创建button设置可以折行显示

- (void)viewDidLoad {

    [super viewDidLoad];

    UIButton * button = [[UIButton alloc] initWithFrame:CGRectMake(20, 30, 150, 70)];

    [self.view addSubview:button];

    [button setTitle:@"button" forState:UIControlStateNormal];

    [button setTitleColor:[UIColor blackColor] forState:UIControlStateNormal];

    //button 折行显示设置

    /*

     NSLineBreakByWordWrapping = 0,     	// Wrap at word boundaries, default

     NSLineBreakByCharWrapping,		// Wrap at character boundaries

     NSLineBreakByClipping,		// Simply clip 裁剪从前面到后面显示多余的直接裁剪掉

         文字过长 button宽度不够时: 省略号显示位置...

     NSLineBreakByTruncatingHead,	// Truncate at head of line: "...wxyz" 前面显示

     NSLineBreakByTruncatingTail,	// Truncate at tail of line: "abcd..." 后面显示

     NSLineBreakByTruncatingMiddle	// Truncate middle of line:  "ab...yz" 中间显示省略号

     */

    button.titleLabel.lineBreakMode = NSLineBreakByWordWrapping;

    // you probably want to center it

    button.titleLabel.textAlignment = NSTextAlignmentCenter; // if you want to

    button.layer.borderColor = [UIColor blackColor].CGColor;

    button.layer.borderWidth = 1.0;

    // underline Terms and condidtions

    NSMutableAttributedString* tncString = [[NSMutableAttributedString alloc] initWithString:@"View Terms and Conditions"];

    //设置下划线...

    /*

     NSUnderlineStyleNone                                    = 0x00, 无下划线

     NSUnderlineStyleSingle                                  = 0x01, 单行下划线

     NSUnderlineStyleThick NS_ENUM_AVAILABLE(10_0, 7_0)      = 0x02, 粗的下划线

     NSUnderlineStyleDouble NS_ENUM_AVAILABLE(10_0, 7_0)     = 0x09, 双下划线

     */

    [tncString addAttribute:NSUnderlineStyleAttributeName

                      value:@(NSUnderlineStyleSingle)

                      range:(NSRange){0,[tncString length]}];

    //此时如果设置字体颜色要这样

    [tncString addAttribute:NSForegroundColorAttributeName value:[UIColor blueColor]  range:NSMakeRange(0,[tncString length])];

    //设置下划线颜色...

    [tncString addAttribute:NSUnderlineColorAttributeName value:[UIColor redColor] range:(NSRange){0,[tncString length]}];

    [button setAttributedTitle:tncString forState:UIControlStateNormal];

}

• 设置button的下划线直接设置文字的属性NSMutableAttributedString的tncString添加文字属性NSUnderlineStyleAttributeName并设置下划线样式,NSUnderlineStyleNone -- 无下划线,NSUnderlineStyleSingle -- 单行下划线,NSUnderlineStyleThick -- 单行加粗下划线,NSUnderlineStyleDouble -- 双下划线.
• 设置下划线颜色属性NSUnderlineColorAttributeName
• 最主要的是设置button的标题为NSMutableAttributedString包含多种属性的字符串string.

UILabel下划线设置: http://www.cnblogs.com/adampei-bobo/p/6500782.html