iOS悬浮、可拖动、自动吸附屏幕边缘的按钮制作

想制作一个按钮，类似于iPhone 的辅助touch的那个小白点的按钮。但是注意：千万不能也做成小白点，可能会导致审核被拒。

不明白网络上查到的那些，为什么会那么复杂，涉及到那么多的页面。其实只要在要出现这个按钮的控制器的.m文件里写几段代码就可以解决，非常轻便，尤其适合开发新手。

首先，在想放这个button的vc里，创建一个成员对象。

@property (nonatomic,strong)UIButton *spButton

然后就可以开始创建按钮了，我写成了一个方法：

        //创建可拖动、自动贴近边缘的 事件上报按钮
        [self initAddEventBtn];

方法的具体内容：

-(void)initAddEventBtn{
    UIButton *btn = [[UIButton alloc] initWithFrame:CGRectMake(SCREEN_WIDTH-71,300,66,66)];
    [btn setImage:[UIImage imageNamed:@"shijianshangbao"]  forState:UIControlStateNormal];
    btn.backgroundColor = [UIColor colorWithWhite:0.88 alpha:0.8];
    btn.tag = 0;
    btn.layer.cornerRadius = 8;
    [self.view addSubview:btn];
    self.spButton = btn;
    [_spButton addTarget:self action:@selector(addEvent:) forControlEvents:UIControlEventTouchUpInside];
    //添加手势
    UIPanGestureRecognizer *panRcognize=[[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePanGesture:)];
    [panRcognize setMinimumNumberOfTouches:1];
    [panRcognize setEnabled:YES];
    [panRcognize delaysTouchesEnded];
    [panRcognize cancelsTouchesInView];
    [btn addGestureRecognizer:panRcognize];
}

醉关键的部分来了，实现按钮的移动事件处理：

- (void)handlePanGesture:(UIPanGestureRecognizer *)recognizer
{
    //移动状态
    UIGestureRecognizerState recState =  recognizer.state;
    
    switch (recState) {
        case UIGestureRecognizerStateBegan:
            
            break;
        case UIGestureRecognizerStateChanged:
        {
            CGPoint translation = [recognizer translationInView:self.navigationController.view];
            recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x, recognizer.view.center.y + translation.y);
        }
            break;
        case UIGestureRecognizerStateEnded:
        {
            CGPoint stopPoint = CGPointMake(0, SCREEN_HEIGHT / 2.0);
            
            if (recognizer.view.center.x < SCREEN_WIDTH / 2.0) {
                if (recognizer.view.center.y <= SCREEN_HEIGHT/2.0) {
                    //左上
                    if (recognizer.view.center.x  >= recognizer.view.center.y) {
                        stopPoint = CGPointMake(recognizer.view.center.x, self.spButton.width/2.0);
                    }else{
                        stopPoint = CGPointMake(self.spButton.width/2.0, recognizer.view.center.y);
                    }
                }else{
                    //左下
                    if (recognizer.view.center.x  >= SCREEN_HEIGHT - recognizer.view.center.y) {
                        stopPoint = CGPointMake(recognizer.view.center.x, SCREEN_HEIGHT - self.spButton.width/2.0);
                    }else{
                        stopPoint = CGPointMake(self.spButton.width/2.0, recognizer.view.center.y);
//                        stopPoint = CGPointMake(recognizer.view.center.x, SCREEN_HEIGHT - self.spButton.width/2.0);
                    }
                }
            }else{
                if (recognizer.view.center.y <= SCREEN_HEIGHT/2.0) {
                    //右上
                    if (SCREEN_WIDTH - recognizer.view.center.x  >= recognizer.view.center.y) {
                        stopPoint = CGPointMake(recognizer.view.center.x, self.spButton.width/2.0);
                    }else{
                        stopPoint = CGPointMake(SCREEN_WIDTH - self.spButton.width/2.0, recognizer.view.center.y);
                    }
                }else{
                    //右下
                    if (SCREEN_WIDTH - recognizer.view.center.x  >= SCREEN_HEIGHT - recognizer.view.center.y) {
                        stopPoint = CGPointMake(recognizer.view.center.x, SCREEN_HEIGHT - self.spButton.width/2.0);
                    }else{
                        stopPoint = CGPointMake(SCREEN_WIDTH - self.spButton.width/2.0,recognizer.view.center.y);
                    }
                }
            }
            
            //如果按钮超出屏幕边缘
            if (stopPoint.y + self.spButton.width+40>= SCREEN_HEIGHT) {
                stopPoint = CGPointMake(stopPoint.x, SCREEN_HEIGHT - self.spButton.width/2.0-49);
                NSLog(@"超出屏幕下方了！！"); //这里注意iphoneX的适配。。X的SCREEN高度算法有变化。
            }
            if (stopPoint.x - self.spButton.width/2.0 <= 0) {
                stopPoint = CGPointMake(self.spButton.width/2.0, stopPoint.y);
            }
            if (stopPoint.x + self.spButton.width/2.0 >= SCREEN_WIDTH) {
                stopPoint = CGPointMake(SCREEN_WIDTH - self.spButton.width/2.0, stopPoint.y);
            }
            if (stopPoint.y - self.spButton.width/2.0 <= 0) {
                stopPoint = CGPointMake(stopPoint.x, self.spButton.width/2.0);
            }
  
            [UIView animateWithDuration:0.5 animations:^{
                recognizer.view.center = stopPoint;
            }];
        }
            break;
            
        default:
            break;
    }
    
    [recognizer setTranslation:CGPointMake(0, 0) inView:self.view];
}

至此就大功告成啦。里面的一些方法、图片名称，自行替换成你需要的。