NSViewController New vs. InitWithNibName issues - objective-c

Question

I am having a weird error with NSViewController where if I allocate a view using the viewcontroller's regular init message, the view created is not my view, but when using the default NIB name, it does work.
Specifically, this code works all the time. It creates the view defined in the nib file, and displays it in the parentView.
+ (void)createTransparentViewCenteredInView:(NSView*)parentView withText:(NSString*)text duration:(NSTimeInterval)duration {
TransparentAccessoryViewController* controller = [[TransparentAccessoryViewController alloc] initWithNibName:#"TransparentAccessoryViewController" bundle:nil];
NSLog(#"%#", [controller.view class]); // Returns "TransparentAccessoryView" -- CORRECT
[parentView addSubview:controller.view];
}
However, the following code works SOME of the time (which is weird in that it doesn't always fail). With some parentViews, it works perfectly fine, and with others, it doesn't. The parent views are just random custom NSViews.
+ (void)createTransparentViewCenteredInView:(NSView*)parentView withText:(NSString*)text duration:(NSTimeInterval)duration {
TransparentAccessoryViewController* controller = [TransparentAccessoryViewController new];
NSLog(#"%#", [controller.view class]); // Returns "NSSplitView" -- INCORRECT
[parentView addSubview:controller.view];
}
The errors that comes up are as follows (I have no idea why it is bringing up an NSTableView, as I don't have an NSTableView here at all. Also, it is weird that it complains about an NSTableView when the type it prints is an NSSplitView):
2013-04-07 21:33:12.384 Could not connect the action refresh: to
target of class TransparentAccessoryViewController
2013-04-07 21:33:12.384 Could not connect the action remove: to target
of class TransparentAccessoryViewController
2013-04-07 21:33:12.385 * Illegal NSTableView data source
(). Must implement
numberOfRowsInTableView: and tableView:objectValueForTableColumn:row:
The NIB file defines a custom subclassed NSView, called TransparentAccessoryView, and hooks this up to the File Owner's view property, standard stuff (all I did was change the custom class name to TransparentAccessoryView). I added an NSLog's to see what was going on, and for some reason, in the second case, the view class type is incorrect and thinks it is an NSSplitView for some reason. The ViewController class is as follows:
#implementation TransparentAccessoryViewController
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Initialization code here.
}
return self;
}
- (void)awakeFromNib {
self.textField.stringValue = #"";
}
+ (void)createTransparentViewCenteredInView:(NSView*)parentView withText:(NSString*)text duration:(NSTimeInterval)duration {
TransparentAccessoryViewController* controller = [[TransparentAccessoryViewController alloc] initWithNibName:#"TransparentAccessoryViewController" bundle:nil];
NSLog(#"%#", [controller.view class]);
[parentView addSubview:controller.view];
}
#end
I thought that the default init message triggers the viewcontroller to load the NIB named after the viewcontroller, which seems to be the case some of the time as the second version of my code works in certain conditions.
Does anyone know why this behavior is occurring at all?

Answer 1

From the docs:
If you pass in a nil for nibNameOrNil then nibName will return nil and
loadView will throw an exception; in this case you must invoke
setView: before view is invoked, or override loadView.
Therefore, if you're initializing a NSViewController with -init, you should call -setView: to set the view controller's view, or override -loadView. In the latter case, you could certainly implement the UIViewController-like behavior that you're probably expecting -- if nibNameOrNil is nil, try to load a nib that has the same name as the class.

Answer 2

I think that when you call init on a NSViewController, you're assuming that the implementation of init for NSViewController searches for a nib with the same name as the view controller and uses it. However, this is undocumented API or at least I can't seem to find any documentation supporting that assumption. The link you posted on your comments doesn't cite any documentation either and even reiterates that this is undocumented and that Apple could change this implementation at any point.
I think to assure that your code works in future versions of the SDK (and since it is already creating undesired behavior), you should not rely on this assumption. To achieve the same outcome simply override init and initWithNibName:bundle: in such a way as explained by this post:
#implementation MyCustomViewController
// This is now the designated initializer
- (id)init
{
NSString *nibName = #"MyCustomViewController";
NSBundle *bundle = nil;
self = [super initWithNibName:nibName bundle:bundle];
if (self) {
...
}
return self;
}
- (id)initWithNibName:(NSString *)nibName bundle:(NSBundle *)bundle
{
// Disregard parameters - nib name is an implementation detail
return [self init];
}