DatePicker displaying minutes and seconds SwiftUI

Having trouble finding a DatePicker in SwiftUI that displays "mm:ss". displayComponents only has .date and .HourAndMinute.

How do I change the DatePicker to display the minutes and seconds without AM / PM?

struct ContentView: View {

@State private var altEventTime = Date()

public var timeFormatter: DateFormatter {
    let formatter = DateFormatter()
    formatter.dateFormat = "mm:ss"
    return formatter
}

var body: some View {
    Form {
        DatePicker(selection: self.$altEventTime, displayedComponents: .hourAndMinute) {
            Text("Finish time: \(altEventTime, formatter: timeFormatter)")
        }
    }
}

}