如何限制 UIPanGestureRecognizer 仅在角落工作

Posted 2023-03-12

【中文标题】如何限制 UIPanGestureRecognizer 仅在角落工作

【英文标题】：How to limit the UIPanGestureRecognizer to work on corners only

【发布时间】：2013-07-02 09:41:00

【问题描述】：

我正在尝试在两个方向上滑动视图，并且以下代码对于整个视图都可以正常工作，但是我需要此平移手势仅适用于左右角，每边仅说 50 像素，并且忽略手势如果它不在角落里。

请帮忙

-(void)setupGestures 
UIPanGestureRecognizer *panRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(movePanel:)];
[panRecognizer setMinimumNumberOfTouches:1];
[panRecognizer setMaximumNumberOfTouches:1];
[panRecognizer setDelegate:self];

[_centerViewController.view addGestureRecognizer:panRecognizer];
 

-(void)movePanel:(id)sender 
[[[(UITapGestureRecognizer*)sender view] layer] removeAllAnimations];

CGPoint translatedPoint = [(UIPanGestureRecognizer*)sender translationInView:self.view];
CGPoint velocity = [(UIPanGestureRecognizer*)sender velocityInView:[sender view]];

if([(UIPanGestureRecognizer*)sender state] == UIGestureRecognizerStateBegan) 
    UIView *childView = nil;

    if(velocity.x > 0) 
        if (!_showingRightPanel) 
            childView = [self getLeftView];
        
     else 
        if (!_showingLeftPanel) 
            childView = [self getRightView];
        

    
    // make sure the view we're working with is front and center
    [self.view sendSubviewToBack:childView];
    [[sender view] bringSubviewToFront:[(UIPanGestureRecognizer*)sender view]];


if([(UIPanGestureRecognizer*)sender state] == UIGestureRecognizerStateEnded) 

    if(velocity.x > 0) 
        // NSLog(@"gesture went right");
     else 
        // NSLog(@"gesture went left");
    

    if (!_showPanel) 
        [self movePanelToOriginalPosition];
     else 
        if (_showingLeftPanel) 
            [self movePanelRight];
          else if (_showingRightPanel) 
            [self movePanelLeft];
        
    


if([(UIPanGestureRecognizer*)sender state] == UIGestureRecognizerStateChanged) 
    if(velocity.x > 0) 
        // NSLog(@"gesture went right");
     else 
        // NSLog(@"gesture went left");
    

    // are we more than halfway, if so, show the panel when done dragging by setting this value to YES (1)
    _showPanel = abs([sender view].center.x - _centerViewController.view.frame.size.width/2) > _centerViewController.view.frame.size.width/2;

    // allow dragging only in x coordinates by only updating the x coordinate with translation position
    [sender view].center = CGPointMake([sender view].center.x + translatedPoint.x, [sender view].center.y);
    [(UIPanGestureRecognizer*)sender setTranslation:CGPointMake(0,0) inView:self.view];

    // if you needed to check for a change in direction, you could use this code to do so
    if(velocity.x*_preVelocity.x + velocity.y*_preVelocity.y > 0) 
        // NSLog(@"same direction");
     else 
        // NSLog(@"opposite direction");
    

    _preVelocity = velocity;

【问题讨论】：

为什么不创建自定义手势识别器来封装逻辑？

【参考方案1】：

使用yourView.frame 获取UIView 的四个角 然后，获取UIView 内的接触点。 查看触摸点和四个角中的每一个之间的差异。 如果四个值中的任何一个小于 50（例如），请在通过 UIPanGestureRecognizer 调用的方法中执行您想要的操作。

你可以通过触摸点

CGPoint currentlocation = [recognizer locationInView:self.view];

你可以通过四个角，

CGPoint topLeft = view.bounds.origin;
topLeft = [[view superview] convertPoint:topLeft fromView:view];

CGPoint topRight = CGPointMake(view.bounds.origin.x + view.bounds.width, view.bounds.origin.y);
topRight = [[view superview] convertPoint:topRight fromView:view];

// and so on.

通过这个方法可以求出两点之间的距离，

- (double) getDistance:(CGPoint)one :(CGPoint)two

    return sqrt((two.x - one.x)*(two.x - one.x) + (two.y - one.y)*(two.y - one.y));

希望这会有所帮助（-：

【参考方案2】：

覆盖UIView 中的- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event 方法，如下所示

- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event

    BOOL pointInside = NO;

    if(CGRectContainsPoint(self.bounds, point) && ((point.x < 50) || (point.x > self.bounds.size.width-50)))
    
        pointInside = YES;
    

    return pointInside;

希望对你有帮助。