我已经毫无问题地创建了几个自定义 UIGestureRecognizers。我决定我想要一个自定义版本的单击手势，然后开始对 UIGestureRecognizer 进行子类化。除了一个问题外，一切似乎都很好。在我的操作处理程序 [gestureRecognizer locationInView:self] 中，x 和 y 始终返回零。当我回到 UITapGestureRecognizer 时， Action 处理程序工作正常。这一定与子类手势识别器有关，这是我的代码:

#import "gr_TapSingle.h"

#define tap_Timeout 0.25

@implementation gr_TapSingle


- (id)init
{
    self = [super init];
    if ( self )
    {
    }
    return self;
}

- (void)reset
{
}

-(void)gesture_Fail
{
    self.state = UIGestureRecognizerStateFailed;
}

-(void)touchesBegan:(NSSet*)touches withEvent:(UIEvent*)event
{
    [super touchesBegan:touches withEvent:event];

    if ( [self numberOfTouches] > 1 )
    {
        self.state = UIGestureRecognizerStateFailed;
        return;
    }

    originLocation = [[[event allTouches] anyObject] locationInView:self.view];

    [self performSelector:@selector(gesture_Fail) withObject:nil afterDelay:tap_Timeout];
}

-(void)touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event
{
    [super touchesMoved:touches withEvent:event];

    if ( self.state == UIGestureRecognizerStatePossible )
    {
        CGPoint l_Location = [[[event allTouches] anyObject] locationInView:self.view];
        CGPoint l_Location_Delta = CGPointMake( l_Location.x - originLocation.x, l_Location.y - originLocation.y );
        CGFloat l_Distance_Delta = sqrt( l_Location_Delta.x * l_Location_Delta.x + l_Location_Delta.y * l_Location_Delta.y );
        if ( l_Distance_Delta > 15 )
            self.state = UIGestureRecognizerStateFailed;
        return;
    }
}

-(void)touchesEnded:(NSSet*)touches withEvent:(UIEvent*)event
{
    [super touchesEnded:touches withEvent:event];

    if ( self.state == UIGestureRecognizerStatePossible )
        [[self class] cancelPreviousPerformRequestsWithTarget:self selector:@selector(gesture_Fail) object:nil];

    if ( self.state != UIGestureRecognizerStateFailed )
        self.state = UIGestureRecognizerStateEnded;
}

-(void)touchesCancelled:(NSSet*)touches withEvent:(UIEvent*)event
{
    [super touchesCancelled:touches withEvent:event];
    if ( self.state == UIGestureRecognizerStatePossible )
        [[self class] cancelPreviousPerformRequestsWithTarget:self selector:@selector(gesture_Fail) object:nil];
    self.state = UIGestureRecognizerStateFailed;
}

@end

最佳答案

Apple 的文档说:

The returned value is a generic single-point location for the gesture computed by the UIKit framework. It is usually the centroid of the touches involved in the gesture. For objects of the UISwipeGestureRecognizer and UITapGestureRecognizer classes, the location returned by this method has a significance special to the gesture. This significance is documented in the reference for those classes.

所以我假设每个子类都有自己的这个方法的特殊实现，适合自己的特点。所以如果你想子类化 UIGestureRecognizer，你必须自己实现它。

编辑:

类似于:

- (CGPoint)locationInView:(UIView *)view
{
   if(view == self.view)
   {
      return originLocation;
   }
   else
   {
     //you decide
   }
}

关于iphone - 创建自定义 UIGestureRecognizer，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/10320641/