双击以放大UIImageView

Question

我正在查看ScrollViewSuite中的苹果示例代码。相比之下，我一定做错了什么。在他们的RootViewController中，他们这样做：

- (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，它们将其imageView作为imageScrollView的子视图。我的.xib也是以同样的方式设置的。我把这段代码放在我的viewDidLoad中，而不是loadView中。双击我的imageView时不会接到任何电话。我想知道为什么。这是我对他们所做的事情的描述：

- (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];
}

与苹果相比，我做错了什么吗？逻辑似乎和我很相似。但当我双击时，我不会得到回拨。我也试着在self.scrollView中添加手势，但也不起作用。想法？谢谢

Answer 1

尝试添加：

self.imageView.userInteractionEnabled = YES;

默认情况下，UIImageView的属性设置为NO
(苹果可能在XIB文件中更改了它，您可能已经丢失了它…)

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