How can I add a bottom line on TextField (SwiftUI)

Question

I use Rectangle() to adding a bottom border on TextField (SwiftUI)

But I want to use protocol TextFieldStyle for a bottom line on TextField Style like an RoundedBorderTextFieldStyle

How can I make a custom style for TextField without using Rectangle?

https://developer.apple.com/documentation/swiftui/staticmember

struct ContentView : View {
    @State private var username = "Text Hellow"
    var body: some View {
        VStack() {
            TextField($username)
                .foregroundColor(Color.yellow)
            Rectangle()
                .frame(height: 1.0, alignment: .bottom)
                .relativeWidth(1)
                .foregroundColor(Color.red)

        }
        .padding()
    }

    func editChanged() {

    }
}

#if DEBUG
struct ContentView_Previews : PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}
#endif

Answer 1

The solution of kontiki does not work with Beta 6, though. So I created a solution where I embed a TextField and a drawn bottom line in a new view. You can just copy the code and use it by writing TextFieldWithBottomLine(placeholder: "My placeholder") Used in a view it looks like:

The first thing I create is a horizontal line:

import SwiftUI

struct HorizontalLineShape: Shape {

    func path(in rect: CGRect) -> Path {

        let fill = CGRect(x: 0, y: 0, width: rect.size.width, height: rect.size.height)
        var path = Path()
        path.addRoundedRect(in: fill, cornerSize: CGSize(width: 2, height: 2))

        return path
    }
}

struct HorizontalLine: View {
    private var color: Color? = nil
    private var height: CGFloat = 1.0

    init(color: Color, height: CGFloat = 1.0) {
        self.color = color
        self.height = height
    }

    var body: some View {
        HorizontalLineShape().fill(self.color!).frame(minWidth: 0, maxWidth: .infinity, minHeight: height, maxHeight: height)
    }
}

struct HorizontalLine_Previews: PreviewProvider {
    static var previews: some View {
        HorizontalLine(color: .black)
    }
}

Next I create a view that contains a TextField and the HorizontalLine below:

import SwiftUI

struct TextFieldWithBottomLine: View {
    @State var text: String = ""
    private var placeholder = ""
    private let lineThickness = CGFloat(2.0)

    init(placeholder: String) {
        self.placeholder = placeholder
    }

    var body: some View {
        VStack {
         TextField(placeholder, text: $text)
            HorizontalLine(color: .black)
        }.padding(.bottom, lineThickness)
    }
}

struct TextFieldWithBottomLine_Previews: PreviewProvider {
    static var previews: some View {
        TextFieldWithBottomLine(placeholder: "My placeholder")
    }
}

To see it in action I created a sample view:

import SwiftUI

struct SampleView: View {
    @State var text: String = ""
    @ObservedObject var model: LoginModel

    init() {
        self.model = LoginModel()
    }

    init(model: LoginModel) {
        self.model = model
    }

    var body: some View {
        TextFieldWithBottomLine(placeholder: "My placeholder").padding(24)
    }

    func initialActions() {

    }

    func reactOnButtonClick() {

    }
}

struct SampleView_Previews: PreviewProvider {
    static var previews: some View {
        SampleView()
    }
}