Question

How to call array from the model-class in my NSWindowController? The valueArray is set in AppDelegate, to the model-class ValueItem:

@interface AppDelegate : NSObject <NSApplicationDelegate>
{
    ValueItem *vi;
    ResultWindowController *rwc;
    IBOutlet NSArrayController *outArrayController;
}

and

@implementation AppDelegate
....
- (IBAction)pushOk:(NSButton *)sender
{
    self->vi = [[ValueItem alloc]init];
    [vi setValueArray:[outArrayController arrangedObjects]];
    NSLog(@"vi.valueArray is:%@", vi.valueArray);

    if (rwc)
    {
        [rwc close];
    }
    rwc = [[ResultWindowController alloc] init];
    [rwc setShouldCascadeWindows:NO];
    [rwc showWindow:self];

}

Calling NSLog(@"vi.valueArray is:%@", vi.valueArray); return the arrays content just fine. But when I try to use it in my other NSWindowController it return always NULL:

@interface ResultWindowController : NSWindowController
{
    ValueItem *vi;
    NSNumber *resultAverage;
}

and

@implementation ResultWindowController
@synthesize resultAverage;
...

- (IBAction)pushChange:(NSButton *)sender
{
    [self calculateAverage];
    [_outputLabel setDoubleValue:[resultAverage doubleValue]];
    NSLog(@"resultAverage is:%@", resultAverage);
    NSLog(@"vi.valueArray is:%@", vi.valueArray);
}

-(void)calculateAverage
{
    resultAverage = [vi.valueArray valueForKeyPath:@"@avg.nomValue"];
}

I can’t find the missing link? What do I miss here?
Thanks!

Answer 1

You have two separate and unrelated instances of ValueItem *vi in your two classes. That explains why you set it up in the first class, but in the second vi is still nil.

You should be able to fix it by doing this:

rwc = [[ResultWindowController alloc] init];
[rwc setVi:self->vi];                // <--- this
[rwc setShouldCascadeWindows:NO];
[rwc showWindow:self];

In order to do that, you should define a proper setter method in RootWindowController.

Alternatively, if you want to make your AppDelegate act as a model, you could do:

ValueItem *vi = [(AppDelegate*)[UIApplication sharedApplication].delegate vi];

when you need to access vi. You could then remove the vi ivar declared in RootWindowController (since you would access directly the one in you app delegate).

Actually, it would be better creating a separate class acting as a model. It could be a singleton and you could access it like this:

ValueItem *vi = [MyModel sharedModel].vi;

far more readable and concise.