How to remove all chars except those in CharacterSet in Swift

Question

I am trying to trim a phone number and using the following code but it does not trim whitespace or the '-'. I need to erase all chars except those in the character set given

 func trimmedNumber(s : String)->String
 {
    let characterSet = NSCharacterSet(charactersInString: "+*#0123456789")
   let trimmedString =  s.stringByTrimmingCharactersInSet(characterSet.invertedSet)
    return trimmedString
}

Your code does exactly what you want. I tried in a Playground and it's removing whitespace and "-". ([screenshot](https://www.evernote.com/shard/s236/sh/298dec5a-a493-4501-8a09-1092a6490b88/9db22252948663c5/res/ce293b62-a398-4bbf-93e1-9a934a2a2733/skitch.png)) — Eric Aya, Aug 28 '15 at 11:22
@EricD. try it on string "5467-rf34". This code doesn't work. — egor.zhdan, Aug 28 '15 at 11:23
@egor.zhdan Actually this is expected: the [documentation](https://developer.apple.com/library/mac/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/#//apple_ref/occ/instm/NSString/stringByTrimmingCharactersInSet:) says stringByTrimmingCharactersInSet "Returns a new string made by removing from *both ends* of the receiver characters contained in a given character set." — Eric Aya, Aug 28 '15 at 11:31
@EricD. yes, I understand, but don't know how to remove characters not only from ends of the string. — egor.zhdan, Aug 28 '15 at 11:35

dalton_c · Answer 1 · 2018-04-11T16:24:50.277

36

Swift 3/4:

let set = CharacterSet(charactersIn: "+*#0123456789")
let stripped = s.components(separatedBy: set.inverted).joined()

edited Apr 11 '18 at 16:24

answered Jul 31 '17 at 00:40

dalton_c

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i am not able to delete characters from my textfield – Skywalker Jun 25 '21 at 09:06

oisdk · Accepted Answer · 2015-08-28T14:30:54.167

9

func trimmedNumber(s : String) -> String {
  let characterSet = Set("+*#0123456789".characters)
  return String(s.characters.lazy.filter(characterSet.contains))
}

Or in Swift 1:

func trimmedNumber(s : String) -> String {
  let characterSet = Set("+*#0123456789")
  return String(lazy(s).filter { characterSet.contains($0) })
}

edited Aug 28 '15 at 14:30

answered Aug 28 '15 at 11:33

oisdk

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1

Does using `lazy` above save memory? – ma11hew28 Aug 06 '17 at 12:47

ma11hew28 · Answer 3 · 2020-04-30T11:19:29.223

Add the method removingCharacters(in:) to Swift's String type. It returns a new string made by removing the characters in a given character set from the String.

For example:

let string = "+1-202-555-0141"
let set = CharacterSet(charactersIn: "+*#0123456789")
let sanitized = string.removingCharacters(in: set.inverted)
// sanitized is equal to "+12025550141"

Helpers.swift

extension String {
  public func removingCharacters(in set: CharacterSet) -> String {
    let filtered = unicodeScalars.filter { !set.contains($0) }
    return String(String.UnicodeScalarView(filtered))
  }
}

HelpersTests.swift

import XCTest

class HelpersTests: XCTestCase {
  func testRemovingCharacters() {
    let inputText1 = ""
    let set1 = CharacterSet.decimalDigits.inverted
    let sanitized1 = inputText1.removingCharacters(in: set1)
    XCTAssertEqual("", sanitized1)

    let inputText2 = " tab:\tspace: no-break_space: "
    let set2 = CharacterSet.whitespaces
    let sanitized2 = inputText2.removingCharacters(in: set2)
    XCTAssertEqual("tab:space:no-break_space:", sanitized2)

    let inputText3 = " aBc!@#12 $%^&*()-_=+[{]}\\|;:'\"3,<.>/?`~ "
    let set3 = CharacterSet.alphanumerics.inverted
    let sanitized3 = inputText3.removingCharacters(in: set3)
    XCTAssertEqual("aBc123", sanitized3)
  }
}

See also: Convert Array of UnicodeScalar into String in Swift

Why did you go for `lazy` in `unicodeScalars.lazy.filter`? Aren't we using it just below it? — Michal Šrůtek, Apr 30 '20 at 06:33
@MichalŠrůtek, thanks for asking. Great question! I don't know. I had asked a similar question about [oisdk's answer](https://stackoverflow.com/a/32270113/242933). I think you're right though, so I removed the `.lazy` from `unicodeScalars.lazy`. Thanks! :-) — ma11hew28, Apr 30 '20 at 11:16

score 3 · Answer 4 · edited Jan 04 '21 at 10:59

3

works in swift 1&2

let s = "adasdad+3124124+r323*4asdasdbk*($&#@"

let characterSet = NSCharacterSet(charactersInString: "+*#0123456789").invertedSet;
let elements = s.componentsSeparatedByCharactersInSet(characterSet)
let filtered = (elements as NSArray).componentsJoinedByString("")

print(filtered);

edited Jan 04 '21 at 10:59

Olcay Ertaş

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answered Aug 28 '15 at 14:52

Daij-Djan

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How to remove all chars except those in CharacterSet in Swift

4 Answers4