UIViewController initWithNibNamed:bundle: initialized two objects? - ios

Question

I have a UIViewController that I have had in a storyboard for a while with no problems. As my application grew, and I was using that view controller in more and more places, I realized that I should probably make it more portable, rather than have so many segues to it from hither and yon across the board. I've done splits like this before, so I did what I figured was logical here. I selected that view controller, cut it, and pasted into an empty .xib file. After changing each call to performSegueWithIdentifier to an init(nibName:bundle:) and presentViewController, I get a crash, with an object found unexpectedly nil in viewDidLoad()...
I set the value of this object after each init(...) call, just before presenting the view controller. The nil object is called from viewDidLoad(). This is a problem. I just set this, and now it's gone?!
I overrode the init(...) method, and found that self in init(nibName:bundle:) doesn't have the same memory address as self in viewDidLoad(). Also strange.
I overrode the other init() methods, and found that, after I call to present my view, my object is being instantiated again via init(coder:)! The self in here happens to be the exact self where my property is found nil!
The only reason I see for init(coder:) to be called at all is that I am loading my view from a .xib, but I thought this was handled in init(nibNamed:bundle:)? According to the docs, I do indeed get a call to init(coder:) if I'm loading from a storyboard, and doesn't touch the former... It also says that the nib isn't loaded until the controller's view is queried. If I understand it correctly, my view shouldn't get queried until I present the view. As the crash happens only when I present it, the issue likely stems from that.
I'm stuck here. I still need to get this contextual information to the view controller before it's presented. I've even tried making a proxy class to do the instantiating and property setting before presentation, but I still can't shake this second instance! I get one from init(nibName:bundle:), and another from init(coder:). Neither gets presented, and the latter gives me a nil object error. Any help at all in understanding why this is, and how I might work around this bug (feature?) would be much appreciated. Thank you!
Update:
On a whim, I decided to paste the view controller back into the storyboard, separate from the main hierarchy, and try instantiating it by its identifier. It worked! Not entirely sure how, but by George it worked! Now my question is this: Why?? What is so terribly evil and taboo about .xibs that Xcode and iOS won't tell me? I'm not a little flummoxed by this behavior. I'll keep trying with the .xib, if only to keep Xcode from yelling at me about entrance points...

Answer 1

I don't know what dark magic Xcode is doing, but here's two helper methods I wrote to easily instantiate any Storyboard VC - you just need the Storyboard name and VC identifier (optionally, otherwise will initial VC). By splitting up my VCs into many different Storyboards, I avoid dealing with xibs while still keeping things simple. One loads it into a nav controller of your choice, the other just returns it by itself:
struct StoryboardHelper {
///instantiates a VC with (optional) identifier viewController from storyboardName, pushes it to hierarcy of navigationController, and runs setup block on it, animated specifies whether the push is animated
internal static func showStoryboard(storyboardName: String, viewController: String?, navigationController: UINavigationController, animated: Bool = true, setup: (UIViewController) -> () ){
let storyboard = UIStoryboard(name: storyboardName, bundle: nil)
let destinationVC = viewController != nil ? storyboard.instantiateViewControllerWithIdentifier(viewController!) : storyboard.instantiateInitialViewController()!
setup(destinationVC)
navigationController.pushViewController(destinationVC, animated: animated)
}
///instantiates and returns a VC with (optional) identifier viewController from storyboardName
internal static func instantiateViewControllerFromStoryboard(storyboardName: String, viewController: String?) -> UIViewController{
let storyboard = UIStoryboard(name: storyboardName, bundle: nil)
return viewController != nil ? storyboard.instantiateViewControllerWithIdentifier(viewController!) : storyboard.instantiateInitialViewController()!
}
}