You can't program iOS applications with ReactJS to you need to use Swift (in this case, the frontend part of the development would be SwiftUI). Instead, try adding a WKWebView() to your code. Click here to learn more about WKWebViews.

This is called a context menu. To implement it, you need to add .contextMenu { // Add whatever you want here... including buttons or text } to your button, but it can also work with any other view.

Ummm... you can download Swift Playgrounds and make an app - code it, test it, run it, and even submit it to the app store. No need to bang your head on a wall trying to figure out the answer to this question.

Hover over "Favorites" and click the plus button. There should be a popup that allows you to add a mailbox. In this case, the mailbox is Flagged, which will be available from the picker in the popup. Also, as far as I know, the Flagged mailbox is not included by default in the sidebar.

You have to define the QRScannerController. Since you added your class inside an extension, it the compiler won't be able to find what QRScannerController is.

There are two ways to do it. By the way, in your Xcode project next to your code, there should be a live preview. If it doesn't show, just click on the button to resume live updates. Way 1: import SwiftUI struct ContentView: View {     var body: some View {         // Place the content of your view here.     } } struct ContentView_Previews: PreviewProvider {     static var previews: some View {         ContentView()     } } Way 2: import SwiftUI import PlaygroundSupport struct ContentView: View {     var body: some View {         // Place the content of your view here.     } } PlaygroundPage.current.setLiveView(ContentView())