UILabel UiButton 文字下面加下划线

NSMutableAttributedString *str = [[NSMutableAttributedString alloc] initWithString:@"直接进入"];

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

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

[self.comingBtn setAttributedTitle:str forState:UIControlStateNormal];

//self.comingLabel.attributedText = str;