从情节提要中添加了自定义初始化子视图

Question

I have a subclass of UIViewController that I want to add from the storyboard.

So I'm using what seems the standard methodology:

SubViewController *svc = [self.storyboard instantiateViewControllerWithIdentifier:@"SubViewControllerID"];
[self addChildViewController:svc];
[self.view addSubview:svc.view];

Which is fine but what if I want to call a custom init method on the subview?

I can do something like:

svc = [svc initWithFoo:@"Hello"];

Which seems to have to go after the addSubview call inorder for it to work.

Is this the best way to do this?

Seems a bit unorthodox. Calling an init method on an object that has already been created seems like its no longer truly an init method.

Maybe I should call it setWithFoo: or something and not have it return anything?

Answer 1

If you want to do additional setup to your view controller after you instantiate it form the storyboard you can create some methods in the view controller's class and call them after the instantiate method fo the storyboard.

But be careful, if you try to make changes on any UI component in those methods, they wont be applied, and probably the app will crash. So use those methods to set params to the View Controller like array of objects, or any kind of data, and apply the UI changes for the view controller's view in viewDidLoad/viewWillAppear/viewDidAppear methods of your view controller.

Answer 2

SubViewController *svc = [self.storyboard instantiateViewControllerWithIdentifier:@"SubViewControllerID"];

will cause the SubViewController to be inited with it's - (id)initWithCoder:(NSCoder *)decoder {} method.

Override that method (don't forget to call super )

Answer 3

Essentially I think the answer is that you can't use custom initialisers on ViewControllers added from the storyboard. Instead you have to set properties directly or through a method at the appropriate time in the life cycle as stated above.

Also as mentioned, the VC will be instantiated through initWithCoder , so calling an additional initialiser might be superfluous(?).

I encountered problems trying to use a custom initialiser that contains a call to super if I called it before the subview was added. I would just get a blank view added, I think because the superclass doesn't seem to know about the storyboard at that point. I had more success removing the call to super but that seems wrong.

This case would be more pertinent when adding subviews to a scrollview. For simplicity I left this out of my example.