iOS实现应用悬浮窗效果

//悬浮窗测试
//创建一个悬浮窗口
mwindow = [[AssistiveTouch alloc]initWithFrame:CGRectMake(100, 200, 40, 40) imageName:@"1.png"];
//ios9 window要设置rootview 不然崩溃
UIViewController *controller = [[UIViewController alloc] init];
mwindow.rootViewController = controller;
//展示悬浮窗。。
[self.window makeKeyAndVisible];

//添加移动的手势
UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(locationChange:)];
 pan.delaysTouchesBegan = YES;
 [self addGestureRecognizer:pan];

//改变位置
-(void)locationChange:(UIPanGestureRecognizer*)p
{
    //[[UIApplication sharedApplication] keyWindow]
    CGPoint panPoint = [p locationInView:[[UIApplication sharedApplication] keyWindow]];
    if(p.state == UIGestureRecognizerStateBegan)
    {
        [NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(changeColor) object:nil];
        _imageView.alpha = 0.8;
    }
    else if (p.state == UIGestureRecognizerStateEnded)
    {
        [self performSelector:@selector(changeColor) withObject:nil afterDelay:4.0];
    }
    if(p.state == UIGestureRecognizerStateChanged)
    {
        self.center = CGPointMake(panPoint.x, panPoint.y);
    }
    else if(p.state == UIGestureRecognizerStateEnded)
    {
        if(panPoint.x <= kScreenWidth/2)
        {
            if(panPoint.y <= 40+HEIGHT/2 && panPoint.x >= 20+WIDTH/2)
            {
                [UIView animateWithDuration:0.2 animations:^{
                    self.center = CGPointMake(panPoint.x, HEIGHT/2);
                }];
            }
            else if(panPoint.y >= kScreenHeight-HEIGHT/2-40 && panPoint.x >= 20+WIDTH/2)
            {
                [UIView animateWithDuration:0.2 animations:^{
                    self.center = CGPointMake(panPoint.x, kScreenHeight-HEIGHT/2);
                }];
            }
            else if (panPoint.x < WIDTH/2+15 && panPoint.y > kScreenHeight-HEIGHT/2)
            {
                [UIView animateWithDuration:0.2 animations:^{
                    self.center = CGPointMake(WIDTH/2, kScreenHeight-HEIGHT/2);
                }];
            }
            else
            {
                CGFloat pointy = panPoint.y < HEIGHT/2 ? HEIGHT/2 :panPoint.y;
                [UIView animateWithDuration:0.2 animations:^{
                    self.center = CGPointMake(WIDTH/2, pointy);
                }];
            }
        }
        else if(panPoint.x > kScreenWidth/2)
        {
            if(panPoint.y <= 40+HEIGHT/2 && panPoint.x < kScreenWidth-WIDTH/2-20 )
            {
                [UIView animateWithDuration:0.2 animations:^{
                    self.center = CGPointMake(panPoint.x, HEIGHT/2);
                }];
            }
            else if(panPoint.y >= kScreenHeight-40-HEIGHT/2 && panPoint.x < kScreenWidth-WIDTH/2-20)
            {
                [UIView animateWithDuration:0.2 animations:^{
                    self.center = CGPointMake(panPoint.x, 480-HEIGHT/2);
                }];
            }
            else if (panPoint.x > kScreenWidth-WIDTH/2-15 && panPoint.y < HEIGHT/2)
            {
                [UIView animateWithDuration:0.2 animations:^{
                    self.center = CGPointMake(kScreenWidth-WIDTH/2, HEIGHT/2);
                }];
            }
            else
            {
                CGFloat pointy = panPoint.y > kScreenHeight-HEIGHT/2 ? kScreenHeight-HEIGHT/2 :panPoint.y;
                [UIView animateWithDuration:0.2 animations:^{
                    self.center = CGPointMake(320-WIDTH/2, pointy);
                }];
            }
        }
    }
}