How do I convert an NSString from CamelCase to TitleCase, 'playerName' into 'Player Name'?

问题

I'm looking for the easiest way to convert a string from camelback format to Title Case format.

How do I change 'playerName' into 'Player Name'?

回答1:

NSString *str = @"playerName";
NSMutableString *str2 = [NSMutableString string];

for (NSInteger i=0; i<str.length; i++){
    NSString *ch = [str substringWithRange:NSMakeRange(i, 1)];
    if ([ch rangeOfCharacterFromSet:[NSCharacterSet uppercaseLetterCharacterSet]].location != NSNotFound) {
        [str2 appendString:@" "];
    }
    [str2 appendString:ch];
}
NSLog(@"%@", str2.capitalizedString);

回答2:

Here's a simpler Swift version. I've chucked it into an extension

extension String {

    func stringFromCamelCase() -> String {
        var string = self
        string = string.stringByReplacingOccurrencesOfString("([a-z])([A-Z])", withString: "$1 $2", options: NSStringCompareOptions.RegularExpressionSearch, range: Range<String.Index>(start: string.startIndex, end: string.endIndex))
        string.replaceRange(startIndex...startIndex, with: String(self[startIndex]).capitalizedString)
        return string
    }

}

Usage:

var str = "helloWorld"
str = str.stringFromCamelCase()

回答3:

Try using a regex replace

NSString *modified = [input stringByReplacingOccurrencesOfString:@"([a-z])([A-Z])"
                                                      withString:@"$1 $2"
                                                         options:NSRegularExpressionSearch
                                                           range:NSMakeRange(0, input.length)];

回答4:

A little shorter, using NSCharacterSet:

__block NSString *str = @"myVerySpecialPlayerName" ;

// split at uppercase letters
NSArray *splitString = [str componentsSeparatedByCharactersInSet:
     [NSCharacterSet uppercaseLetterCharacterSet]] ;

// get the uppercase letters
NSArray *upperCaseLetters = [str componentsSeparatedByCharactersInSet:
     [[NSCharacterSet uppercaseLetterCharacterSet] invertedSet]] ;

// join with two spaces
str = [splitString componentsJoinedByString:@"  "] ;
__block NSInteger offset = 0 ;

// replace each second space with the missing uppercase letter
[upperCaseLetters enumerateObjectsUsingBlock:^(NSString *character, NSUInteger idx, BOOL *stop) {
    if( [character length] > 0 ) {
        str = [str stringByReplacingCharactersInRange:NSMakeRange(idx+offset+1, 1) withString:character] ;
        offset += 2 ;
    }
}] ;

// & capitalize the first one
str = [str capitalizedString] ;

NSLog(@"%@", str) ; // "My Very Special Player Name"

回答5:

I think you can tackle this problem with some Regular Expressions. Check out this similar question: iPhone dev: Replace uppercase characters in NSString with space and downcase

回答6:

Although a little long, but this category for NSString should do the trick. It passed all my tests:

- (NSString *)splitOnCapital
{
  // Make a index of uppercase characters
  NSRange upcaseRange = NSMakeRange('A', 26);
  NSIndexSet *upcaseSet = [NSIndexSet indexSetWithIndexesInRange:upcaseRange];

  // Split our camecase word
  NSMutableString *result = [NSMutableString string];
  NSMutableString *oneWord = [NSMutableString string];
  for (int i = 0; i < self.length; i++) {
    char oneChar = [self characterAtIndex:i];
    if ([upcaseSet containsIndex:oneChar]) {
      // Found a uppercase char, now save previous word
      if (result.length == 0) {
        // First word, no space in beginning
        [result appendFormat:@"%@", [oneWord capitalizedString]];
      }else {
        [result appendFormat:@" %@", oneWord];
      }

      // Clear previous word for new word
      oneWord = [NSMutableString string];
    }

    [oneWord appendFormat:@"%c", oneChar];
  }

  // Add last word
  if (oneWord.length > 0) {
    [result appendFormat:@" %@", oneWord];
  }

  return result;
}

回答7:

I had a similar issue, the answers here helped me create a solution. I had an array that had a list of labels I wanted to display within a UITableView, one label per row.

My issue was I parsed these labels out of an XML returned by a SOAP action and I had not idea over the format of the strings.

Firstly I implemented webstersx answer into a method. This was great but some of these labels began with a capital letter and some where camel case (e.g. some strings where exampleLabel and others where ExampleLabel. So this meant the ones beginning with a capital had a space inserted in front of the string.

I overcame this by trimming whitespaces from the beggining and end of the string using NSString's stringByTrimmingCharactersInSet.

The next issue was any abbreviations used, such as "ID" or "PNR Status", where being displayed as "I D" and "P N R Status" as the capital letters where, and quite rightly, being picked up and a space inserted before it.

I overcame this issue by implementing a regex similar to emdog4's answer into my new method.

