UISwipeGestureRecognizer调用了两次 [英] UISwipeGestureRecognizer called twice
本文介绍了UISwipeGestureRecognizer调用了两次的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我正在实现我正在实施的视图的问题。
I'm having problems with a view I'm implementing.
这是一个在CATiledLayer中显示pdf页面的视图。该平铺视图位于UISCrollView内。
It's a view that shows a pdf page in a CATiledLayer. That tiled view is inside an UISCrollView.
我将视图控制为ZoomingPDFView苹果示例。我做了一些修改，以便在未启用滚动时识别滑动手势，并在此站点上提供各种线程和问题的建议。那时手势被称为一次。但是当我需要分离视图并委托滑动以缓存页面并执行多功能视图时，我创建了一个视图控制器来处理滑动手势，页面加载方法提高了pdf视图的性能。
I had the view controlling itself as the "ZoomingPDFView" apple example. I made a few modifications so it would recognize swiping gestures when scrolling is not enabled and advice in various threads and questions on this site. At that time the gestures were called once. But as I needed to decouple the view and delegate the swiping to cache the pages and do a versatile view, I created a view controller to handle the swiping gestures and the page loading methods increase the performance of the pdf view.
既然我一边有视图，另一边有控制器，两次检测到滑动手势，我甚至无法解决问题。
Now that I have the view on one side and the controller on the other side, swiping gestures are detected twice and I can't get even a clue of the issue.
这是控制台输出
2010-11-19 11:45:08.370 ZoomingPDFViewerForIPad[20327:207] initWithFrame and page
2010-11-19 11:45:08.530 ZoomingPDFViewerForIPad[20327:207] drawPage
2010-11-19 11:45:08.531 ZoomingPDFViewerForIPad[20327:207] scale: 1.000000
2010-11-19 11:45:08.531 ZoomingPDFViewerForIPad[20327:207] pdf scale: 1.290062
2010-11-19 11:45:08.532 ZoomingPDFViewerForIPad[20327:207] pdf initial scale: 1.290062
2010-11-19 11:45:15.488 ZoomingPDFViewerForIPad[20327:207] left
2010-11-19 11:45:15.489 ZoomingPDFViewerForIPad[20327:207] left
2010-11-19 11:45:15.490 ZoomingPDFViewerForIPad[20327:207] initWithFrame and page
2010-11-19 11:45:15.538 ZoomingPDFViewerForIPad[20327:207] drawPage
2010-11-19 11:45:15.538 ZoomingPDFViewerForIPad[20327:207] scale: 1.000000
2010-11-19 11:45:15.539 ZoomingPDFViewerForIPad[20327:207] pdf scale: 1.290062
2010-11-19 11:45:15.539 ZoomingPDFViewerForIPad[20327:207] pdf initial scale: 1.290062
2010-11-19 11:45:15.540 ZoomingPDFViewerForIPad[20327:1a07] initWithFrame and page
2010-11-19 11:45:15.541 ZoomingPDFViewerForIPad[20327:5f07] initWithFrame and page
2010-11-19 11:45:15.593 ZoomingPDFViewerForIPad[20327:1a07] drawPage
2010-11-19 11:45:15.594 ZoomingPDFViewerForIPad[20327:1a07] scale: 1.000000
2010-11-19 11:45:15.594 ZoomingPDFViewerForIPad[20327:1a07] pdf scale: 1.290062
2010-11-19 11:45:15.595 ZoomingPDFViewerForIPad[20327:1a07] pdf initial scale: 1.290062
2010-11-19 11:45:15.695 ZoomingPDFViewerForIPad[20327:5f07] drawPage
2010-11-19 11:45:15.704 ZoomingPDFViewerForIPad[20327:5f07] scale: 1.000000
2010-11-19 11:45:15.707 ZoomingPDFViewerForIPad[20327:5f07] pdf scale: 1.290062
2010-11-19 11:45:15.713 ZoomingPDFViewerForIPad[20327:5f07] pdf initial scale: 1.290062
这里是代码：
#import <UIKit/UIKit.h>
@class TiledPDFView;
@protocol PDFScrollViewDelegate;
@interface PDFScrollView : UIScrollView <UIScrollViewDelegate> {
// The TiledPDFView that is currently front most
TiledPDFView *pdfView;
// The old TiledPDFView that we draw on top of when the zooming stops
TiledPDFView *oldPDFView;
// A low res image of the PDF page that is displayed until the TiledPDFView
// renders its content.
