Question

I have been trying for days to get this code to work, but I have no idea what I am doing wrong. Everytime the app wakes up from sleep, or the user closes the app and opens it again (without closing the app from multitasking), I want a label value to change.
In my applicationDidBecomeActive, I am running a counter, which I want to display on whatever viewcontroller is open at that moment.

Code:

- (void)applicationDidBecomeActive:(UIApplication *)application {
counter = counter + 1;

W1G1 *view1 = [[[W1G1 alloc] initWithNibName:@"W1G1" bundle:nil] retain];
[view1 setlabel];

}

In my viewcontroller W1G1, I have the following code:
Code:

- (void) setlabel {
NSString *string = [NSString stringWithFormat:@"%d", counter];  
vocabword.text = string;

}

I have imported W1G1 in my appdelegate, but the code does not run 🙁 Please help!

Thanks

Answer 1

1) When you say ‘the code does not run’ do you mean that? That is, if you put NSLogs in applicationDidBecomeActive: and in setLabel does it show the code is run?

2) I would suspect the code is running. But your code won’t “show the counter on whatever view controller is open at that moment”. Your code creates a new view (view1), but that view won’t be displayed. It is not added as a subview to anything. Your code will also leak. You create a W1G1 object, but it is never released and you throw away any reference you have to it.

To achieve what you want, you could add a subview to the application’s window. Depending how your app delegate is set up, something like the following should do the trick:

  counter++;
  W1G1 *viewController1 = [[W1G1 alloc] initWithNibName:@"W1G1" bundle:nil];
  [viewController1 setlabel: counter];
  [[self window] addSubview: [viewController1 view]]
  // you'll want to save a reference to the viewController somehow so you can release it at a later date

Then in W1G1

- (void) setlabel: (int) counter;
{
    NSString *string = [NSString stringWithFormat:@"%d", counter];  
    vocabword.text = string;
}

There are, of course, lots of other approaches you could take towards this problem. And you’ll need some strategy for removing the W1G1 view that you are adding at some stage, otherwise you’ll just get more and more views added.

Update: You ask (in comments) how to keep track of your viewController throughout lifetime of the app… One approach is to keep track of it in your appDelegate. In the header have something like:

@class W1G1;
@interface MyAppDelegate : : NSObject <UIApplicationDelegate>

{
    // other decelerations
    int counter;
    W1G1 * _myW1G1
}

@property (nonatomic, retain) W1G1* theW1G1

In the .m file include

@synthesize theW1G1 = _myW1G1;

Probably in application:didFinishLaunchingWithOptions: create the viewController, set the property to refer to it, and add its view to the view hierarchy.

 W1G1* theViewController = [[W1G! alloc] initWithNibName: @"W1G1" bundle: nil];
 [[self window] addSubview: [theViewController view]];
 [self setTheW1G1: theViewController];
 [theViewController release];

Then when you want to access the viewController again from with the app delegate use [self theW1G1], e.g.

[[self W1G1] setlabel: counter];