一个UILabel上显示不同的字体、颜色

NSMutableAttributedString *str = [[NSMutableAttributedString alloc] initWithString:@"hello world hello world"];
    [str addAttribute:NSFontAttributeName
                value:[UIFont boldSystemFontOfSize:20]
                range:NSMakeRange(6, 5)];
    [str addAttribute:NSBackgroundColorAttributeName
                value:[UIColor greenColor]
                range:NSMakeRange(6, 5)];
    [str addAttributes:@{NSForegroundColorAttributeName:[UIColor redColor],
                         NSFontAttributeName:[UIFont boldSystemFontOfSize:26],
                         NSBackgroundColorAttributeName:[UIColor lightGrayColor]}
                 range:NSMakeRange(12, 5)];
    label.attributedText = str;