如何创建一个转接表单 UIViewController 到 UICollectionViewController？ - 以编程方式

Question

Can I create an app where I do some stuff and then make a segue to UICollectionViewController?

Now a get this error: " Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'UICollectionView must be initialized with a non-nil layout parameter' "

Of course, I can initiate it in SceneDelegate but I don't want to my UICollectionViewController was the first view.

SceneDelegate when I use ViewController

 func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
    
    guard let scene = (scene as? UIWindowScene) else { return }
    
    window = UIWindow(windowScene: scene)
    window?.rootViewController = ViewController()
    window?.makeKeyAndVisible() 
}

SceneDelegate when i use UICollectionViewController

func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
    
    guard let scene = (scene as? UIWindowScene) else { return }
    
    window = UIWindow(windowScene: scene)
    window?.makeKeyAndVisible()

    let layout = UICollectionViewFlowLayout()
    layout.scrollDirection = .horizontal
    let navController = CollecionViewController(collectionViewLayout: layout)
    window?.rootViewController = navController
    
}

this is my ViewController where I want to make a segue when I press the button

import UIKit

class ViewController: UIViewController {

var button = UIButton()

var button2 = UIButton()

var button3 : UIButton = {
    let button = UIButton(type: .system)
    button.setTitle("Push to 3 View Controller", for: .normal)
    button.backgroundColor = .white
    button.setTitleColor(.black, for: .normal)
    button.frame = CGRect(x: 100, y: 300, width: 200, height: 50)
    button.addTarget(self, action: #selector(didTap3Button), for: .touchUpInside)
    
    return button
}()

@objc func didTap3Button() {
  let rootVC = CollecionViewController()
    let navVC = UINavigationController(rootViewController: rootVC)
    present(navVC, animated: true)
    
}

Answer 1

You should do exactly the thing you did in the second code snippet in didTap3Button , but instead of setting it as the rootViewController , present the navController . Your Collection VC need a layout.

@objc func didTap3Button() {
    let layout = UICollectionViewFlowLayout()
    layout.scrollDirection = .horizontal
    let rootVC = CollecionViewController(collectionViewLayout: layout)
    let navVC = UINavigationController(rootViewController: rootVC)
    present(navVC, animated: true)
}