UIImageView *backgroundImageView;
id<PDFScrollViewDelegate,NSObject> pdfViewDelegate;
// current pdf zoom scale
CGFloat pdfScale;
CGPDFPageRef page;
CGPDFDocumentRef pdf;
CGFloat initialScale;
TiledPDFView *initialTiledView;
int currentPage;
int pageCount;
UITapGestureRecognizer *doubleTap,*twoFingerDoubleTap;
UISwipeGestureRecognizer *rightSwipe, *leftSwipe;
}
@property (nonatomic,retain) id<PDFScrollViewDelegate> pdfViewDelegate;
-(id)initWithFrame:(CGRect)rect;
-(id)initWithFrame:(CGRect)frame andPDFPage:(CGPDFPageRef)aPage;
-(void)enableGestures;
-(void)drawPage;
@end
@implementation PDFScrollView
@synthesize pdfViewDelegate;
….
-(void)enableGestures{
leftSwipe = [[UISwipeGestureRecognizer alloc ]initWithTarget:self action:@selector(handleRightSwipe:)];
leftSwipe.direction = UISwipeGestureRecognizerDirectionRight;
[self addGestureRecognizer:leftSwipe];
//add right swipe
rightSwipe = [[UISwipeGestureRecognizer alloc ]initWithTarget:self action:@selector(handleLeftSwipe:)];
rightSwipe.direction = UISwipeGestureRecognizerDirectionLeft;
[self addGestureRecognizer:rightSwipe];
doubleTap = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(handleDoubleTap:)];
doubleTap.numberOfTapsRequired =2;
doubleTap.numberOfTouchesRequired =1;
[self addGestureRecognizer:doubleTap];
twoFingerDoubleTap = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(handleTwoFingerDoubleTap:)];
twoFingerDoubleTap.numberOfTapsRequired =2;
twoFingerDoubleTap.numberOfTouchesRequired =2;
[self addGestureRecognizer:twoFingerDoubleTap];
}
// some more code
@end
#import <UIKit/UIKit.h>
#import "PDFScrollViewDelegate.h"
@class TiledPDFView;
@interface ZoomingPDFViewerForIPadViewController : UIViewController <UIScrollViewDelegate,PDFScrollViewDelegate> {
CGPDFPageRef page;
CGPDFDocumentRef pdf;
NSInteger currentPage;
NSInteger pageCount;
PDFScrollView *myScrollView;
PDFScrollView *previousPage;
PDFScrollView *nextPage;
}
-(id)initWithResourcePath:(NSString*)path ;
-(void)loadNextPage;
-(void)loadPreviousPage;
@end
@implementation ZoomingPDFViewerForIPadViewController
// some more code
#pragma mark -
#pragma mark PDFScrollViewDelegate methods
/*
called when user swipes right on the view
*/
-(void)viewDetectedRightSwipe:(PDFScrollView*)pdfScrollView withGesture:(UISwipeGestureRecognizer*)recognizer {
NSLog(@"right");
if (currentPage>1){
//decreate page counter
currentPage--;
// release old next page
if(nextPage){
[nextPage release];
}
// set the actual page as the next one
nextPage = [myScrollView retain];
// remove the view from the actual view
[myScrollView removeFromSuperview];
// check if the previous page is loaded
if(!previousPage)
[self loadPreviousPage];
// set the previouse page as the actual page
myScrollView = previousPage;
myScrollView.pdfViewDelegate = self;
//[myScrollView drawPage];
// load a new previous page
//[NSThread detachNewThreadSelector:@selector(loadNextPage) toTarget:self withObject:nil];
//[self loadNextPage];
}
}
/*
called when user swipes left on the view
*/
-(void)viewDetectedLeftSwipe:(PDFScrollView*)pdfScrollView withGesture:(UISwipeGestureRecognizer*)recognizer{
NSLog(@"left");
// if the end of the document isn't reached
if (currentPage<pageCount){
//increment current page
currentPage++;
// if a previous page has been loaded release it
if (previousPage) {
[previousPage release];
}
// assing the actual view to as a previous page and retain it before it gets release by superview
previousPage = [myScrollView retain];
// remove the view from the super view
[myScrollView removeFromSuperview];
// if a next page hasn't beeen loaded yet, load it on this thread
if (!nextPage)
[self loadNextPage];
// assign the next page as the current page
myScrollView = nextPage;
// put the current page the delegate
myScrollView.pdfViewDelegate = self;
// add the current page to the super view
[[self view] addSubview:myScrollView];
// load a next page.
