问题
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?
回答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 :(
回答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
}
回答3:
NSMutableAttributedString *signUpString = [[NSMutableAttributedString alloc] initWithString:@"Not a member yet?Sign Up now"];
[signUpString appendAttributedString:[[NSAttributedString alloc] initWithString:@" "attributes:@{NSUnderlineStyleAttributeName: @(NSUnderlineStyleNone)}]];
[signUpString addAttributes: @{NSForegroundColorAttributeName:UIColorFromRGB(0x43484B),NSUnderlineStyleAttributeName:[NSNumber numberWithInteger:NSUnderlineStyleSingle]} range:NSMakeRange(17,11)];
signUpLbl.attributedText = [signUpString copy];
It worked for me
回答4:
It's September 2018, so this answer is not about iOS8 but it still relates to underlining part of a string.
Here is a Swift 4 extension that underlines a given term within an already composed myAttributedString
extension NSMutableAttributedString {
func underline(term: String) {
guard let underlineRange = string.range(of: term) else {
return
}
let startPosition = string.distance(from: term.startIndex, to: underlineRange.lowerBound)
let nsrange = NSRange(location: startPosition, length: term.count)
addAttribute(
.underlineStyle,
value: NSUnderlineStyle.styleSingle.rawValue,
range: nsrange)
}
}
Usage: myAttributedString.underline(term: "some term")
回答5:
Swift 5 version of @Joss's answer with few modifications, by adding a returned NSMutableAttributedString, because I couldn't use the original solution without it.
extension NSMutableAttributedString {
func underline(term: String) -> NSMutableAttributedString {
guard let underlineRange = string.range(of: term) else {
return NSMutableAttributedString()
}
let startPosition = string.distance(from: term.startIndex, to: underlineRange.lowerBound)
let nsrange = NSRange(location: startPosition, length: term.count)
addAttribute(
.underlineStyle,
value: NSUnderlineStyle.single.rawValue,
range: nsrange)
return self
}
}
Usage:
let myUnderLinedText = "Hello World"
let underLinedMutableString = NSMutableAttributedString(string: myUnderLinedText, attributes: titleAttributes).underline(term: myUnderLinedText)
回答6:
I used the following extension (using exidy's function) in playground/simulator and it worked fine , you may change/add attributes depending on your needs
extension NSMutableAttributedString
{
func changeWordsColour(terms:[NSString])
{
let string = self.string as NSString
self.addAttribute(NSForegroundColorAttributeName, value: UIColor.brownColor(), range: NSMakeRange(0, self.length))
for term in terms
{
let underlineRange = string.rangeOfString(term as String)
self.addAttribute(NSForegroundColorAttributeName, value: UIColor.redColor(), range: underlineRange)
}
}
}
let myStr = NSMutableAttributedString(string: "Change Words Colour")
myStr.changeWordsColour(["change","Colour"])
回答7:
Add color for underline attribute:
[attributedString addAttribute:NSUnderlineColorAttributeName
value:[UIColor redColor]
range:NSMakeRange(5, 6)];
来源：https://stackoverflow.com/questions/26136157/underline-part-of-a-string-using-nsmutableattributedstring-in-ios-8-is-not-worki