iphone - 记录一个触摸的持续时间，然后打印出来

Question

您如何记录触摸的持续时间并在屏幕上打印？

这是上面的代码：

// 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 a NSString*，但你给它一个NSTimeIntervalIe 一个数字。这就是错误的意思。-stringWithFormat:使用例如NSString 的方法创建一个字符串。