView setZoomScale:self.displayReceivedImageScrollView.minimumZoomScale animated:YES];
    else
        [self.displayReceivedImageScrollView setZoomScale:self.displayReceivedImageScrollView.maximumZoomScale animated:YES];

}

但问题是，图像没有被缩放。 handleDoubleTap 方法根本没有被触发，为什么会这样？

Answer 1

您可以通过将 View 放入 ScrollView 和配置来启用缩放:

@property(nonatomic) CGFloat minimumZoomScale;     // default is 1.0
@property(nonatomic) CGFloat maximumZoomScale;     // default is 1.0. must be > minimum zoom scale to enable zooming