Question

I have a nib that I load the usual way

[NSBundle loadNibNamed:@'AuthorizationWindow' owner:self];

and I see the window show on the screen briefly, and using NSLog() I can confirm that -awakeFromNib is called, but I can’t figure out why the window does not stay on the screen. I had it working correctly for a bit, but now I’m not sure what I changed that messed it up. Thoughts of where to start looking?

Answer 1

I’d guess your window is being deallocated (or if under GC, collected) right out from under you. There are about a million possible reasons for this (none of which we can diagnose from one line of code), but there mere fact you’re using +loadNibNamed:owner: is a warning flag. The reason is that items instantiated in nibs follow the same memory management rules as the rest of Cocoa; if you want them to stick around, you have to retain them (or in GC, keep a reference to them). NSWindowController (and NSViewController too) has some special nib-handling code so that it retains all the top-level objects in its nib when it loads, so that they’ll stick around as long as it does*. However, if you don’t use that, you have to do all that manually.

The real solution is: Don’t use +loadNibNamed:owner:. Instead, create an NSWindowController subclass and set up its -init method like so:

@implementation AuthorizationWindowController - (id)init {     self = [super initWithWindowNibName:@'AuthorizationWindow'];     if (self == nil) return nil;     // any other initialization code     return self; } 

*It also has special code to handle bindings-induced retain cycles that would normally cause it to leak, which is quite a bit more difficult to write yourself. Yet one more reason to use NSWindowController.