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I am trying to get a text field that only accepts numbers but will also accept an empty value (ie. it is an optional field). This is what the textfield looks like:

TextField("Phone Number", value: $phoneNumber, formatter: numberFormatter)
    .disableAutocorrection(true)
    .autocapitalization(.none)

and my number formatter looks like this:

@State private var numberFormatter: NumberFormatter = {
    var nf = NumberFormatter()
    nf.numberStyle = .none
    nf.zeroSymbol = ""    
    return nf
}()

I have tried two different solutions yet both have problems. The first solution is to define phoneNumber as an optional integer Int? so that the TextField will accept a blank input:

@State var phoneNumber: Int? = nil

However, this messes with the TextField so that when I change its value via the app the changes don't update the actual variable phoneNumber. So, when I go to send my data in, phoneNumber still stays at nil. I think this has something to do with the numberFormatter and how it wont't accept nil variables.

So, my second solution is to initialize phoneNumber as an Int like so:

@State var phoneNumber: Int = 0

This solution does update phoneNumber when I change the text in the TextField. However, it will only show a blank space in the TextField box when I type in 0 (because of my .zeroSymbol definition in the numberFormatter). When I try to just put a blank space (ie. delete all the text) and then click out of the TextField, it just reverts back to the number that it was before. This same thing happens when I put a non-numeric entry into the field, which I am okay with because it should only accept numbers, but I want to still allow the user to include a blank entry.

I am using XCode and creating an iOS app. Thank you for any help.

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1
  • phone numbers are incredibly complex, there is PhoneNumberKit to help with that and here is a SwiftUI wrapper gist.github.com/jbnunn/… Commented May 12, 2022 at 20:11

3 Answers 3

Reset to default
2

if you want to accept empty value you can create optional Int variable with value nil and use default formatter i.e. NumberFormatter()

@State var phoneNumber:Int? = nil

TextField("Phone Number", value: $phoneNumber,formatter:NumberFormatter())
    .disableAutocorrection(true)
    .autocapitalization(.none)

Other approaches are create extension and use it like you did

extension Formatter {
    static let valueFormatter: NumberFormatter = {
        let formatter = NumberFormatter()
        formatter.numberStyle = .decimal
        formatter.minusSign   = " - "  // Just for fun!
        formatter.zeroSymbol  = ""     // Show empty string instead of zero
        return formatter
    }()
}

TextField code like

  TextField("Phone Number", value: $phoneNumber,formatter:Formatter.valueFormatter)
                    .keyboardType(.decimalPad)
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Comments

1

A possible solution is to intercept input/output via proxy binding and and perform needed additional validation/processing.

demo

Tested with Xcode 13.3 / iOS 15.4

Here is main part:

TextField("Phone Number", value: Binding(
    get: { phoneNumber ?? 0},
    set: { phoneNumber = phoneNumber == $0 ? nil : $0 }
    ), formatter: numberFormatter)

Complete test module in project

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4 Comments

thank you this solution worked. I am just trying to understand why it works. In the set field, it seems like if phoneNumber is equal to the value in the TextField (denoted by $0), then phoneNumber is set to nil again. Can you help me understand why this produces the result it does? Also, when I type a string in, the Entered text alternates between 0 and nil. Why does this happen? I am fairly new to swift and thank you for all your help.
Also, when I remove the .textFieldStyle(RoundedBorderTextFieldStyle()), the numbers stop updating in the Entered field. Do you know why this could be?
Hmm.. that's weird, I added style just for better visibility of edit field, but it appears that style affects behavior ... that's all about Apple :). Ok with default style they duplicate every input, not just empty, so needed different logic in setter.
@Asperi This doesn't seem to be working anymore. It seems to always force the value to 0 and if I just hit backspace to clear the 0, the app crashes.
0

Another solution that I found is just to make phoneNumber a string with default "". Then, validate it by trying to convert it to an Int via Int(phoneNumber). If Int(phoneNumber) == nil, then raise an error. Otherwise, you now have a new optional integer that can be nil or the integer provided:

var intPhoneNumber: Int?
        if phoneNumber == "" {
            intPhoneNumber = nil
        } else {
            intPhoneNumber = Int(phoneNumber)
            if intPhoneNumber == nil {
                completion(.failure(.custom(errorMessage: "Please enter a valid phone number. Try again.")))
                return
            } else if intPhoneNumber! < 0 {
                completion(.failure(.custom(errorMessage: "Invalid Phone Number. Please enter a valid 10 digit phone number.")))
                return
            } else if numberOfDigits(in: intPhoneNumber!) != 10 {
                completion(.failure(.custom(errorMessage: "Invalid Phone Number. Please enter a valid 10 digit phone number.")))
                return
            }
        }
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