As I know, this is the best way to add a placeholder text to TextEditor in SwiftUI
struct ContentView: View {
		@State var text = "Type here"
		
		var body: some View {
				TextEditor(text: self.$text)
						// make the color of the placeholder gray
						.foregroundColor(self.text == "Type here" ? .gray : .primary)
						
						.onAppear {
								// remove the placeholder text when keyboard appears
								NotificationCenter.default.addObserver(forName: UIResponder.keyboardWillShowNotification, object: nil, queue: .main) { (noti) in
										withAnimation {
												if self.text == "Type here" {
														self.text = ""
												}
										}
								}
								
								// put back the placeholder text if the user dismisses the keyboard without adding any text
								NotificationCenter.default.addObserver(forName: UIResponder.keyboardWillHideNotification, object: nil, queue: .main) { (noti) in
										withAnimation {
												if self.text == "" {
														self.text = "Type here"
												}
										}
								}
						}
		}
}
