iOS
UILabelのテキスト下線

Objective Cを使用してUILabelのテキストに下線を引く

UILabel *label=[[UILabel alloc]initWithFrame:CGRectMake(0, 0, 320, 480)];
label.backgroundColor=[UIColor lightGrayColor];
NSMutableAttributedString *attributedString;
attributedString = [[NSMutableAttributedString alloc] initWithString:@"Apply Underlining"];
[attributedString addAttribute:NSUnderlineStyleAttributeName value:@1 range:NSMakeRange(0, [attributedString length])];
[label setAttributedText:attributedString];

Swiftを使ってUILabelのテキストに下線を引く

 let label = UILabel.init(frame: CGRect(x: 0, y:0, width: 100, height: 40))
 label.backgroundColor = .lightGray
 let attributedString = NSMutableAttributedString.init(string: "Apply UnderLining")
 attributedString.addAttribute(NSUnderlineStyleAttributeName, value: 1, range: NSRange.init(location: 0, length: attributedString.length))
 label.attributedText = attributedString