UILabel * fabLab = [[UILabel alloc]initWithFrame:CGRectMake(50, 140, 200, 30)];

    NSMutableAttributedString * aText = [[NSMutableAttributedString alloc] initWithString:@"这是一个很好的东西"];

    [aText addAttribute:NSForegroundColorAttributeName value:[UIColor redColor] range:NSMakeRange(4, 2)];

// NSMakeRange(从第几个字开始 ， 颜色变换的有几个字)

    fabLab.attributedText = aText;

    fabLab.font = [UIFont systemFontOfSize:14.0f];

    [self.view addSubview:fabLab];

label 字体变粗

    fabLab.font = [UIFont fontWithName:@"Helvetica-BoldOblique" size:17];

字体渐变