iOS学习-创建带下划线的button

     UIButton *tempBtn = [UIButton buttonWithType: UIButtonTypeCustom];
     tempBtn.frame = CGRectMake(, , , );

     NSMutableAttributedString *str = [[NSMutableAttributedString alloc] initWithString:@"忘记密码"];
     NSRange strRange = {,[str length]};
     [str addAttribute:NSUnderlineStyleAttributeName value:[NSNumber numberWithInteger:NSUnderlineStyleSingle] range:strRange];
     [tempBtn setAttributedTitle:str forState:UIControlStateNormal];

     tempBtn.titleLabel.textColor = [UIColor blueColor];
     [self.view addSubview: tempBtn];