Remove all but numbers from NSString

Question

I have an NSString (phone number) with some parenthesis and hyphens as some phone numbers are formatted. How would I remove all characters except numbers from the string?

Answer 1

Old question, but how about:

  NSString *newString = [[origString componentsSeparatedByCharactersInSet:
                [[NSCharacterSet decimalDigitCharacterSet] invertedSet]] 
                componentsJoinedByString:@""];

It explodes the source string on the set of non-digits, then reassembles them using an empty string separator. Not as efficient as picking through characters, but much more compact in code.

Answer 2

I think currently best way is:

phoneNumber.replacingOccurrences(of: "\\D",
                               with: "",
                            options: String.CompareOptions.regularExpression)

Answer 3

The accepted answer is overkill for what is being asked. This is much simpler:

NSString *pureNumbers = [[phoneNumberString componentsSeparatedByCharactersInSet:[[NSCharacterSet decimalDigitCharacterSet] invertedSet]] componentsJoinedByString:@""];

Answer 4

Though this is an old question with working answers, I missed international format support. Based on the solution of simonobo, the altered character set includes a plus sign "+". International phone numbers are supported by this amendment as well.

NSString *condensedPhoneNumber = [[phoneNumber componentsSeparatedByCharactersInSet:
              [[NSCharacterSet characterSetWithCharactersInString:@"+0123456789"]
              invertedSet]] 
              componentsJoinedByString:@""];

The Swift expressions are

var phoneNumber = " [phone] "
var allowedCharactersSet = NSMutableCharacterSet.decimalDigitCharacterSet()
allowedCharactersSet.addCharactersInString("+")
var condensedPhoneNumber = phoneNumber.componentsSeparatedByCharactersInSet(allowedCharactersSet.invertedSet).joinWithSeparator("")

Which yields [phone] as a common international phone number format.

Answer 5

Based on Jon Vogel's answer here it is as a Swift String extension along with some basic tests.

import Foundation
extension String {
    func stringByRemovingNonNumericCharacters() -> String {
        return self.componentsSeparatedByCharactersInSet(NSCharacterSet.decimalDigitCharacterSet().invertedSet).joinWithSeparator("")
    }
}

And some tests proving at least basic functionality:

import XCTest

class StringExtensionTests: XCTestCase {

    func testStringByRemovingNonNumericCharacters() {

        let baseString = "123"
        var testString = baseString
        var newString = testString.stringByRemovingNonNumericCharacters()
        XCTAssertTrue(newString == testString)

        testString = "a123b"
        newString = testString.stringByRemovingNonNumericCharacters()
        XCTAssertTrue(newString == baseString)

        testString = "a=1-2_3@b"
        newString = testString.stringByRemovingNonNumericCharacters()
        XCTAssertTrue(newString == baseString)

        testString = "[phone]"
        newString = testString.stringByRemovingNonNumericCharacters()
        XCTAssertTrue(newString.characters.count == 10)
        XCTAssertTrue(newString == "9999999999")

        testString = "abc"
        newString = testString.stringByRemovingNonNumericCharacters()
        XCTAssertTrue(newString == "")
    }
}

This answers the OP's question but it could be easily modified to leave in phone number related characters like ",;*#+"

Answer 6

Thanks for the example. It has only one thing missing the increment of the scanLocation in case one of the characters in originalString is not found inside the numbers CharacterSet object. I have added an else {} statement to fix this.

NSString *originalString = @"(123) 123123 abc";
NSMutableString *strippedString = [NSMutableString 
        stringWithCapacity:originalString.length];

NSScanner *scanner = [NSScanner scannerWithString:originalString];
NSCharacterSet *numbers = [NSCharacterSet 
        characterSetWithCharactersInString:@"0123456789"];

while ([scanner isAtEnd] == NO) {
  NSString *buffer;
  if ([scanner scanCharactersFromSet:numbers intoString:&buffer]) {
    [strippedString appendString:buffer];
  }
  // --------- Add the following to get out of endless loop
  else {
     [scanner setScanLocation:([scanner scanLocation] + 1)];
  }    
  // --------- End of addition
}

NSLog(@"%@", strippedString); // "123123123"