Button的标题文字添加下划线

1 NSMutableAttributedString *c = [[NSMutableAttributedString alloc] initWithString:@"忘记密码?"];
2     NSRange contentRange = {0, [c length]};
3     [c addAttribute:NSUnderlineStyleAttributeName value:[NSNumber numberWithInteger:NSUnderlineStyleSingle] range:contentRange];
4     //UIFontTools * fonttools = [UIFontTools defaultUIFontTool];
5     //[self.btn_wangjimima.titleLabel setFont:[fonttools forgetPWDButtonFont]];
6   self.btn_skipVerification.titleLabel.attributedText = c;