Embed a UIViewController in Container View programatically

EmbedViewController.swift

// Instantiate
  self.mapViewController = self.storyboard?.instantiateViewController(withIdentifier: "MapViewController") as? MapViewController

    if let mapViewController = self.mapViewController {

        // Add to Container View
        self.mapViewContainerView.addSubview(mapViewController.view)
        self.addChildViewController(mapViewController)
        mapViewController.didMove(toParentViewController: self)
  }
}

Sorry to jump in, but according to Apple's documentation willMove(toParentViewController:) is called when you call addChildViewController(_:), so it doesn't look like you have to call it explicitly...

When your custom container calls the addChildViewController(_:) method, it automatically calls the willMove(toParentViewController:) method of the view controller to be added as a child before adding it.

https://developer.apple.com/documentation/uikit/uiviewcontroller/1621381-willmove

He is correct. I have tested this and in the above example the willMode is called 2x

👍

willMove documentation:

When your custom container calls the addChild(_:) method, it automatically calls the willMove(toParent:) method of the view controller to be added as a child before adding it.

Looks like there is no need to call the willMove method since just after that you call the addChildViewController