Underline part of a string using NSMutableAttributedString in iOS 8 is not working

Question

I try to underline part of a string, for example, a 'string' part in 'test string' string. I'm using NSMutableAttributedString and my solution was working well on iOS7.

NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc]         initWithString:@"test string"]; [attributedString addAttribute:NSUnderlineStyleAttributeName                          value:@(NSUnderlineStyleSingle)                          range:NSMakeRange(5, 6)]; myLabel.attributedText = attributedString; 

The problem is that my solution is not working in iOS8 anymore. After spending an hour on testing multiple variants of NSMutableAttributedString, I found out that this solution works only when range starts with 0 (length can differ). What is the reason for that? How can I workaround this?

Answer 1

Update: By investigating this question: Displaying NSMutableAttributedString on iOS 8 I finally found the solution!

You should add NSUnderlineStyleNone at the beginning of the string.

Swift 4.2 (none was removed):

let attributedString = NSMutableAttributedString() attributedString.append(NSAttributedString(string: "test ",                                            attributes: [.underlineStyle: 0])) attributedString.append(NSAttributedString(string: "s",                                            attributes: [.underlineStyle: NSUnderlineStyle.single.rawValue])) attributedString.append(NSAttributedString(string: "tring",                                            attributes: [.underlineStyle: 0])) 

Objective-C:

 NSMutableAttributedString *attributedString = [[NSMutableAttributedString alloc] init];  [attributedString appendAttributedString:[[NSAttributedString alloc] initWithString:@"test "                                                                           attributes:@{NSUnderlineStyleAttributeName: @(NSUnderlineStyleNone)}]];  [attributedString appendAttributedString:[[NSAttributedString alloc] initWithString:@"s"                                                                          attributes:@{NSUnderlineStyleAttributeName: @(NSUnderlineStyleSingle),                                                                                       NSBackgroundColorAttributeName: [UIColor clearColor]}]];  [attributedString appendAttributedString:[[NSAttributedString alloc] initWithString:@"tring"]]; 

Another bonus of such approach is absence of any ranges. Very nice for localized strings.

Seems like it is Apple bug :(

Answer 2

I found that if you apply UnderlineStyleNone to the whole string you can then selectively apply underline to a part that starts in the middle:

func underlinedString(string: NSString, term: NSString) -> NSAttributedString {     let output = NSMutableAttributedString(string: string)     let underlineRange = string.rangeOfString(term)     output.addAttribute(NSUnderlineStyleAttributeName, value: NSUnderlineStyle.StyleNone.rawValue, range: NSMakeRange(0, string.length))     output.addAttribute(NSUnderlineStyleAttributeName, value: NSUnderlineStyle.StyleSingle.rawValue, range: underlineRange)      return output }