fuzzygoat fuzzygoat - 4 months ago 6
Objective-C Question

Accessing View in awakeFromNib?

I have been trying to set a UIImageView background color (see below) in awakeFromNib

[imageView setBackgroundColor:[UIColor colorWithRed:0 green:0 blue:0 alpha:1.0]];


When it did not work, I realised that its probably because the view has not loaded yet and I should move the color change to viewDidLoad.

Can I just verify that I have this right?

gary

EDIT_002:

I have just started a fresh project to check this from a clean start. I setup the view the same as I always do. The results are that the controls are indeed set to (null) in the awakeFromNib. Here is what I have:

CODE:

@interface iPhone_TEST_AwakeFromNibViewController : UIViewController {
UILabel *myLabel;
UIImageView *myView;
}
@property(nonatomic, retain)IBOutlet UILabel *myLabel;
@property(nonatomic, retain)IBOutlet UIImageView *myView;
@end


.

@synthesize myLabel;
@synthesize myView;

-(void)awakeFromNib {
NSLog(@"awakeFromNib ...");
NSLog(@"myLabel: %@", [myLabel class]);
NSLog(@"myView : %@", [myView class]);
//[myLabel setText:@"AWAKE"];
[super awakeFromNib];

}

-(void)viewDidLoad {
NSLog(@"viewDidLoad ...");
NSLog(@"myLabel: %@", [myLabel class]);
NSLog(@"myView : %@", [myView class]);
//[myLabel setText:@"VIEW"];
[super viewDidLoad];
}


OUTPUT:

awakeFromNib ...
myLabel: (null)
myView : (null)
viewDidLoad ...
myLabel: UILabel
myLabel: UIImageView


I would be interested to know if this should work, from the docs it looks like it should, but given the way I usually set things up I can't quite understand why it does not in this case.

Answer

One more answer :-) It looks like you’re getting this behaviour because the controller loads the views lazily. The view is not loaded immediately, it gets loaded the first time somebody calls the view accessor. Therefore at the time you recieve awakeFromNib the NIB loading process is done, but not for the objects inside your views. See this code:

@property(retain) IBOutlet UILabel *foo;
@synthesize foo;

- (void) awakeFromNib
{
    NSLog(@"#1: %i", !!foo);
    [super awakeFromNib];
    NSLog(@"#2: %i", !!foo);
}

- (void) viewDidLoad
{
    NSLog(@"#3: %i", !!foo);
}

This logs:

#1: 0
#2: 0
#3: 1

But if you force-load the view:

- (void) awakeFromNib
{
    [super awakeFromNib];
    [self view]; // forces view load
    NSLog(@"#1: %i", !!foo);
}

The log changes into this:

#3: 1
#1: 1
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