UIView's frame rendering larger than frame

Question

I am trying to add a subview to a UIScrollView. First I instantiate the view controller from the storyboard, then set the view's frame to the application bounds. When I add the view to the UIScrollView, it is clearly larger than it's supposed to be.

CGRect mainFrame = CGRectMake(0, topButtonHeight, screenWidth, screenHeight);

feelingVC = (FeelingViewController *)[self.storyboard instantiateViewControllerWithIdentifier:@"feelingVC"];
feelingVC.delegate = self;
feelingView = feelingVC.view;
[feelingView setFrame:mainFrame];
[self.scrollView addSubview:feelingView];

I can tell because its background color is extending past where it should be. "Debug View Hierarchy" mode in XCode also confirms this. But, if I inspect the view's frame, it prints out what it should be, not what it actually is.

A view of the same size, but generated completely programatically, works as it should:

mainView = [[UIView alloc] initWithFrame:mainFrame];
mainView.backgroundColor = [UIColor blackColor];
[self.scrollView addSubview:mainView];

I'm not sure what could be causing this issue - I've instantiated other views from their view controllers, also via the storyboard, and set their frames without any problems.

EDIT: This is being called from viewDidLoad of the view controller containing the UIScrollView. screenWidth & screenHeight are calculated as such (they are instance variables):

screenWidth = [UIScreen mainScreen].applicationFrame.size.width;
screenHeight = [UIScreen mainScreen].applicationFrame.size.height;

Answer 1

Try to set the view frame in viewWillAppear method.

viewDidLoad is not a good place to set frames (because it called only once when view getting loaded.), the UI components are not properly configured by the system yet.

Also, prefer to use:

screenWidth = [UIScreen mainScreen].bounds.size.width;
screenHeight = [UIScreen mainScreen].bounds.size.height;

instead of

screenWidth = [UIScreen mainScreen].applicationFrame.size.width;
screenHeight = [UIScreen mainScreen].applicationFrame.size.height; 

since bounds has correct positional information taking into consideration the device's orientation in this case.

Or you can just do this, after initializing the mainView inside viewDidLoad: Method

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    mainView.frame = [UIScreen mainScreen].bounds;
}

you can also add this to reconfigure the view frame whenever the subviews are updated:

- (void)viewWillLayoutSubviews { //or viewDidLayoutSubviews
    [super viewWillLayoutSubviews];
    mainView.frame = [UIScreen mainScreen].bounds;
}