How to make an underlined text in UILabel?

问题:

How can I make an underlined text in UILabel?

I had tried by making a UILabel with height 0.5f and place it under the text. This line label is not visible when I am running my app in iPhone 4.3 and iPhone 4.3 simulator, but it is visible in iPhone 5.0 simulator onwards. Why?

How can I do this?

回答1:

Objective-C

iOS 6.0 > version

UILabel supports NSAttributedString

NSMutableAttributedString *attributeString = [[NSMutableAttributedString alloc] initWithString:@"Hello Good Morning"];
[attributeString addAttribute:NSUnderlineStyleAttributeName
                        value:[NSNumber numberWithInt:1]
                        range:(NSRange){0,[attributeString length]}];

Swift

let attributeString: NSMutableAttributedString =  NSMutableAttributedString(string: "Hello Good Morning")
attributeString.addAttribute(NSUnderlineStyleAttributeName, value: 1, range: NSMakeRange(0, attributeString.length))

Definition :

- (void)addAttribute:(NSString *)name value:(id)value range:(NSRange)aRange

Parameters List:

name : A string specifying the attribute name. Attribute keys can be supplied by another framework or can be custom ones you define. For information about where to find the system-supplied attribute keys, see the overview section in NSAttributedString Class Reference.

value : The attribute value associated with name.

aRange : The range of characters to which the specified attribute/value pair applies.

Now use like this:

yourLabel.attributedText = [attributeString copy];

---

iOS 5.1.1 < version

You needs 3 party attributed Label to display attributed text:

1) Refer TTTAttributedLabel link. Its best third party attributed Label to display attributed text.

2) refer OHAttributedLabel for third party attributed Label

回答2:

I am using Xcode 9 and iOS 11. To make the UILabel with an underline beneath it. You can use both 1. Using code 2. Using xib

Using code:

NSMutableAttributedString *attributeString = [[NSMutableAttributedString alloc] initWithString:@"I am iOS Developer"];
[attributeString addAttribute:NSUnderlineStyleAttributeName
                        value:[NSNumber numberWithInt:1]
                        range:(NSRange){0,[attributeString length]}];
lblAttributed.attributedText = attributeString;

Using Xib:

We can also use for button too.

回答3:

The Designer Way - Highly Customisable Version

I personally prefer to customise my design(s) as much as possible. Sometimes, you will find that using the built-in underline tool is not easily customisable.

Here is how I do it:

1 First I create a UIView for the underline. You can then choose your background color, either in IB or programmatically. Constraints are key here.

2 Then, you can customise the underline as much as you like. For example, to adapt the width of the underline for better visual effect, create an outlet connection to a constraint in Interface Builder

3 You can then easily programmatically customise your underline view. For example here, to give you an idea we will make the underline 20 px wider than the title "Breads":

var originalString: String = "Breads"
let myString: NSString = originalString as NSString
let size: CGSize = myString.size(attributes: [NSFontAttributeName: UIFont.systemFont(ofSize: 14.0)])
self.widthUnderlineTitle.constant = size.width + 20

Results:

回答4:

Take a look at TTTAttributedLabel. If you're allowed to use 3d-party components just replace your UILabels with TTTAttributedLabel where you need it (drop-in replacement). Works with iOS < 6.0!

回答5:

Swift extension on UILabel:

Still needs improvement, any thoughts are welcome:

extension UILabel{

    func underLine(){    
        if let textUnwrapped = self.text{
            let underlineAttribute = [NSUnderlineStyleAttributeName: NSUnderlineStyle.StyleSingle.rawValue]
            let underlineAttributedString = NSAttributedString(string: textUnwrapped, attributes: underlineAttribute)
            self.attributedText = underlineAttributedString   
        }   
    }
}

One of the cons i can think of right now is that it will need to be called each time text changes, and there is no actual way of turning it off...

回答6:

Swift 4.0

var attributeString = NSMutableAttributedString(string: "Hello Good Morning")
attributeString.addAttribute(NSUnderlineStyleAttributeName, value: 1, range: NSRange)

回答7:

Swift 5

let attributeString: NSMutableAttributedString =  NSMutableAttributedString(string: yourLabel.text ?? "")
attributeString.addAttribute(NSAttributedString.Key.underlineStyle, value: 1, range: NSMakeRange(0, attributeString.length))
yourLabel.attributedText = attributeString