小编Nic*_*son的帖子

在xcode中,当我打开文本字段的.xib中的十进制键盘键盘选项,并运行应用程序时,收到此错误:

Jun 13 01:22:38 Nicholas-Gibsons-iPhone Quick Utilities[1009] <Error>: 
CGContextSetFillColorWithColor: invalid context 0x0. This is a serious error. This 
application, or a library it uses, is using an invalid context  and is thereby 
contributing to an overall degradation of system stability and reliability. This notice is 
a courtesy: please fix this problem. It will become a fatal error in an upcoming update.

如果您知道这意味着什么,那么您将获得很多帮助!非常感谢!

我有一个滑块,当它开始更改值时,会显示另一个标签(让用户看到他们正在做什么).唯一的问题是我需要知道用户何时完成了滑块的编辑,这样我才能让UILabel再次消失.有没有办法做到这一点？下面的代码显示了滑块值开始变化时的操作.谢谢你的帮助!

- (IBAction)sliderValueChanged:(UISlider *)sender {
    tipPercentLabel.text = [NSString stringWithFormat:@"%.f", ([sender value] * 100)];
    tipPercentLabel2.text = [NSString stringWithFormat:@"%.f", ([sender value] * 100)];

    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:1.0];
    [tipPercentLabel setAlpha:0.3];
    [tipPercentLabel2 setAlpha:1.0];
    [UIView commitAnimations];


    [self performSelector:@selector(autoTipCalc) withObject:nil afterDelay:0.01];
}