给button增加下划线

如何给button增加下划线简单版

 

- (void)setUnderLineForButton:(UIButton *)btn withTitle:(NSString *)title{

//利用富文本的方式增加button下划线

NSMutableAttributedString *str = [[NSMutableAttributedString alloc]initWithString:title];

NSRange strRange = {0,[str length]};

[str addAttribute:NSUnderlineStyleAttributeName value:[NSNumber numberWithInteger:NSUnderlineStyleSingle] range:strRange];

[btn setAttributedTitle:str forState:UIControlStateNormal];

}