iphone开发-UIView Touch事件

怎样捕获手指的触摸事件呢？

理论不说了，在开发文档里面说的很详细。就说说实现。

其实就是要重写实现三个函数，如下：

touch开始时会调用touchesBegan

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    NSSet *allTouches = [event allTouches];
    UITouch *touch = [touches anyObject];

    NSLog(@"touch view++++++%@", [touch view]);

   // [touch view]获得当前touch的view

   //[allTouches count]获得当前touch的是否是多触摸，如果 [allTouches count] == 1就不是多触摸。

 switch ([allTouches count]) {
        case 1: {
            // potential pan gesture
            UITouch *touch = [[allTouches allObjects] objectAtIndex:0];
            [self setPanningModeWithLocation:[touch locationInView:self]];
        } break;
            
        case 2: {
            // potential zoom gesture
            UITouch *touch0 = [[allTouches allObjects] objectAtIndex:0];
            UITouch *touch1 = [[allTouches allObjects] objectAtIndex:1];
            CGFloat spacing = 
            [self eucledianDistanceFromPoint:[touch0 locationInView:self] 
                                     toPoint:[touch1 locationInView:self]];
            [self setZoomingModeWithSpacing:spacing];
        } break;

      default:
            [self resetTouches];
            break;

        }
    }

 

//是指触摸移动时，调touchesMoved

#define ZOOM_IN_TOUCH_SPACING_RATIO       (0.75)
#define ZOOM_OUT_TOUCH_SPACING_RATIO      (1.5)

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{

      //获取当前touch的点
      CGPoint location = [touch locationInView:self];

switch ([allTouches count])
    {
        case 1: 
        {
        }
        break;
        case 2: 
        {
            UITouch *touch0 = [[allTouches allObjects] objectAtIndex:0];
            UITouch *touch1 = [[allTouches allObjects] objectAtIndex:1];
            CGFloat spacing = 
            [self eucledianDistanceFromPoint:[touch0 locationInView:self] 
                                     toPoint:[touch1 locationInView:self]];
            CGFloat spacingRatio = spacing / lastTouchSpacing_;
            
            if (spacingRatio >= ZOOM_OUT_TOUCH_SPACING_RATIO){
            [self zoomIn]; 

           }
            else if (spacingRatio <= ZOOM_IN_TOUCH_SPACING_RATIO) {
             [self zoomOut];
            }
        }
        break;
        default:
              break;
    }

}

 

//结束时调用touchesEnded

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
}

实现这三个方法，根据需要添加相应的代码，完成想要的功能。