Try it like this: Instead of setting the cornerRadius to the Button use an overlay for the inside View:

    Button(action: {        print("sign up bin tapped")    }) {        Text("SIGN UP")            .frame(minWidth: 0, maxWidth: .infinity)            .font(.system(size: 18))            .padding()            .foregroundColor(.white)            .overlay(                RoundedRectangle(cornerRadius: 25)                    .stroke(Color.white, lineWidth: 2)        )    }

Works for me. Let me know if it helps!

Updated for Swift 5 & iOS 13.4+ with Press States!

None of the examples worked for buttons with both dark and white background colors as well as none of them had press state updates, so I built this LargeButton view that you can see below. Hope this helps, should be pretty simple to use!

Example Photos

Example Use

// White button with green border.LargeButton(title: "Invite a Friend",             backgroundColor: Color.white,             foregroundColor: Color.green) {                        print("Hello World")                    }// Yellow button without a borderLargeButton(title: "Invite a Friend",             backgroundColor: Color.yellow) {                        print("Hello World")                    }

Code

struct LargeButtonStyle: ButtonStyle {        let backgroundColor: Color    let foregroundColor: Color    let isDisabled: Bool        func makeBody(configuration: Self.Configuration) -> some View {        let currentForegroundColor = isDisabled || configuration.isPressed ? foregroundColor.opacity(0.3) : foregroundColor        return configuration.label            .padding()            .foregroundColor(currentForegroundColor)            .background(isDisabled || configuration.isPressed ? backgroundColor.opacity(0.3) : backgroundColor)            // This is the key part, we are using both an overlay as well as cornerRadius            .cornerRadius(6)            .overlay(                RoundedRectangle(cornerRadius: 6)                    .stroke(currentForegroundColor, lineWidth: 1)        )            .padding([.top, .bottom], 10)            .font(Font.system(size: 19, weight: .semibold))    }}struct LargeButton: View {        private static let buttonHorizontalMargins: CGFloat = 20        var backgroundColor: Color    var foregroundColor: Color        private let title: String    private let action: () -> Void        // It would be nice to make this into a binding.    private let disabled: Bool        init(title: String,         disabled: Bool = false,         backgroundColor: Color = Color.green,         foregroundColor: Color = Color.white,         action: @escaping () -> Void) {        self.backgroundColor = backgroundColor        self.foregroundColor = foregroundColor        self.title = title        self.action = action        self.disabled = disabled    }        var body: some View {        HStack {            Spacer(minLength: LargeButton.buttonHorizontalMargins)            Button(action:self.action) {                Text(self.title)                    .frame(maxWidth:.infinity)            }            .buttonStyle(LargeButtonStyle(backgroundColor: backgroundColor,                                          foregroundColor: foregroundColor,                                          isDisabled: disabled))                .disabled(self.disabled)            Spacer(minLength: LargeButton.buttonHorizontalMargins)        }        .frame(maxWidth:.infinity)    }}

Swift 5 & iOS 14 – Borders also react when pressed

struct PrimaryButtonStyle: ButtonStyle {    func makeBody(configuration: Configuration) -> some View {        configuration.label            .padding(5)            .foregroundColor(configuration.isPressed ? Color.red.opacity(0.5) : .red)            .overlay(                RoundedRectangle(cornerRadius: 8)                    .stroke(configuration.isPressed ? Color.red.opacity(0.5) : .red, lineWidth: 1.5)            )     }}

How to use

Button("Hide") {    print("tapped")}.buttonStyle(PrimaryButtonStyle())

borders also react when pressed