C TouchesBegan的问题

Question

-(void)ccTouchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
    CGPoint point1 = [touch previousLocationInView:[touch view]];
    CGPoint point2 = [touch locationInView:[touch view]];

    point1 = [[CCDirector sharedDirector]convertToGL:point1];
    point2 = [[CCDirector sharedDirector]convertToGL:point2];


    pre = point1;
    curr = point2;
    CCLOG(@"the pre location is %@",NSStringFromCGPoint(pre));
    CCLOG(@"the curr location is %@",NSStringFromCGPoint(curr));


}

上面的代码有什么问题？ pre和curr变量gve相同的输出？

Answer 1

当触摸开始时，由于触摸刚刚开始，显然没有先前的触摸。所以previousLocation和location都是一样的。

如果您在ccTouchesMoved中运行此代码，它将按预期工作。

Answer 2

您只需要在ccTouchesEnded方法中打印当前位置。它会给你两点之间的差异。

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

所以你必须在ccTouchesBegan方法中获得previousLoaction。