Swift String Formatter that filters out commas

Is there a Formatter in Swift that filters out commas (or some substring)? It must use the Formatter protocol. Something like this would be great:

static let myCommaFilter : Formatter = {
  // TextFormatter?
  StringFormatter(filter: { input in // (String)->String
    input.replacingOccurrences(of: ",", with: "")
  })
}()

The TextField view in SwiftUI offers an initializer with a Formatter which I thought I could use to filter out commas out of user's input.

you could try something simple like this alternative approach,

struct ContentView: View {
    @State var txt = "something"
    
    var body: some View {
        VStack {
            Text(txt)
            TextField("", text: Binding(
                get: { txt },
                set: { if !$0.contains(",") { txt = $0 }}
                // or alternatively
                // set: { txt = $0.replacingOccurrences(of: ",", with: "")}
            )).border(.red)
        }
    }
    
}

You can create classes that inherit from Formatter and/or FormatStyle, ParseableFormatStyle to use the format variation for SwiftUI.

Here is a rough example

class CommaFormatter: Formatter {
    override func string(for obj: Any?) -> String? {
        guard let obj = obj as? String else{
            return nil
        }
        return obj.replacingOccurrences(of: ",", with: "")
    }
    override func getObjectValue(_ obj: AutoreleasingUnsafeMutablePointer<AnyObject?>?, for string: String, errorDescription error: AutoreleasingUnsafeMutablePointer<NSString?>?) -> Bool {
        obj?.pointee = string.replacingOccurrences(of: ",", with: "") as AnyObject
        return true
    }
    
    override func isPartialStringValid(_ partialString: String, newEditingString newString: AutoreleasingUnsafeMutablePointer<NSString?>?, errorDescription error: AutoreleasingUnsafeMutablePointer<NSString?>?) -> Bool {
        newString?.pointee = partialString.replacingOccurrences(of: ",", with: "") as NSString

        return !partialString.contains(",")
    }
    
}

Then in SwiftUI you can use

TextField("", value: $string, formatter: CommaFormatter())

It will update the string when the user submit