Swift Remove control characters from string

Question

I have a Swift app that is scanning a barcode. The barcode sometimes contains a control character at the beginning which is not visible: \u{1D}

I use this method to strip the value from the string but I am looking for something more robust in case some other control characters come up or are inside the string and not at the beginning.

if(articleFilter.hasPrefix("\u{1D}")){
    let stringSize = articleFilter.count - 6
    finalArticleCode = String(articleFilter.suffix(stringSize))
}

score 2 · Answer 1 · edited Dec 04 '19 at 03:29

2

You can use extension to filter other characters except for the numeric.

extension String {

  func filterNonNumeric() -> String {
    return self.components(separatedBy: CharacterSet.decimalDigits.inverted).joined()
  }
}

var str = "\u{1D}01000000000010"
self.sampleLabel.text = str.filterNonNumeric()

The result will be:

edited Dec 04 '19 at 03:29

Nirbhay Singh

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answered Dec 04 '19 at 03:03

Aira Samson

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score 2 · Answer 2 · answered Dec 04 '19 at 03:43

Removing characters from the start and end is called trimming. And the control characters are:

https://developer.apple.com/documentation/foundation/nscharacterset/1416371-controlcharacters

So, like this:

let articleFilterNew = articleFilter.trimmingCharacters(in: .controlCharacters)

score 1 · Answer 3 · edited Dec 04 '19 at 03:45

1

Maybe You can use Replacing String protocol

articleFilter = articleFilter.replacingOccurrences(of: "\u{1D}", with: "")

I think it will solve your problem.

edited Dec 04 '19 at 03:45

pkamb

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answered Dec 04 '19 at 02:52

KpStar

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Is there also a way to use replacingoccurenzces() with .controlCharacters? When I try finalArticleCode = articleFilter.replacingOccurrences(of: .controlCharacters, with: "") I get "Type of expression is ambiguous without more context" as error – Max B Dec 11 '19 at 01:20

score 0 · Answer 4 · answered Dec 04 '19 at 05:01

0

It is very simple by using trimming Characters

var str =  "\u{1D}01000000000010"

let filteredOne = str.trimmingCharacters(in: .controlCharacters)

answered Dec 04 '19 at 05:01

Sandu

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score 0 · Answer 5 · answered Apr 15 '23 at 08:31

For Objective C, I have used the following code and it works

-(NSString *)normalizeText:(NSString *)text {
    NSString *normalizedText = [[text componentsSeparatedByCharactersInSet:NSCharacterSet.controlCharacterSet] componentsJoinedByString:@""];
    NSLog (@"Result: %@", normalizedText);
    
    return normalizedText;
}

For Swift, it is similarly something like

func normalizeText(text: String) -> String {
return text.components(separatedBy: .controlCharacters).joined()
}

Swift Remove control characters from string

5 Answers5