iphone - 记录触摸的持续时间，然后打印

Question

如何记录触摸的持续时间并在屏幕上打印出来？

上面的代码是这样的:

// add this ivar to your view controller
NSTimeInterval lastTouch;
int textTime;

// assign the time interval in touchesBegan:
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event;
{
    lastTouch = [event timestamp];
}


// calculate and print interval in touchesEnded:
-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event;
{
    NSTimeInterval touchBeginEndInterval = [event timestamp] - lastTouch;
    textTime = touchBeginEndInterval;
    NSLog(@"touchBeginEndInterval %f", touchBeginEndInterval);
    dynLabel.text = textTime;
}

Answer 1

dynLabel.text = textTime;

标签的 text 属性需要一个 NSString*，但你给它一个 NSTimeInterval 即一个号码。这就是错误的含义。使用例如创建一个字符串NSString 的 -stringWithFormat: 方法。