小编Nik*_*kie的帖子

我不清楚MemberOfClass是如何工作的.请查看以下示例.为什么在下面的例子中lbl.textColor不是成员？请为我清楚这一点.

    UILabel *lbl = [[UILabel alloc]initWithFrame:CGRectMake(0, 0, 200, 100)];
    lbl.text = @"HI";
    lbl.textColor = [UIColor grayColor];
    [self.view addSubview:lbl];

    if ([lbl.textColor isMemberOfClass:[UIColor class]]) { // Why Not Memeber
        NSLog(@"Member");
    }else {
        NSLog(@"Not Member");
    }

    if ([lbl.text isMemberOfClass:[NSString class]]) {// Why Not Memeber
        NSLog(@"Member");
    }else {
        NSLog(@"Not Member");
    }
    if ([imgView.image isMemberOfClass:[UIImage class]]) {// Memeber
        NSLog(@"Member");
    }else {
        NSLog(@"Not Member");
    }

//输出

 2014-12-19 20:17:43.383 Demo[13720:70b] Not Member
 2014-12-19 20:17:45.883 Demo[13720:70b] Not Member
 2014-12-19 20:17:52.772 Demo[13720:70b] Member

我正在使用XCode版本4.6(4H127),我在main.m中随机崩溃

请参阅随附的屏幕截图

谢谢

调试器: