How to generate iOS 13 SwiftUI project in XCode?

Question

So currently in XCode 13, when I create the project for the first time, xcode generates project structure for iOS 14.0+.

I am new to iOS and I want to create a project to target iOS 13.0+. How do I tell XCode to generate project template for iOS 13.0+?

Answer 1

Add this in a .swift file

import UIKit
import SwiftUI

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        // Override point for customization after application launch.
        return true
    }
    
    
    // MARK: UISceneSession Lifecycle
    
    func application(_ application: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options: UIScene.ConnectionOptions) -> UISceneConfiguration {
        // Called when a new scene session is being created.
        // Use this method to select a configuration to create the new scene with.
        return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role)
    }
    
    func application(_ application: UIApplication, didDiscardSceneSessions sceneSessions: Set<UISceneSession>) {
        // Called when the user discards a scene session.
        // If any sessions were discarded while the application was not running, this will be called shortly after application:didFinishLaunchingWithOptions.
        // Use this method to release any resources that were specific to the discarded scenes, as they will not return.
    }
}

class SceneDelegate: UIResponder, UIWindowSceneDelegate {
    
    var window: UIWindow?
    
    
    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
        // Use this method to optionally configure and attach the UIWindow `window` to the provided UIWindowScene `scene`.
        // If using a storyboard, the `window` property will automatically be initialized and attached to the scene.
        // This delegate does not imply the connecting scene or session are new (see `application:configurationForConnectingSceneSession` instead).
        
        // Create the SwiftUI view that provides the window contents.
        let contentView = ContentView()
        
        // Use a UIHostingController as window root view controller.
        if let windowScene = scene as? UIWindowScene {
            let window = UIWindow(windowScene: windowScene)
            window.rootViewController = UIHostingController(rootView: contentView)
            self.window = window
            window.makeKeyAndVisible()
        }
    }
    
    func sceneDidDisconnect(_ scene: UIScene) {
        // Called as the scene is being released by the system.
        // This occurs shortly after the scene enters the background, or when its session is discarded.
        // Release any resources associated with this scene that can be re-created the next time the scene connects.
        // The scene may re-connect later, as its session was not neccessarily discarded (see `application:didDiscardSceneSessions` instead).
    }
    
    func sceneDidBecomeActive(_ scene: UIScene) {
        // Called when the scene has moved from an inactive state to an active state.
        // Use this method to restart any tasks that were paused (or not yet started) when the scene was inactive.            
    }
    
    func sceneWillResignActive(_ scene: UIScene) {
        // Called when the scene will move from an active state to an inactive state.
        // This may occur due to temporary interruptions (ex. an incoming phone call).
        
    }
    
    func sceneWillEnterForeground(_ scene: UIScene) {
        // Called as the scene transitions from the background to the foreground.
        // Use this method to undo the changes made on entering the background.
    }
    
    func sceneDidEnterBackground(_ scene: UIScene) {
        // Called as the scene transitions from the foreground to the background.
        // Use this method to save data, release shared resources, and store enough scene-specific state information
        // to restore the scene back to its current state.
    }
    
    
}

Then Change the Info.plist

Make sure your remove the file that has the @main from the target. The ContentView gets created by the scene.

Answer 2

I have achieved creating an iOS 13 compatible SwiftUI project with the following approach. This has one block for iOS 13 and another block for iOS 14+

Step 0: Create a SwiftUI project with XCode

This will have a main swift file and a ContentView.swift.

// ContentView.swift

import SwiftUI

struct ContentView: View {
    var body: some View {
        Text("Hello")
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

Step 1: Update Info.plist as follows.

Step 2: Update main swift file with the following code.

import UIKit
import SwiftUI

@main
struct MainApp {
    static func main() {
        if #available(iOS 14.0, *) {
            MyView.main()
        } else {
            UIApplicationMain(
                CommandLine.argc,
                CommandLine.unsafeArgv,
                nil,
                NSStringFromClass(AppDelegate.self))
        }
    }
}

@available(iOS 14.0, *)
struct MyView: App {
    var body: some Scene {
        WindowGroup {
            ContentView() // Add another view with content Text("From iOS 14+") to test both block runs
        }
    }
}

class AppDelegate: UIResponder, UIApplicationDelegate {
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        return true
    }

    func application(_ application: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options: UIScene.ConnectionOptions) -> UISceneConfiguration {
        return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role)
    }

    func application(_ application: UIApplication, didDiscardSceneSessions sceneSessions: Set<UISceneSession>) {
    }
}


class SceneDelegate: UIResponder, UIWindowSceneDelegate {

    var window: UIWindow?


    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
        let contentView = ContentView() // Add another view with content Text("From iOS 13") to test both block runs

        if let windowScene = scene as? UIWindowScene {
            let window = UIWindow(windowScene: windowScene)
            window.rootViewController = UIHostingController(rootView: contentView)
            self.window = window
            window.makeKeyAndVisible()
        }
    }

    func sceneDidDisconnect(_ scene: UIScene) {
        //
    }

    func sceneDidBecomeActive(_ scene: UIScene) {
        //
    }

    func sceneWillResignActive(_ scene: UIScene) {
       //
    }

    func sceneWillEnterForeground(_ scene: UIScene) {
       //
    }

    func sceneDidEnterBackground(_ scene: UIScene) {
        //
    }
}

Step 3: Test

1. Install iOS 13 simulator from XCode -> Preferences -> Components
2. Create two separate view files for iOS 13 and iOS 14 and then call it from main swift file.
3. Just use single view file once you tested and verified.
4. Use if #available(iOS 14, *) {} conditions on code block and @available(iOS 15, *) on classes or other objects.