Replace only the first instance of a substring in an NSString - iphone

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
}
}

Answer 3

A more Swift'y version of the implementations posted here. This one matches the syntax replacingOccurrences(of:with:) in Swift 5.1
extension String {
func replacingFirstOccurrence(of target: String, with replacement: String) -> String {
guard let range = self.range(of: target) else { return self }
return self.replacingCharacters(in: range, with: replacement)
}
}
An example of usage:
let string = "I like bacon, please give me some more bacon!"
let newString = string.replacingFirstOccurrence(of: "bacon", with: "meat")

Answer 4

Swift 4 version:
func replacingFirstOccurrence(of string: String, with replacement: String) -> String {
guard let range = self.range(of: string) else { return self }
return replacingCharacters(in: range, with: replacement)
}

Answer 5

In Swift is useful extends String in this way:
public extension String {
func stringByReplacingFirstOccurrenceOfString(target: String, withString replaceString: String) -> String {
if let range = self.rangeOfString(target) {
return self.stringByReplacingCharactersInRange(range, withString: replaceString)
}
return self
}
}
In this way you can call wherever:
let s = "The red red cat".stringByReplacingFirstOccurrenceOfString("red", withString: "fat")
print(s) // "The fat red cat"

Answer 6

NSString *initialString = #"My blue car is bigger then my blue shoes or my blue bicycle";
NSRange range = [initialString rangeOfString:#"blue"];
NSString *replacedString = [initialString stringByReplacingCharactersInRange:range withString:#"green"];
NSLog(#"replacedString: %#", replacedString);

Answer 7

First locate the substring, and then make the replacement. Example :
NSString *aString = #"foo bar foo";
NSRange firstFooRange = [aString rangeOfString:#"foo"];
NSString *anotherString = [aString stringByReplacingOccurrencesOfString:#"foo"
withString:#"bar"
options:0
range:firstFooRange];
NSString documentation.

Answer 8

-(NSString*) replaceFirstOccuarnceFromString: (NSString*)input withOriginal:(NSString*) original AndReplacment:(NSString*)replacement
{
NSRange rOriginal = [input rangeOfString: original];
if (NSNotFound != rOriginal.location) {
input = [input
stringByReplacingCharactersInRange: rOriginal
withString: replacement];
}
return input;
}