iPhone开发 多点触控的问题

虽然这个问题很简单，但是对于我这接触两天的菜鸟来说也弄了很久，网上又找不到相关的解决方法，避免其他人和我一样，还是记录一下

一般网上找到的教程是这么教：

-(void )touchesBegin:(NSSet *)touches withEvent:(UIEvent *)event

{   
    
    NSArray *twoTouches = [touches allObjects];
    UITouch *firstTouch = [twoTouches objectAtIndex:0];
    UITouch *secondTouch = [twoTouches objectAtIndex:1];
    CGPoint point1 =[touch1 locationInView:[touch1 view]];
    CGPoint point2 =[touch2 locationInView:[touch2 view]];

    NSLog(@"point1:%@",NSStringFromCGPoint(point1));
    NSLog(@"point2:%@",NSStringFromCGPoint(point2));
}

但是这里面首先NSArray这个累不知道能不能去NSSet这个类的东西

接着最主要的问题是touchesBegin这个方法在你第一只手指触碰就立即触发这方法。

所以你想去两个手指的话这肯定不行，虽然编译器不会报错，但是一碰就死机

其实只要改个方法就行，用touchesMoved

-(void )touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    NSSet *allTouches = [event allTouches];
    if(allTouches.count ==2)
    {
    UITouch *touch1 = [[allTouches allObjects] objectAtIndex:0];
    UITouch *touch2 = [[allTouches allObjects] objectAtIndex:1];
    
    CGPoint point1 =[touch1 locationInView:[touch1 view]];
    CGPoint point2 =[touch2 locationInView:[touch2 view]];

    NSLog(@"point1:%@",NSStringFromCGPoint(point1));
    NSLog(@"point2:%@",NSStringFromCGPoint(point2));
    }

}

哈哈，在这里谢谢@彭博的指点～