Best way to present a view controller - ios

Question

i'm working on multiple frameworks and my question is just a "philosophic" one.
I created an utility function to show view controllers
static func presentViewController(identifier: String, storyboardName: String = "Main", presentationStyle: UIModalPresentationStyle = .fullScreen){
let storyboard = UIStoryboard(name: storyboardName, bundle: InternalConstants.bundle)
var viewResult: UIViewController
if #available(iOS 13.0, *) {
viewResult = storyboard.instantiateViewController(identifier: identifier)
} else {
viewResult = storyboard.instantiateViewController(withIdentifier: identifier)
}
viewResult.modalPresentationStyle = presentationStyle
var top = UIApplication.shared.keyWindow?.rootViewController
while top?.presentedViewController != nil {
top = top!.presentedViewController
}
top!.present(viewResult, animated: true, completion: nil)
}
First of all, is this a correct way to present a view controller or is there a better way?
Then, is it better to present a view controller in a navigation controller or not?

Answer 1

First of all, is a correct way to present a view controller or there is a better way?
instead of a utility make it inside
extension UIViewController {
func ......
}
Then, is better to present a view controller in a navigation controller or not?
a nav is oriented for push/pop but it's also not wrong to use it to present another vc

Answer 2

First of all, is this a correct way to present a view controller or is there a better way?
as long as it's working then it's correct it's just your way of doing this specific thing, but is it the right thing to do as for an iOS and UIKit standpoint the answer is no it's usually is a bad thing to present a viewController by looking at the rootViewController's presentedViewController because it's not guaranteed that the last presentedViewController you find is a good thing to present on it and you won't know until it breaks, that presentedViewController could be a UISearchController and if you use UIContentContainer or ContainerView from storyboards, you might have a small viewController that is just a UISlider at the end, this could be bad for viewController appearance and disappearance
another problem that you will face is when you need to pass data to and from the viewController that you presenting by using this approach you don't even have a reference to the viewController you are presenting, because you are only passing an identifier
from an MVC standpoint you should never try to present viewController from a UIView by calling your function from your view directly Thats Bad Practice
if you take a look at the UIKit SDK if you ever try to present any system UIViewController you will find that you have the responsibility of instantiating and presenting the vc for example UIImagePickerController, UIActivityViewController, UIDocumentPickerViewController, UIDocumentMenuViewController, UIPrinterPickerController, UIVideoEditorController
Apple themselves didn't go for providing a function to present theirs system vcs
instead if you are developing a framework and don't want to give users access to your viewControllers you should make you own window and give it a rootViewController
Apple also has many examples for this too, in the AuthenticationServices framework for security reasons you should not have a reference to the safari web browser they have something called ASWebAuthenticationSession that controls the flow of presenting and dismissing the Safari Web ViewController by calling start() and cancel() functions
also the users of your framework will not always want to present your viewController with the default presentation animation they might want to use custom viewContollers animations which they will need access to the transitioningDelegate property on the viewController
imagine every public useful property on UIViewController will not be accessible if you go with this approach
Then, is it better to present a view controller in a navigation controller or not?
as for this part it's totally fine to present anything on a navigationController
Storyboards headaches
as for the storyboards initialization headaches there are plenty of articles out there talking about optimizing the storyboards initialization call site for that I would recommend doing something like this
extension UIStoryboard {
enum AppStoryBoards: String {
case
login,
main,
chat,
cart
}
convenience init(_ storyboard: AppStoryBoards, bundle: Bundle? = nil) {
self.init(name: storyboard.rawValue.prefix(1).capitalized + storyboard.rawValue.dropFirst(), bundle: bundle)
}
}
This way you can initialize a storyboards using enum which improves the call site to be like this
let login = UIStoryboard.init(.login)
then you can have another extension for view controller initialization like this
extension UIStoryboard {
func instantiateInitialVC<T: UIViewController>() -> T {
return self.instantiateInitialViewController() as! T
}
func instantiateVC<T: UIViewController>(_: T.Type) -> T {
return self.instantiateViewController(withIdentifier: String(describing: T.self)) as! T
}
}
and you can then call it like this
let loginVC = UIStoryboard.init(.login).instantiateInitialVC()
or this
let loginVC = UIStoryboard.init(.login).instantiateVC(LoginViewController.self)
by doing that you improve your overall code for presenting any viewController
let dvc = UIStoryboard.init(.login).instantiateVC(LoginViewController.self)
dvc.plaplapla = "whatever"
present(dvc, animated: true)