[NSThread detachNewThreadSelector:@selector(loadNextPage) toTarget:self withObject:nil];
//[self loadNextPage];
}
}
/*
called when the user taps the screen
*/
-(void)viewDetectedTapping:(PDFScrollView*)pdfScrollView withGesture:(UITapGestureRecognizer*)recognizer {
NSLog(@"tapped");
[myScrollView setZoomScale:1.0f animated:YES];
}
-(void)loadNextPage {
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
CGPDFPageRef aPage = CGPDFDocumentGetPage(pdf, currentPage+1);
nextPage = [[PDFScrollView alloc] initWithFrame:myScrollView.frame andPDFPage:aPage ];
[pool release];
}
-(void)loadPreviousPage {
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
CGPDFPageRef aPage = CGPDFDocumentGetPage(pdf, currentPage-1);
previousPage = [[PDFScrollView alloc] initWithFrame:myScrollView.frame andPDFPage:aPage];
[pool release];
}
@end
这是手势触发的代码。
-(void)handleRightSwipe:(UIGestureRecognizer*)gesture {
if ([pdfViewDelegate respondsToSelector:@selector(viewDetectedRightSwipe:withGesture:)]) {
UISwipeGestureRecognizer *swipe = (UISwipeGestureRecognizer*)gesture;
[pdfViewDelegate viewDetectedRightSwipe:self withGesture:swipe];
}
}
-(void)handleLeftSwipe :(UIGestureRecognizer*)gesture{
if ([pdfViewDelegate respondsToSelector:@selector(viewDetectedLeftSwipe:withGesture:)]) {
UISwipeGestureRecognizer *swipe= (UISwipeGestureRecognizer*)gesture;
[pdfViewDelegate viewDetectedLeftSwipe:self withGesture:swipe];
}
}
提前感谢您的时间
推荐答案
在iOS 4.xx上有一个错误，导致回调如果你在回调中删除了OverSuperview，你会被调用两次。
On iOS 4.x.x there is a bug, which caused the callback to be called twice if you removeFromSuperview inside callback.
你可以在removeFromSuperview中将enabled属性设置为NO：
You can set enabled property to NO in removeFromSuperview:
- (void)removeFromSuperview
{
for(UIGestureRecognizer* gestureRecognizer in self.gestureRecognizers) {
gestureRecognizer.enabled = NO;
}
[super removeFromSuperview];
}
- (void)willMoveToSuperview:(UIView *)newSuperview
{
for(UIGestureRecognizer* gestureRecognizer in self.gestureRecognizers) {
gestureRecognizer.enabled = YES;
}
[super willMoveToSuperview:newSuperview];
}
但是，即使被禁用，回调仍会触发。
所以你应该在回调中检查启用的属性：
However, the callback will still fire, even if it is disabled. So you should then check enabled property in callback:
- (void)didSwipeRight:(UISwipeGestureRecognizer *)gestureRecognizer
{
if (gestureRecognizer.enabled) {
//do something useful...
}
}
这篇关于UISwipeGestureRecognizer调用了两次的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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