Question

我正在尝试在我的ViewController（有一个tableView）中实现两个必须一个接一个地工作的手势识别器。第一个是向下滑动手势，第二个是长按手势。

这是我用@sergio建议修改的代码

    - (void)viewDidLoad
    {
        [super viewDidLoad];

        swipeDown = [[[UISwipeGestureRecognizer alloc]initWithTarget:self action:@selector(swipeDownAction)] autorelease];

        longPress = [[[CustomLongPress alloc]initWithTarget:self action:@selector(longPressAction)] autorelease];


        longPress.minimumPressDuration = 2;

        swipeDown.numberOfTouchesRequired = 1;

        swipeDown.direction = UISwipeGestureRecognizerDirectionDown;


       swipeDown.delegate = self ;

        longPress.delegate = self ;

        [myTableView addGestureRecognizer:swipeDown];

        [myTableView addGestureRecognizer:longPress];





  }


    -(void)swipeDownAction {

        _methodHasBeenCalled = YES;    // bool @property declared in .h

        NSLog(@"Swipe down detected");


    }



    -(void)longPressAction {

        NSLog(@"long press detected");
    }

    - (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
    {
        return YES;
    }

我的UILongPressGestureRecognizer子类：

#import "CustomLongPress.h"
#import "ViewController.h"


@interface CustomLongPress()
{

    ViewController *vc;
}

@end


@implementation CustomLongPress
-(id)initWithTarget:(id)target action:(SEL)action controller:(ViewController *)viewCon
{
    self = [super initWithTarget:target action:action];

    if (self) {

        vc = viewCon;

    }

    return self;
}


-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
     NSLog(vc.methodHasBeenCalled ? @"Yes" : @"No");

    if (vc.methodHasBeenCalled) {

        [super touchesBegan:touches withEvent:event];
    }
}

不幸的是，我仍然只从swipeDown获取日志，但是当涉及到longPress时没有日志

Answer 1

为此你需要创建自己的自定义手势识别器。最好的方法是让你继续UILongPressGestureRecognizer，并在刷卡结束后让它“接受”长按。例如，在touchesBegan方法

中

- (void)touchesBegan:(NSSet*)touches withEvent:(UIEvent*)event {
   <if swipe recognizer action method has been called>
       [super touchesBegan:touches withEvent:event];
   }
}

通过这种方式，两个手势识别器都会尝试识别手势：滑动识别器会立即这样做;而自定义识别器会“等待”滑动识别器触发。

实现条件<if swipe recognizer action method has been called>的简单方法是在滑动操作中设置全局标记（在执行滑动操作时设置它;然后自定义识别器读取其值）。这是 easy ，到目前为止还不是您能找到的最佳实现。

另一种方法是依靠requiresGestureRecognizerToFail链接3个标准手势识别器，我们称之为A，B和C，其中：

A是UISwipeGestureRecognizer;
C是UILongPressGestureRecognizer;
B是任何手势识别器。

您可以像这样配置它们：

C --> B --> A

x --> y表示x要求y失败。因此，您C（您的长按手势识别器）将需要B GR失败并且B要求A（您的滑动识别器）失败;只要B识别出滑动，A就会失败;一旦B失败，C将被允许识别长按（如果有的话）。

编辑：

阅读完您的评论后，您是否介意尝试一下，看看是否有帮助：

删除被覆盖的touchesBegan并将其替换为：

- (void)touchesBegan:(NSSet*)touches withEvent:(UIEvent*)event {
}

然后定义：

- (void)touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event {

  if (vc.methodHasBeenCalled) {
    [super touchesBegan:touches withEvent:event];
  } else {
     return;
  }
}

如果这不起作用，那么让自定义手势识别器继承自通用手势识别器和

保留touchesBegan:并将touchesMoved替换为：

- (void)touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event {

  self.lastTouch = [touches anyObject];
  if (vc.methodHasBeenCalled && self.gestureNotBegunYet == YES) {
    self.gestureNotBegunYet = NO;
    [self performSelector:@selector(recognizeLongPress) withObject:nil afterDelay:1.0];

  } else {
     return;
  }
}

并添加：

- (float)travelledDistance {
  CGPoint currentLocation = [self.lastTouch locationInView:self.view.superview];
  return sqrt(pow((currentLocation.x - self.initialLocation.x), 2.0) +
            pow((currentLocation.y - self.initialLocation.y), 2.0));
}

- (void)fail {
  self.gestureNotBegunYet = YES;
  [NSObject cancelPreviousPerformRequestsWithTarget:self];

}

- (void)recognizeLongPress {

  if ([self travelledDistance] < kTapDragThreshold) {
    self.longPressed = YES;
    self.state = UIGestureRecognizerStateChanged;
  } else {
        [self fail];
        self.state = UIGestureRecognizerStateFailed;
  }
}

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

- (void)touchesCancelled:(NSSet*)touches withEvent:(UIEvent*)event {
  [self fail];
  [super touchesCancelled:touches withEvent:event];
}

您需要在.h

@property(nonatomic) CGPoint initialLocation;
@property(nonatomic, retain) UITouch* lastTouch;
@property(nonatomic) BOOL gestureNotBegunYet;

Answer 2

如果我没有弄错的话，一旦系统检测到特定类型的手势（轻击，轻扫，平移，长按等），它就不能再为该触摸动作发送不同类型的手势。

这并不妨碍您达到预期的效果。也许是重载以下UIResponder方法的组合：

– touchesBegan:withEvent:
– touchesMoved:withEvent:
– touchesEnded:withEvent:
– touchesCancelled:withEvent:

使用手势识别器（不确定输入是否被一个人消耗而被其他人忽略），您可以确定它是“长扫描”

滑动和长按相结合

2 个答案: