Swift - How to replace characters in a String?

Question

I am looking for a way to replace characters in a Swift String.

In this example String: "This is my string"

I would like to replace the spaces, " ", with "+" to end up with "This+is+my+string".

How can I achieve this?

Answer 1

you can test this:

let newString = test.stringByReplacingOccurrencesOfString(" ", withString: "+", options: nil, range: nil)

Answer 2

Starting from iOS 16 We could use new method on RangeReplaceableCollection replace(_:with:maxReplacements:), that uses Regex as a parameter, where we can customize our request.

var myString = "This is my string"
myString.replace(" ", with: "+")

But don't forget to import RegexBuilder to enable this

Answer 3

Swift 5.5

But this might work in earlier versions.

I'm frequently replacing because I want to replace "any whitespace or -" with a _ or something like that. This extension on string lets me do that.

extension String {
    func removingCharacters(_ characters:CharacterSet) -> Self {
        Self(self.unicodeScalars.filter {
            !characters.contains($0)
        })
    }
    func removingCharacters(in string:String) -> Self {
        Self(self.unicodeScalars.filter {
            !CharacterSet(charactersIn:string).contains($0)
        })
    }
    
    func replacingCharacters(_ characters:CharacterSet, with newChar:Character) -> Self {
        String(self.compactMap( {
            CharacterSet(charactersIn: "\($0.1)").isSubset(of: characters)
             ? newChar : $0.1
        }))
    }
    
    func replacingCharacters(in string:String, with newChar:Character) -> Self {
        String(self.compactMap( {
            CharacterSet(charactersIn: "\($0)").isSubset(of: CharacterSet(charactersIn:string))
             ? newChar : $0
        }))
    }
}

usage:

print("hello \n my name\t is Joe".removingCharacters(.whitespacesAndNewlines))
print("hello \n my name\t is Joe".removingCharacters(in: " \t\n"))

print("ban annan anann ana".replacingCharacters(.whitespacesAndNewlines, with: "_"))
print("ban-annan anann ana".replacingCharacters(in: " -", with: "_"))

Obviously for a single character the .replacingOccurrences(of: " ", with: "+") is better.

I have not done a performance comparison to the

let toArray = aString.components(separatedBy: characterSet)
let backToString = toArray.joined(separator: "+") 

style done in Ramis's extension. I'd be interested if someone does.

See also replacing emoji's: https://stackoverflow.com/a/63416058/5946596

Answer 4

This answer has been updated for Swift 4 & 5. If you're still using Swift 1, 2 or 3 see the revision history.

You have a couple of options. You can do as @jaumard suggested and use replacingOccurrences()

let aString = "This is my string"
let newString = aString.replacingOccurrences(of: " ", with: "+", options: .literal, range: nil)

And as noted by @cprcrack below, the options and range parameters are optional, so if you don't want to specify string comparison options or a range to do the replacement within, you only need the following.

let aString = "This is my string"
let newString = aString.replacingOccurrences(of: " ", with: "+")

Or, if the data is in a specific format like this, where you're just replacing separation characters, you can use components() to break the string into and array, and then you can use the join() function to put them back to together with a specified separator.

let toArray = aString.components(separatedBy: " ")
let backToString = toArray.joined(separator: "+")

Or if you're looking for a more Swifty solution that doesn't utilize API from NSString, you could use this.

let aString = "Some search text"

let replaced = String(aString.map {
    $0 == " " ? "+" : $0
})

Answer 5

Swift 5.5

I am using this extension:

extension String {

    func replaceCharacters(characters: String, toSeparator: String) -> String {
        let characterSet = CharacterSet(charactersIn: characters)
        let components = components(separatedBy: characterSet)
        let result = components.joined(separator: toSeparator)
        return result
    }

    func wipeCharacters(characters: String) -> String {
        return self.replaceCharacters(characters: characters, toSeparator: "")
    }
}

Usage:

"<34353 43434>".replaceCharacters(characters: "< >", toSeparator:"+") // +34353+43434+
"<34353 43434>".wipeCharacters(characters: "< >") // 3435343434

Answer 6

Since Swift 2, String does no longer conform to SequenceType. In other words, you can not iterate through a string with a for...in loop.

The simple and easy way is to convert String to Array to get the benefit of the index just like that:

let input = Array(str)

I remember when I tried to index into String without using any conversion. I was really frustrated that I couldn’t come up with or reach a desired result, and was about to give up. But I ended up creating my own workaround solution, and here is the full code of the extension:

extension String {
    subscript (_ index: Int) -> String {
    
        get {
             String(self[self.index(startIndex, offsetBy: index)])
        }
    
        set {
            remove(at: self.index(self.startIndex, offsetBy: index))
            insert(Character(newValue), at: self.index(self.startIndex, offsetBy: index))
        }
    }
}

Now that you can read and replace a single character from string using its index just like you originally wanted to:

var str = "cat"
for i in 0..<str.count {
 if str[i] == "c" {
   str[i] = "h"
 }
}

print(str)

It’s simple and useful way to use it and get through Swift’s String access model. Now that you’ll feel it’s smooth sailing next time when you can loop through the string just as it is, not casting it into Array.

Try it out, and see if it can help!

Answer 7

var str = "This is my string"

print(str.replacingOccurrences(of: " ", with: "+"))

Output is

This+is+my+string

Answer 8

Less happened to me, I just want to change (a word or character) in the String

So I've use the Dictionary

  extension String{
    func replace(_ dictionary: [String: String]) -> String{
          var result = String()
          var i = -1
          for (of , with): (String, String)in dictionary{
              i += 1
              if i<1{
                  result = self.replacingOccurrences(of: of, with: with)
              }else{
                  result = result.replacingOccurrences(of: of, with: with)
              }
          }
        return result
     }
    }

usage

let mobile = "+1 (800) 444-9999"
let dictionary = ["+": "00", " ": "", "(": "", ")": "", "-": ""]
let mobileResult = mobile.replace(dictionary)
print(mobileResult) // 001800444999

Answer 9

var str = "This is my string"
str = str.replacingOccurrences(of: " ", with: "+")
print(str)

Answer 10

I've implemented this very simple func:

func convap (text : String) -> String {
    return text.stringByReplacingOccurrencesOfString("'", withString: "''")
}

So you can write:

let sqlQuery = "INSERT INTO myTable (Field1, Field2) VALUES ('\(convap(value1))','\(convap(value2)')

Answer 11

Xcode 11 • Swift 5.1

The mutating method of StringProtocol replacingOccurrences can be implemented as follow:

extension RangeReplaceableCollection where Self: StringProtocol {
    mutating func replaceOccurrences<Target: StringProtocol, Replacement: StringProtocol>(of target: Target, with replacement: Replacement, options: String.CompareOptions = [], range searchRange: Range<String.Index>? = nil) {
        self = .init(replacingOccurrences(of: target, with: replacement, options: options, range: searchRange))
    }
}

---

var name = "This is my string"
name.replaceOccurrences(of: " ", with: "+")
print(name) // "This+is+my+string\n"

Answer 12

Swift 3, Swift 4, Swift 5 Solution

let exampleString = "Example string"

//Solution suggested above in Swift 3.0
let stringToArray = exampleString.components(separatedBy: " ")
let stringFromArray = stringToArray.joined(separator: "+")

//Swiftiest solution
let swiftyString = exampleString.replacingOccurrences(of: " ", with: "+")

Answer 13

Here's an extension for an in-place occurrences replace method on String, that doesn't no an unnecessary copy and do everything in place:

extension String {
    mutating func replaceOccurrences<Target: StringProtocol, Replacement: StringProtocol>(of target: Target, with replacement: Replacement, options: String.CompareOptions = [], locale: Locale? = nil) {
        var range: Range<Index>?
        repeat {
            range = self.range(of: target, options: options, range: range.map { self.index($0.lowerBound, offsetBy: replacement.count)..<self.endIndex }, locale: locale)
            if let range = range {
                self.replaceSubrange(range, with: replacement)
            }
        } while range != nil
    }
}

(The method signature also mimics the signature of the built-in String.replacingOccurrences() method)

May be used in the following way:

var string = "this is a string"
string.replaceOccurrences(of: " ", with: "_")
print(string) // "this_is_a_string"

Answer 14

This is easy in swift 4.2. just use replacingOccurrences(of: " ", with: "_") for replace

var myStr = "This is my string"
let replaced = myStr.replacingOccurrences(of: " ", with: "_")
print(replaced)

Answer 15

Swift 4:

let abc = "Hello world"

let result = abc.replacingOccurrences(of: " ", with: "_", 
    options: NSString.CompareOptions.literal, range:nil)

print(result :\(result))

Output:

result : Hello_world

Answer 16

Swift 3 solution based on Ramis' answer:

extension String {
    func withReplacedCharacters(_ characters: String, by separator: String) -> String {
        let characterSet = CharacterSet(charactersIn: characters)
        return components(separatedBy: characterSet).joined(separator: separator)
    }
}

Tried to come up with an appropriate function name according to Swift 3 naming convention.

Answer 17

You can use this:

let s = "This is my string"
let modified = s.replace(" ", withString:"+")    

If you add this extension method anywhere in your code:

extension String
{
    func replace(target: String, withString: String) -> String
    {
       return self.stringByReplacingOccurrencesOfString(target, withString: withString, options: NSStringCompareOptions.LiteralSearch, range: nil)
    }
}

Swift 3:

extension String
{
    func replace(target: String, withString: String) -> String
    {
        return self.replacingOccurrences(of: target, with: withString, options: NSString.CompareOptions.literal, range: nil)
    }
}

Answer 18

A Swift 3 solution along the lines of Sunkas's:

extension String {
    mutating func replace(_ originalString:String, with newString:String) {
        self = self.replacingOccurrences(of: originalString, with: newString)
    }
}

Use:

var string = "foo!"
string.replace("!", with: "?")
print(string)

Output:

foo?

Answer 19

Here is the example for Swift 3:

var stringToReplace = "This my string"
if let range = stringToReplace.range(of: "my") {
   stringToReplace?.replaceSubrange(range, with: "your")
} 

Answer 20

Swift extension:

extension String {

    func stringByReplacing(replaceStrings set: [String], with: String) -> String {
        var stringObject = self
        for string in set {
            stringObject = self.stringByReplacingOccurrencesOfString(string, withString: with)
        }
        return stringObject
    }

}

Go on and use it like let replacedString = yorString.stringByReplacing(replaceStrings: [" ","?","."], with: "+")

The speed of the function is something that i can hardly be proud of, but you can pass an array of String in one pass to make more than one replacement.

Answer 21

I think Regex is the most flexible and solid way:

var str = "This is my string"
let regex = try! NSRegularExpression(pattern: " ", options: [])
let output = regex.stringByReplacingMatchesInString(
    str,
    options: [],
    range: NSRange(location: 0, length: str.characters.count),
    withTemplate: "+"
)
// output: "This+is+my+string"

Answer 22

A category that modifies an existing mutable String:

extension String
{
    mutating func replace(originalString:String, withString newString:String)
    {
        let replacedString = self.stringByReplacingOccurrencesOfString(originalString, withString: newString, options: nil, range: nil)
        self = replacedString
    }
}

Use:

name.replace(" ", withString: "+")

Answer 23

If you don't want to use the Objective-C NSString methods, you can just use split and join:

var string = "This is my string"
string = join("+", split(string, isSeparator: { $0 == " " }))

split(string, isSeparator: { $0 == " " }) returns an array of strings (["This", "is", "my", "string"]).

join joins these elements with a +, resulting in the desired output: "This+is+my+string".

Answer 24

Did you test this :

var test = "This is my string"

let replaced = test.stringByReplacingOccurrencesOfString(" ", withString: "+", options: nil, range: nil)