1. 将UILabel控件的Text属性设为Attributed
2. 在viewDidLoad方法中添加如下语句：
NSDictionary *underlineAttribute = @{NSUnderlineStyleAttributeName: @(NSUnderlineStyleSingle)}; lbPrivacy.attributedText = [[NSAttributedString alloc] initWithString:@"隐私政策" attributes:underlineAttribute];
Done.
原文：http://www.cnblogs.com/ilovewindy/p/4046439.html