/*
  定義屬性
 */
@interface ViewController ()
{
  CGPoint _startPoint; //開始點擊的點
  CGPoint _endPoint; //結束點擊的點
  
  UILabel *_label1; //顯示當前觸摸的狀態的標簽
  UILabel *_label2;
  UILabel *_label3;
  UILabel *_label4;
  UIImageView *_imageView; //笑臉圖片
}

/*
  觸摸事件UITouch的系列方法如下所示 <一>到<四>
 */

#pragma mark <一> 當一個或多個手指觸碰屏幕時，發送touchesBegan:withEvent:消息
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
  _label1.text = @"觸摸 開始 ";
  
  //1. 首先獲取觸摸屏幕的手指
  UITouch * touch = [touches anyObject];
  
  //2. 點擊的當前點的坐標
  CGPoint point = [touch locationInView:self.view];
  _label2.text = [NSString stringWithFormat:@"當前點得坐標:x=%.1f, y=%.1f",point.x,point.y];
  
  //4. 獲取觸摸屏幕的次數
  int tapCount = touch.tapCount;
  //5. 獲取觸摸屏幕的手指根數
  int fingerCount = touches.count;
  
  _label3.text = [NSString stringWithFormat:@"觸摸屏幕次數為%i, 觸摸的手指數為%i",tapCount,fingerCount];
  
  //6. 當前視圖默認只支持單點觸摸 如果想添加多點觸摸 必須開啟多點觸摸模式
  self.view.multipleTouchEnabled = YES;
  
  //7.1. 得到開始點擊的點,得到最后點擊的點，計算一下，看看做了什么操作
  _startPoint = [touch locationInView:self.view];
  _label4.text = @"";
}

#pragma mark <二> 當一個或多個手指在屏幕上移動時，發送touchesMoved:withEvent:消息
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
  _label1.text = @"觸摸 move...";
  CGPoint point = [[touches anyObject] locationInView:self.view];
  _label2.text = [NSString stringWithFormat:@"當前點得坐標:x=%.1f, y=%.1f",point.x,point.y];
}

#pragma mark <三> 當一個或多個手指離開屏幕時，發送touchesEnded:withEvent:消息
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
  _label1.text = @"觸摸 結束";
  CGPoint point = [[touches anyObject] locationInView:self.view];
  
  //3. 判斷是否進入了圖片范圍內
  if (CGRectContainsPoint(_imageView.frame, point)) {
    _label2.text = @"停留在笑臉圖片范圍內";
  }
  else
  {
    _label2.text = @"停留在笑臉圖片外面";
  }
  
  //7.2 計算開始到結束偏移量
  float distanceX = fabsf(point.x - _startPoint.x);
  //獲取手指縱向移動的偏移量
  float distanceY = fabsf(point.y - _startPoint.y);
  
  _label4.text = [NSString stringWithFormat:@"x偏移了%.1f，y方向偏移了%.1f",distanceX,distanceY];
  
  _startPoint = CGPointZero;
}

#pragma mark <四> 當觸摸序列被諸如電話呼入這樣的系統事件打斷所意外取消時，發送touchesCancelled:withEvent:消息-(void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
{
  _label1.text = @"觸摸 取消";
}