SwiftUI TextField max length

Question

Is it possible to set a maximum length for TextField? I was thinking of handling it using onEditingChanged event but it is only called when the us

Answer 1

Write a custom Formatter and use it like this:

    class LengthFormatter: Formatter {

    //Required overrides

    override func string(for obj: Any?) -> String? {
       if obj == nil { return nil }

       if let str = (obj as? String) {
           return String(str.prefix(10))
       }
         return nil
    }

    override func getObjectValue(_ obj: AutoreleasingUnsafeMutablePointer?, for string: String, errorDescription error: AutoreleasingUnsafeMutablePointer?) -> Bool {

                obj?.pointee = String(string.prefix(10)) as AnyObject
                error?.pointee = nil
                return true
            }

        }
}

Now for TextField:

struct PhoneTextField: View {
        @Binding var number: String
        let myFormatter = LengthFormatter()

        var body: some View {
            TextField("Enter Number", value: $number, formatter: myFormatter, onEditingChanged: { (isChanged) in
                //
            }) {
                print("Commit: \(self.number)")
            }
            .foregroundColor(Color(.black))
        }

    }

You will see the correct length of text get assigned to $number. Also, whatever arbitrary length of text is entered, it gets truncated on Commit.