iOS给label添加下划线

    UILabel *myLabel = [[UILabel alloc] initWithFrame:CGRectMake(100, 100, 320, 40)];

    NSMutableAttributedString *content = [[NSMutableAttributedString alloc] initWithString:@"initWithFrame"];

    NSRange contentRange = {0, [content length]};

    [content addAttribute:NSUnderlineStyleAttributeName value:[NSNumber numberWithInteger:NSUnderlineStyleSingle] range:contentRange];

    

    myLabel.attributedText = content;

    [self.view addSubview:myLabel];