Swiftui component how to implement textfield of hidden part of phone number mask (tutorial includes source code)

SwiftUI There is no phone mask tool , Need to use UIKit.
In this paper , We will study ： Use UIKit Written register to SwiftUI Use a mobile mask for the project .

1. stay SwiftUI Create views on

import SwiftUI

struct NumberPhoneMaskView: View {
    
    let maskPhone  = "+X-XXX-XXX-XX-XX"
    @State var text = ""
    
    var body: some View {
        VStack {
            let textChangedBinding = Binding<String>(
                get: {
                FilterNumberPhone.format(with: self.maskPhone, phone: self.text)},
                
                set: { self.text = $0
            })
            TextFieldContainer("+1", text: textChangedBinding)
        }.padding()
    }
}

struct NumberPhoneMaskView_Previews: PreviewProvider {
    static var previews: some View {
        NumberPhoneMaskView()
    }
}

2. Create a TextFieldContainer structure &#x