Replace only the first instance of a substring in an NSString

Question

So if you have an NSString that goes:

@"My blue car is bigger than my blue shoes or my blue bicycle"; 

I would like a method that replaces only the first instance of blue with green, to produce:

@"My green car is bigger than my blue shoes or my blue bicycle"; 

How does one do this?

Answer 1

Assuming the following inputs:

NSString *myString = @"My blue car is bigger then my blue shoes or my blue bicycle"; NSString *original = @"blue"; NSString *replacement = @"green"; 

The algorithm is quite simple:

NSRange rOriginal = [myString rangeOfString:original];  if (NSNotFound != rOriginal.location) {     myString = [myString stringByReplacingCharactersInRange:rOriginal withString:replacement]; } 

Answer 2

SWIFT 3 and 4 UPDATE:

extension String  {     func stringByReplacingFirstOccurrenceOfString(             target: String, withString replaceString: String) -> String     {         if let range = self.range(of: target) {             return self.replacingCharacters(in: range, with: replaceString)         }         return self     }  }