Here is my completed solution:

- (NSString *)formatLabel:(NSString *)label
{
    NSMutableString *str2 = [NSMutableString string];

    for (NSInteger i=0; i<label.length; i++){
        NSString *ch = [label substringWithRange:NSMakeRange(i, 1)];
        if ([ch rangeOfCharacterFromSet:[NSCharacterSet uppercaseLetterCharacterSet]].location != NSNotFound) {
            [str2 appendString:@" "];
        }
        [str2 appendString:ch];
    }
    NSString * formattedString = [str2 stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]].capitalizedString;

    formattedString = [formattedString stringByReplacingOccurrencesOfString:@"([A-Z]) (?![A-Z][a-z])" withString:@"$1" options:NSRegularExpressionSearch range:NSMakeRange(0, formattedString.length)];

    return formattedString;
}

I then simply call something like this, for example, that will return my nicely formatted string:

NSString * formattedLabel = [self formatLabel:@"PNRStatus"];
NSLog(@"Formatted Label: %@", formattedLabel);

Will output:

2013-10-10 10:44:39.888 Test Project[28296:a0b] Formatted Label: PNR Status

回答8:

If anyone needs a Swift version:

func camelCaseToTitleCase(s: NSString) -> String {
    var newString = ""
    if s.length > 0 {
        newString = s.substringToIndex(1).uppercaseString
        for i in 1..<s.length {
            let char = s.characterAtIndex(i)
            if NSCharacterSet.uppercaseLetterCharacterSet().characterIsMember(char) {
                newString += " "
            }
            newString += s.substringWithRange(NSRange(location: i, length: 1))
        }
    }
    return newString
}

回答9:

Trying to be more unicode compliant

extension String {
    func camelCaseToTitleCase() -> String {
        return unicodeScalars.map(replaceCaptialsWithSpacePlusCapital).joined().capitalized
    }
    private func replaceCaptialsWithSpacePlusCapital(unichar: UnicodeScalar) -> String {
        if CharacterSet.uppercaseLetters.contains(unichar) {
            return " \(unichar)"
        }
        return "\(unichar)"
    }
}

回答10:

while technically shorter, more ineffecient

NSString *challengeString = @"playerName";
NSMutableString *rStr = [NSMutableString stringWithString:challengeString];

while ([rStr rangeOfCharacterFromSet:[NSCharacterSet uppercaseLetterCharacterSet]].location != NSNotFound) {
    [rStr replaceCharactersInRange:[rStr rangeOfCharacterFromSet:[NSCharacterSet uppercaseLetterCharacterSet]] withString:[[NSString stringWithFormat:@" %@", [rStr substringWithRange:[rStr rangeOfCharacterFromSet:[NSCharacterSet uppercaseLetterCharacterSet]]]] lowercaseString]];
}

NSLog(@"%@", rStr.capitalizedString);

回答11:

Not sure this is much shorter than websterx, but I find using characterIsMember easier to read and understand. Also added a length check to fix the space before if the string starts with a capital.

NSString *str = @"PlayerNameHowAboutALongerString";
NSMutableString *str2 = [NSMutableString string];

for (NSInteger i=0; i<str.length; i++){
    unichar ch = [str characterAtIndex:i];
    if ( [[NSCharacterSet uppercaseLetterCharacterSet] characterIsMember:ch]) {
        if (str2.length > 0 ) {
            [str2 appendString:@" "];
        }
    }
    [str2 appendString:[NSString stringWithCharacters:&ch length:1]];
}
NSLog(@"--%@--", str2.capitalizedString);

回答12:

The accepted answer didn't work for me because it doesn't capitalize the first letter, and if the first letter is already capitalized, it adds an extraneous space at the beginning. Here is my improved version:

- (NSString *)titleFromCamelCaseString:(NSString *)input
{
    NSMutableString *output = [NSMutableString string];
    [output appendString:[[input substringToIndex:1] uppercaseString]];
    for (NSUInteger i = 1; i < [input length]; i++)
    {
        unichar character = [input characterAtIndex:i];
        if ([[NSCharacterSet uppercaseLetterCharacterSet] characterIsMember:character])
        {
            [output appendString:@" "];
        }
        [output appendFormat:@"%C", character];
    }
    return output;
}

回答13:

Here is Swift Code (objective c code by webstersx), Thanks !

var str: NSMutableString = "iLoveSwiftCode"

        var str2: NSMutableString = NSMutableString()

        for var i:NSInteger = 0 ; i < str.length ; i++ {

            var ch:NSString = str.substringWithRange(NSMakeRange(i, 1))
            if(ch .rangeOfCharacterFromSet(NSCharacterSet.uppercaseLetterCharacterSet()).location != NSNotFound) {
            str2 .appendString(" ")
            }
            str2 .appendString(ch)
        }
        println("\(str2.capitalizedString)")

    }

回答14:

NSString *input = @"playerName";
NSString *modified = [input stringByReplacingOccurrencesOfString:@"(?<!^)[A-Z]" withString:@" $0" options:NSRegularExpressionSearch range:NSMakeRange(0, input.length)].capitalizedString;

回答15:

Another solution under Swift 2.2

extension String {
    var stringFromCamelCase:String {
        return (self as NSString).replacingOccurrences(
            of: "([a-z])([A-Z])",
            with: "$1 $2",
            options: CompareOptions.regularExpressionSearch,
            range: NSMakeRange(0, self.characters.count)
            ).uppercaseFirst
    }

    var uppercaseFirst: String {
        return String(characters.prefix(1)).uppercased() + String(characters.dropFirst()).lowercased()
    }
}