UIPanGestureRecognizer - 仅垂直或水平 [英] UIPanGestureRecognizer - Only vertical or horizontal

问题描述

我有一个视图，它有一个 UIPanGestureRecognizer 来垂直拖动视图。所以在识别器回调中，我只更新y坐标来移动它。这个视图的超级视图有一个 UIPanGestureRecognizer ，它将水平拖动视图，只是更新x坐标。

I have a view that has a UIPanGestureRecognizer to drag the view vertically. So in the recognizer callback, I only update the y-coordinate to move it. The superview of this view, has a UIPanGestureRecognizer that will drag the view horizontally, just updating the x-coordinate.

问题是第一个 UIPanGestureRecognizer 正在使用该事件垂直移动视图，因此我无法使用超视图手势。

The problem is that the first UIPanGestureRecognizer is taking the event to move the view vertically, so I can not use the superview gesture.

我试过

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer
 shouldRecognizeSimultaneouslyWithGestureRecognizer:
                            (UIGestureRecognizer *)otherGestureRecognizer;

两者都有效，但我不希望这样。我希望只有在运动明显水平的情况下才能检测水平。因此，如果 UIPanGestureRecognizer 具有direction属性，那就太棒了。

and both will work, but I don't want that. I want the horizontally to be detected only if the movement is clearly horizontal. So it would be great if the UIPanGestureRecognizer had a direction property.

如何实现此行为？我发现这些文档非常令人困惑，所以也许有人可以在这里更好地解释它。

How can I achieve this behavior? I find the docs very confusing, so maybe someone can explain it better here.

推荐答案

我想出了创建UIPanGestureRecognizer的子类

I figured it out creating a subclass of UIPanGestureRecognizer

DirectionPanGestureRecognizer：

DirectionPanGestureRecognizer:

#import <Foundation/Foundation.h>
#import <UIKit/UIGestureRecognizerSubclass.h>

typedef enum {
    DirectionPangestureRecognizerVertical,
    DirectionPanGestureRecognizerHorizontal
} DirectionPangestureRecognizerDirection;

@interface DirectionPanGestureRecognizer : UIPanGestureRecognizer {
    BOOL _drag;
    int _moveX;
    int _moveY;
    DirectionPangestureRecognizerDirection _direction;
}

@property (nonatomic, assign) DirectionPangestureRecognizerDirection direction;

@end

DirectionPanGestureRecognizer.m：

DirectionPanGestureRecognizer.m:

#import "DirectionPanGestureRecognizer.h"

int const static kDirectionPanThreshold = 5;

@implementation DirectionPanGestureRecognizer

@synthesize direction = _direction;

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
    [super touchesMoved:touches withEvent:event];
    if (self.state == UIGestureRecognizerStateFailed) return;
    CGPoint nowPoint = [[touches anyObject] locationInView:self.view];
    CGPoint prevPoint = [[touches anyObject] previousLocationInView:self.view];
    _moveX += prevPoint.x - nowPoint.x;
    _moveY += prevPoint.y - nowPoint.y;
    if (!_drag) {
        if (abs(_moveX) > kDirectionPanThreshold) {
            if (_direction == DirectionPangestureRecognizerVertical) {
                self.state = UIGestureRecognizerStateFailed;
            }else {
                _drag = YES;
            }
        }else if (abs(_moveY) > kDirectionPanThreshold) {
            if (_direction == DirectionPanGestureRecognizerHorizontal) {
                self.state = UIGestureRecognizerStateFailed;
            }else {
                _drag = YES;
            }
        }
    }
}

- (void)reset {
    [super reset];
    _drag = NO;
    _moveX = 0;
    _moveY = 0;
}

@end

这只会触发手势如果用户开始拖动所选行为。将direction属性设置为正确的值，您就可以设置。

This will only trigger the gesture if the user starts dragging in the selected behavior. Set the direction property to a correct value and you are all set.

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