loadNibNamed from storyboard

Question

This is the scenario: A simple app with two viewcontroller classes and a storyboard with 1 viewcontroller. ViewController 'Super' inherits from UIViewcontroller and implements -loadView and the other view controller, 'Sub', inherits from 'Super'. The view controller class in the storyboard is 'Sub'.

In code:

@implementation SOSuperViewController
- (void)loadView {
    self.view = [[UIView alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    self.view.backgroundColor = [UIColor redColor];
    NSLog(@"%@=> %@", NSStringFromClass([self superclass]), NSStringFromSelector(_cmd));
} 
@end

@implementation SOSubViewController
- (void)awakeFromNib {
    //Outlets are lazy loaded so self.view it is not really set here
    [super awakeFromNib];

    NSLog(@"%@=> %@", NSStringFromClass([self class]), NSStringFromSelector(_cmd));
}

@end

The class for view controller in the storyboard is SOSubViewController. When executing the app you can see -awakeFromNib invoked in the 'Sub' controller and later -loadView invoked in the 'Super' controller and the result is that the screen is red as set in -loadView in the 'Super'.

The first question is: Is there any way to avoid -loadView in 'Super' to be called letting the 'Sub' to get the view from the storyboard?

If using xibs instead storyboards I would implement -loadView in 'Sub' to get the view from the xib file, something like:

- (void)loadView {
    self.view = [[[NSBundle mainBundle] loadNibNamed:@"SOView" owner:self options:nil] firstObject];
}

But I can't know the name of the nib file using storyboards, instead I would need to uses nibBundle and nibName properties if set:

- (void)loadView {
    if (self.nibBundle && self.nibName) {
        [self.nibBundle loadNibNamed:self.nibName owner:self options:nil];
    }
}

But that crashes:

2014-04-10 11:55:11.872 loadViewTest[8941:60b] *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Could not load NIB in bundle: 'NSBundle </Users/nlg/Library/Application Support/iPhone Simulator/7.1/Applications/E36DFC3A-4222-4CE4-A954-CC1C3891DCE1/loadViewTest.app> (loaded)' with name 'vXZ-lx-hvc-view-kh9-bI-dsS''
*** First throw call stack:
(
    0   CoreFoundation                      0x017ec1e4 __exceptionPreprocess + 180
    1   libobjc.A.dylib                     0x0156b8e5 objc_exception_throw + 44
    2   CoreFoundation                      0x017ebfbb +[NSException raise:format:] + 139
    3   UIKit                               0x004e0b7b -[UINib instantiateWithOwner:options:] + 951
    4   UIKit                               0x004e2ada -[NSBundle(UINSBundleAdditions) loadNibNamed:owner:options:] + 165
    5   loadViewTest                        0x00002cff -[SOSuperViewController loadView] + 319
    6   UIKit                               0x0034a0d3 -[UIViewController loadViewIfRequired] + 78
    7   UIKit                               0x0034a5d9 -[UIViewController view] + 35
    8   UIKit                               0x0026a267 -[UIWindow addRootViewControllerViewIfPossible] + 66
    9   UIKit                               0x0026a5ef -[UIWindow _setHidden:forced:] + 312
    10  UIKit                               0x0026a86b -[UIWindow _orderFrontWithoutMakingKey] + 49
    11  UIKit                               0x002753c8 -[UIWindow makeKeyAndVisible] + 65
    12  UIKit                               0x00225bc0 -[UIApplication _callInitializationDelegatesForURL:payload:suspended:] + 2097
    13  UIKit                               0x0022a667 -[UIApplication _runWithURL:payload:launchOrientation:statusBarStyle:statusBarHidden:] + 824
    14  UIKit                               0x0023ef92 -[UIApplication handleEvent:withNewEvent:] + 3517
    15  UIKit                               0x0023f555 -[UIApplication sendEvent:] + 85
    16  UIKit                               0x0022c250 _UIApplicationHandleEvent + 683
    17  GraphicsServices                    0x037e1f02 _PurpleEventCallback + 776
    18  GraphicsServices                    0x037e1a0d PurpleEventCallback + 46
    19  CoreFoundation                      0x01767ca5 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE1_PERFORM_FUNCTION__ + 53
    20  CoreFoundation                      0x017679db __CFRunLoopDoSource1 + 523
    21  CoreFoundation                      0x0179268c __CFRunLoopRun + 2156
    22  CoreFoundation                      0x017919d3 CFRunLoopRunSpecific + 467
    23  CoreFoundation                      0x017917eb CFRunLoopRunInMode + 123
    24  UIKit                               0x00229d9c -[UIApplication _run] + 840
    25  UIKit                               0x0022bf9b UIApplicationMain + 1225
    26  loadViewTest                        0x0000309d main + 141
    27  libdyld.dylib                       0x01e33701 start + 1
)
libc++abi.dylib: terminating with uncaught exception of type NSException

The second question is: Is it possible to load a nib using storyboards without any xib file?

As curiosity, I just discovered the value of self.nibName is vXZ-lx-hvc-view-kh9-bI-dsS with is #object id for the viewcontroller in storyboard#-view-#object id for the view in the viewcontroller# which kind of look right.

checkout this: http://stackoverflow.com/questions/10885585/loading-a-nib-file-that-is-instantiated-from-a-storyboard — pankaj asudani, Apr 10 '14 at 10:11

score 3 · Answer 1 · answered Apr 10 '14 at 10:17

3

You can't.

loadNibNameis supposed to load a nib called SOView.xib in your case.

if you just want to load views, you can create view in separate xib files, but when we're dealing with storyboards, we add only UIViewController inside them (which of course, can contains custom views).

To instantiate a method from a storybard use this method :

[self.storyboard instantiateViewControllerWithIdentifier:@"myControllerID"];

answered Apr 10 '14 at 10:17

Rémy Virin

3,379
23
42

I know that, that was indeed what I would do using regular xib files as mentioned in the question. But the main issue is, if I already have a view loaded from the storyboard and I have it seems like nibBundle and nibName are populated, why can't I use the same approach I used before for xibs? Also, why is super's loadView called although the subclass has its controller in the storyboard? Also, the view controller is already instantiated by the app itself. – Nextorlg Apr 10 '14 at 11:43
Yeah I know that, and I don't know why you can't, I guess Apple wants us storyboards to instantiate controller only, and if you want to deal with view, then you don't have other choice to create xib. I create my views in my controllers, in storybards. But when a view is used twice, I put it in a xib, duplicate views (even in storyboards) can lead to problems while maintaining code. HTH – Rémy Virin Oct 10 '14 at 09:38

loadNibNamed from storyboard

1 Answers1