案例：根据多点触控用图片来绘制路径 和 清除路径。

主要获取坐标 设置imageview的坐标。

视图默认不支持 多点触控：设置为支持多点触控：[self.view  setMultipleTouchEnabled:YES];

1.循环创建imageView

4 - (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event 5 { 6     NSInteger i = 0; 7     for (UITouch *touch in touches) { 8         UIImageView *imageview = [[UIImageView alloc]initWithImage:self.imageData[i]]; 9         CGPoint location = [touch locationInView:self.view];10         [imageview setCenter:location];11         [self.view addSubview:imageview];12         i++;13     }14 }

 

2.清除self.view

isKindOfClass：  来判断是什么类型的控件。

1         [imageview setCenter:location]; 2         [self.view addSubview:imageview]; 3         i++; 4     } 5 } 6  7 - (void)clearView 8 { 9     for (UIImageView *imageView in self.view.subviews) {10         11         if ([imageView isKindOfClass:[UIImageView class]]) {12             [UIView animateWithDuration:5.0f animations:^{13                 [imageView setAlpha:0.1f];14             } completion:^(BOOL finished) {15                 [imageView removeFromSuperview];16             }] ;17         }18     }19 }