Swift String replacingOccurrences()

The replacingOccurrences() method replaces each matching occurrence of the old character/text in the string with the new character/text.


import Foundation
var str1 = "bat ball"

// replace b with c print(str1.replacingOccurrences(of: "b",with: "c"))
// Output: cat call

replacingOccurrences() Syntax

The syntax of the replaceOccurrences() method is:

string.replacingOccurrences(of old: String, with new: String)

Here, string is an object of the String class.

replacingOccurrences() Parameters

The replacingOccurences() method can take two parameters:

  • old - old substring you want to replace
  • new - new substring which will replace the old substring

replacingOccurrences() Return Value

  • returns a copy of the string where the old substring is replaced with the new substring

Note: If the old substring is not found, it returns the copy of the original string.

Example 1: Swift String replacingOccurrences()

import Foundation 

var text = "Java is awesome. Java is fun."

// all occurrences of "Java" is replaced with "Swift" var new = text.replacingOccurrences(of:"Java", with: "Swift")
// "Python" is not the substring of text , so returns original string var new1 = text.replacingOccurrences(of:"Python", with: "Swift")


Swift is awesome. Swift is fun.
Java is awesome. Java is fun.

In this program, text.replacingOccurrences(of:"Python", with: "Swift") returns a copy of the original string since "Python" is not a substring of text.

Example 2: Use of replacingOccurrences() with Characters

import Foundation 

var str1 = "abc cba"

// all occurrences of 'a' is replaced with 'z'
print(str1.replacingOccurrences(of: "a", with: "z"))  // zbc cbz

// all occurences of 'L' is replaced with 'J'
print("Lwift".replacingOccurrences(of: "L", with: "S")) // Swift

// "4" not in the string, so returns original string print("Hello".replacingOccurrences(of: "4", with:"J")) // Hello


Swift is awesome. Swift is fun.
Java is awesome. Java is fun.

In this program, we have used the replacingOccurences() function with:

  • str1 - a string variable
  • "Lwift" and "Hello" - string literals
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