Question

我正在查看来自ScrollViewSuite的Apple示例代码。相比之下，我必须做错事。在他们的RootViewController中，他们执行：

- (void)loadView {
    [super loadView];

    // set the tag for the image view
    [imageView setTag:ZOOM_VIEW_TAG];

    // add gesture recognizers to the image view
    UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleSingleTap:)];
    UITapGestureRecognizer *doubleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleDoubleTap:)];
    UITapGestureRecognizer *twoFingerTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTwoFingerTap:)];

    [doubleTap setNumberOfTapsRequired:2];
    [twoFingerTap setNumberOfTouchesRequired:2];

    [imageView addGestureRecognizer:singleTap];
    [imageView addGestureRecognizer:doubleTap];
    [imageView addGestureRecognizer:twoFingerTap];

    [singleTap release];
    [doubleTap release];
    [twoFingerTap release];

    // calculate minimum scale to perfectly fit image width, and begin at that scale
    float minimumScale = [imageScrollView frame].size.width  / [imageView frame].size.width;
    [imageScrollView setMinimumZoomScale:minimumScale];
    [imageScrollView setZoomScale:minimumScale];
}

在IB中，他们将imageView作为imageScrollView的子视图。我的.xib设置方式相同。我将此代码放在viewDidLoad而不是loadView中。当我双击我的imageView时，我没有接到任何电话。我想知道为什么。以下是我们所做的版本：

- (void)viewDidLoad {
    [self updateOnScreenImages];  // this is where my imageView.image property gets set

    UITapGestureRecognizer *doubleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleDoubleTap:)];
    doubleTap.numberOfTapsRequired = 2;

    UITapGestureRecognizer *twoFingerTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTwoFingerTap:)];
    [doubleTap setNumberOfTouchesRequired:2];


    [self.imageView addGestureRecognizer:doubleTap];
    [self.imageView addGestureRecognizer:twoFingerTap];

    [doubleTap release];
    [twoFingerTap release];

}

与Apple正在做的事情相比，我做错了吗？逻辑似乎与我非常相似。但是当我双击时，我没有得到回调。我尝试将手势添加到self.scrollView中，但这也不起作用。思考？谢谢！

Answer 1

尝试添加：

   self.imageView.userInteractionEnabled = YES;

默认情况下UIImageView将该属性设置为NO
（苹果可能在XIB文件中对其进行了更改，您可能已经丢失了......）

Answer 2

#import "RootViewController.h"

#define ZOOM_VIEW_TAG 100
#define ZOOM_STEP 1.5


@interface RootViewController (UtilityMethods)
- (CGRect)zoomRectForScale:(float)scale withCenter:(CGPoint)center;
@end


@implementation RootViewController

@synthesize imageScrollView, imageView, mySlider;

- (IBAction) sliderValueChanged:(UISlider *)sender {
    mySlider.value = [NSString stringWithFormat:imageScrollView.[sender value]];

     //mySlider.value = [NSString stringWithFormat:@" %.1f", [sender value]];


    //myTextField.text = [NSString stringWithFormat:@" %.1f", [sender value]];
}


- (void)loadView {
    [super loadView];

    // set the tag for the image view
    [imageView setTag:ZOOM_VIEW_TAG];

    // add gesture recognizers to the image view
    UITapGestureRecognizer *singleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleSingleTap:)];
    UITapGestureRecognizer *doubleTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleDoubleTap:)];
    UITapGestureRecognizer *twoFingerTap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(handleTwoFingerTap:)];

    [doubleTap setNumberOfTapsRequired:2];
    [twoFingerTap setNumberOfTouchesRequired:2];

    [imageView addGestureRecognizer:singleTap];
    [imageView addGestureRecognizer:doubleTap];
    [imageView addGestureRecognizer:twoFingerTap];

    [singleTap release];
    [doubleTap release];
    [twoFingerTap release];

    // calculate minimum scale to perfectly fit image width, and begin at that scale
    float minimumScale = [imageScrollView frame].size.width  / [imageView frame].size.width;
    [imageScrollView setMinimumZoomScale:minimumScale];
    [imageScrollView setZoomScale:minimumScale];
}


- (void)viewDidUnload {
    self.imageScrollView = nil;
    self.imageView = nil;
}


- (void)dealloc {
    [imageScrollView release];
    [imageView release];
    [super dealloc];
}

#pragma mark UIScrollViewDelegate methods

- (UIView *)viewForZoomingInScrollView:(UIScrollView *)scrollView {
    return [imageScrollView viewWithTag:ZOOM_VIEW_TAG];
}

/************************************** NOTE **************************************/
/* The following delegate method works around a known bug in zoomToRect:animated: */
/* In the next release after 3.0 this workaround will no longer be necessary      */
/**********************************************************************************/
- (void)scrollViewDidEndZooming:(UIScrollView *)scrollView withView:(UIView *)view atScale:(float)scale {
    [scrollView setZoomScale:scale+0.01 animated:NO];
    [scrollView setZoomScale:scale animated:NO];
}

#pragma mark TapDetectingImageViewDelegate methods

- (void)handleSingleTap:(UIGestureRecognizer *)gestureRecognizer {
    // single tap does nothing for now
}

- (void)handleDoubleTap:(UIGestureRecognizer *)gestureRecognizer {
    // double tap zooms in
    float newScale = [imageScrollView zoomScale] * ZOOM_STEP;
    CGRect zoomRect = [self zoomRectForScale:newScale withCenter:[gestureRecognizer locationInView:gestureRecognizer.view]];
    [imageScrollView zoomToRect:zoomRect animated:YES];
}

- (void)handleTwoFingerTap:(UIGestureRecognizer *)gestureRecognizer {
    // two-finger tap zooms out
    float newScale = [imageScrollView zoomScale] / ZOOM_STEP;
    CGRect zoomRect = [self zoomRectForScale:newScale withCenter:[gestureRecognizer locationInView:gestureRecognizer.view]];
    [imageScrollView zoomToRect:zoomRect animated:YES];
}

#pragma mark Utility methods

- (CGRect)zoomRectForScale:(float)scale withCenter:(CGPoint)center {

    CGRect zoomRect;

    // the zoom rect is in the content view's coordinates. 
    //    At a zoom scale of 1.0, it would be the size of the imageScrollView's bounds.
    //    As the zoom scale decreases, so more content is visible, the size of the rect grows.
    zoomRect.size.height = [imageScrollView frame].size.height / scale;
    zoomRect.size.width  = [imageScrollView frame].size.width  / scale;

    // choose an origin so as to get the right center.
    zoomRect.origin.x    = center.x - (zoomRect.size.width  / 2.0);
    zoomRect.origin.y    = center.y - (zoomRect.size.height / 2.0);

    return zoomRect;
}

@end

双击可放大UIImageView

2 个答案: