想製作一個按鈕，類似於iPhone 的輔助touch的那個小白點的按鈕。但是注意：千萬不能也做成小白點，可能會導致稽核被拒。

不明白網路上查到的那些，為什麼會那麼複雜，涉及到那麼多的頁面。其實只要在要出現這個按鈕的控制器的.m檔案裡寫幾段程式碼就可以解決，非常輕便，尤其適合開發新手。

首先，在想放這個button的vc裡，建立一個成員物件。

@property (nonatomic,strong)UIButton *spButton

然後就可以開始建立按鈕了，我寫成了一個方法：

        //建立可拖動、自動貼近邊緣的 事件上報按鈕
        [self initAddEventBtn];

方法的具體內容：

-(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];
    //新增手勢
    UIPanGestureRecognizer *panRcognize=[[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePanGesture:)];
    [panRcognize setMinimumNumberOfTouches:1];
    [panRcognize setEnabled:YES];
    [panRcognize delaysTouchesEnded];
    [panRcognize cancelsTouchesInView];
    [btn addGestureRecognizer:panRcognize];
}
 

醉關鍵的部分來了，實現按鈕的移動事件處理：

- (void)handlePanGesture:(UIPanGestureRecognizer *)recognizer
{
    //移動狀態
    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);
                    }
                }
            }
            
            //如果按鈕超出螢幕邊緣
            if (stopPoint.y + self.spButton.width+40>= SCREEN_HEIGHT) {
                stopPoint = CGPointMake(stopPoint.x, SCREEN_HEIGHT - self.spButton.width/2.0-49);
                NSLog(@"超出螢幕下方了！！"); //這裡注意iphoneX的適配。。X的SCREEN高度演算法有變化。
            }
            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];
}