removefromsuperview and addsubview not changing display

I'm pretty new to iOS development, and I'm trying to develop a simple app in which a button changes the subviews. I have a base RootViewController, which displays MiddleView correctly on init. MiddleView has a single button, labeled "First," which is connected (in Interface Builder) to RootViewController's -openFirstView.

Here's how MiddleView is displayed within RootViewController's -viewDidLoad

MiddleViewController *middleTemp = [[MiddleViewController alloc] initWithNibName:@"MiddleView" bundle:nil];
    self.middle = middleTemp;
    self.middle.rootViewController = self;
    [self.view addSubview:middle.view];
    [middleTemp release];

开发者_StackOverflow

So I have the following ViewControllerss: MiddleViewController and FirstController which control MiddleView and FirstView respectively, and a RootViewController which switches between the two.

I've linked this by placing a RootViewController reference in MiddleViewController, and adding

self.middle.rootViewController = self; 

to RootViewController's -viewDidLoad.

-(IBAction)openFirstView:(id)sender{
    [middle.view removeFromSuperview];
    [self.view addSubview:firstController.view];
}

Note: I've tried initializing firstController within -openFirstView, and when it initially didn't run, I moved the initialization to -viewDidLoad and have proven that it is initializing from the nib correctly by displaying FirstView directly in -viewDidLoad

Where firstController is loaded to a reference earlier in code. However, when I run the code and click the button, nothing in the view changes.

I've done some more diagnosing. I've found specifically that -ViewDidLoad in rootViewController is being called twice, once on the original load and once on the first click of the button, and I'm not sure exactly why.

---

It seems you haven't inialize your firstView in the below method

-(IBAction)openFirstView:(id)sender{
    [middle.view removeFromSuperview];
    //First initialize the firstController
    [self.view addSubview:firstController.view];
}