Question

I’d like understand why if i try to set value (I.e. setAlphaValue or setTitle) for an object (like a NSButton) in init method nothing happen, but if i call setter function in awakeFromNib it works correctly.

@interface appController : NSObject {
    NSButton *btn;
}
@end;

@implementation appController
-(void)awakeFromNib {
   //it works
   [btn setTitle:@"My title"];
}

-(id)init { 
    self = [super init];
    if(self){
        //it doesn't works
        [btn setTitle:@"My title"];
    }
}
@end

Answer 1

Outlets are set after -init and before -awakeFromNib. If you want to access outlets, you need to do that in -awakeFromNib or another method that’s executed after the outlets are set (e.g. -[NSWindowController windowDidLoad]).

When a nib file is loaded:

1. Objects in the nib file are allocated/initialised, receiving either -init, -initWithFrame:, or -initWithCoder:
2. All connections are reestablished. This includes actions, outlets, and bindings.
3. -awakeFromNib is sent to interface objects, file’s owner, and proxy objects.

You can read more about the nib loading process in the Resource Programming Guide.