类似assistive touch实现的方法

需求

按钮跟随手指移动，松开后停留在最左边和最右边，顶部挨着状态栏，顶部挨着tabbar

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实现思路

视图添加平移手势，移动过程中即时改变视图的位置，结束后判断停留位置进行悬停

代码

 UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(touchPan:)];
    [button addGestureRecognizer:panGestureRecognizer];

- (void)touchPan:(UIPanGestureRecognizer*)recognizer{
    
    UIView *touchView = recognizer.view;
    
    //拿到变化后的点 即时更新视图的位置
    CGPoint translation = [recognizer translationInView:self.view];
    CGFloat centerX = touchView.center.x + translation.x;
    CGFloat centerY = touchView.center.y+ translation.y;
    touchView.center = CGPointMake(centerX,centerY);
    //位移清零 让按钮只移动变化的量
    [recognizer setTranslation:CGPointZero inView:self.view];
    
    
    CGFloat ScreenWidth = [[UIScreen mainScreen] bounds].size.width;
    CGFloat ScreenHeight = [[UIScreen mainScreen] bounds].size.height;
    CGFloat finalCenterX;
    CGFloat finalCenterY = centerY;
    CGFloat touchViewCenterX = touchView.frame.size.width * 0.5;
    CGFloat touchViewCenterY = touchView.frame.size.height * 0.5;
    //结束后做左右上下悬浮处理
    if(recognizer.state == UIGestureRecognizerStateEnded|| recognizer.state == UIGestureRecognizerStateCancelled) {
        
        if(centerX > ScreenWidth * 0.5) {//停留右边
            
            finalCenterX = ScreenWidth - touchViewCenterX;
            
        }else{//停留左边
            
            finalCenterX = touchViewCenterX;
            
        }
        
        //固定最高和最低的位置
        if (centerY < touchViewCenterY + 20) {//顶部留出状态栏的位置
            finalCenterY = touchViewCenterY + 20;
        }
        
        if (centerY > ScreenHeight - 49) {//底部留出tabbar的位置
            finalCenterY = ScreenHeight - 49 - touchViewCenterY;
        }
        
        
        [UIView animateWithDuration:0.3 animations:^{
            
            touchView.center = CGPointMake(finalCenterX,finalCenterY);
            
        }];
        
    }
    
}

参考链接:https://www.jianshu.com/p/29481c868774?open_source=weibo_search