Objective c UISweepGestureRecognitor调用了两次

我在实现一个视图时遇到了问题

这是一个在CATiledLayer中显示pdf页面的视图。该平铺视图位于UISCrollView中

我将视图控制为“ZoomingPDFView”苹果示例。我做了一些修改，以便它能够识别未启用滚动时的滑动手势，以及该站点上各种线程和问题中的建议。当时，这些手势被称为一次。但是，当我需要分离视图并将滑动委托给缓存页面和执行多功能视图时，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

现在我在一边有了视图，在另一边有了控制器，滑动手势被检测到两次，我甚至连问题的线索都找不到

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

代码如下：

#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

---

提前感谢您抽出时间

在将手势传递给学员之前，请尝试检查手势的状态属性：

-(void)handleRightSwipe:(UIGestureRecognizer*)gesture {
    if (gesture.state != UIGestureRecognizerStateEnded)
        return; //gesture not finished yet

    if ([pdfViewDelegate respondsToSelector:@selector(viewDetectedRightSwipe:withGesture:)]) {
        UISwipeGestureRecognizer *swipe = (UISwipeGestureRecognizer*)gesture;
        [pdfViewDelegate viewDetectedRightSwipe:self withGesture:swipe];
    }
}

---

如果可以的话，用左扫也可以。

当用户检测到手势正在“完成”时，AbitoBevious的回答是好的，但它确实是开始深入研究问题的好地方。这里的问题是，手势本身被检测到一次，但与之相关的动作被触发两次。我做了一个计时器来跟踪这些调用之间的毫秒数，以忽略对操作的假调用。

@Pacu

不要用定时器

您需要查看手势状态。UIGestureRecognizer会向您发送有关您得到的手势的哪一部分的信息。手势不是一个单一的事件。想想一个捏的姿势。。。它不会只发生一次，它会开始、改变位置，并且可以被取消、失败或结束。每次这些事情发生时，您的回调都会运行

仅仅忽略发生在一起的事件通常会起作用，但例如，一个滑动手势可能会持续比您的时间窗口更长的时间

switch (sender.state) {
    case UIGestureRecognizerStateBegan:
        self.dragging = [self objectToRotateOrPinch:sender];
        break;
    case UIGestureRecognizerStateEnded:
        self.dragging = nil;
        break;
    case UIGestureRecognizerStateCancelled:
        self.dragging = nil;
        break;
    case UIGestureRecognizerStateFailed:
        self.dragging = nil;
        break;
    case UIGestureRecognizerStateChanged:
        // rotate or pinch
        break;
    default:
        break;
}

---

如果您关心的只是刷卡发生的时间，那么您只希望在state==UIGestureRecognitizerStateEnded时做出反应。

我遇到了完全相同的问题，我猜第二个操作是在执行此行时触发的：

[myScrollView removeFromSuperview];

由于某些原因，当它所附加到的视图被删除时，UISweepGestureRecognizer会触发。似乎没有其他UIgestureRecognitor执行此操作

我的解决方案是在调用removeFromSuperview之前禁用所有手势识别器：

for (UIGestureRecognizer *g in myScrollView.gestureRecognizers) {
    g.enabled = NO;
    g.delegate = nil;
}
[myScrollView 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];
}

---

这并不理想，但它成功了。

下面的代码是一个简单的解决方法，我认为它不太可能有任何不必要的副作用

- (void) leftSwipe: (UISwipeGestureRecognizer *) recognizer;
{
    if (![recognizer isEnabled]) return;    
    [recognizer setEnabled:NO];
    [recognizer performSelector:@selector(setEnabled:) withObject: [NSNumber numberWithBool:YES] afterDelay:0.1];
       // your gesture handling code here....

---

当我从使用通知接收手势切换到直接接收手势时，我遇到了这个问题，但我没有进一步研究这个问题。state属性对我毫无帮助-日志显示识别器在同一状态下提供的第一次和第二次调用。

我也有同样的问题，似乎在尝试删除视图（手势触发）时出现了问题，因此，重写removeFromSuperview。。。这个小剪适合我

- (void)removeFromSuperview
{
    for(UIGestureRecognizer* gesture in [self gestureRecognizers])
        [self removeGestureRecognizer:gesture];
    [super removeFromSuperview];
}

---

我遇到了完全相同的问题，您还可以向UIView类发送

RemovegestureRecognitizer:

消息

-(void)handleLeftSwipe:(UIGestureRecognizer *)gesture
{
    UIView *vw = [gesture view];
    [view removeGestureRecognizer:gesture];
    [view removeFromSuperview];
}

但是，我仍然不知道当视图从superview中删除时，为什么会“触发”该手势

---

干杯，

在iOS 4.x.x上有一个bug，如果您在回调中从SuperView中移除，则会导致回调调用两次

您可以在removeFromSuperview中将enabled属性设置为NO：

for (UIGestureRecognizer *g in myScrollView.gestureRecognizers) {
    g.enabled = NO;
    g.delegate = nil;
}
[myScrollView 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，即使已禁用，回调仍将启动。 因此，您应该在回调中检查enabled属性：

- (void)didSwipeRight:(UISwipeGestureRecognizer *)gestureRecognizer
{
    if (gestureRecognizer.enabled) {
            //do something useful...
    }
}

---

请显示HandleLightSwipe和/或HandleLeftsSwipe的代码。我刚刚做了编辑。谢谢（顺便说一句，非常棒的用户名）曾经奏效过。该手势似乎已结束，然后该方法被触发两次。这在我上一次谷歌搜索中出现（使用相同的术语：S），请尝试将状态检查放入手势处理程序中。另外，请确保仅将手势识别器添加到视图中一次。有没有可能启用手势被多次调用？我要试试肯尼。谢谢我也不喜欢计时器嘿，肯尼，我已经试过了，而且手势识别器似乎只是通知“结束”状态，而不是“中间”状态，如更改、失败、取消。被解雇的是两个“结束”状态。您所说的“UILongpressGestureRecognizer”是正确的，但事实似乎并非如此。我一直在观察这一点，Jeff，在我的情况下，这似乎是可能的，但控制台输出显示了其他情况。不管怎样，我已经尝试了很多方法，我也将尝试一下您的解决方法。我在使用SDK 4.2时看到了完全相同的情况：如果视图从superview中删除，将再次触发滑动！奇怪，我也证实了这一点。看起来像一个bug。这个bug在iOS 4.3而不是5.0上表现出来。不过，你的解决方案在4.3上不起作用。这个bug仍然存在于iOS 12中！英雄联盟不错的解决方案，顺便说一下！：）