Question

I’ve been working on an error in my program but I cannot seem to find a solution.

When the user opens the camera the UIImagePickerController is displayed and works great.
Although when he presses the home button on the iPhone I want to remove an object from an NSMutableArray.

For instance:
The user opens the camera.
An object is added to an NSMutableArray in another class.
The user presses the home button
The object should be removed.

I can’t call the remove method when the application moves to the background because I need the other object to remain in the array for background location services.

Is there a way to catch the event when either pressing the home button or when the UIImagePicker closes itself by the home button event?

Answer 1

You will have to post notication. For that in appDelegate method:

 - (void)applicationDidEnterBackground:(UIApplication *)application
 {
   [[NSNotificationCenter defaultCenter] postNotificationName:@"objectRemover" object:nil];
 }

Now were you open UIImagePickerController in your view controller and its viewDidLoad method

-(void)viewDidLoad
{
 [[NSNotificationCenter defaultCenter]addObserver:self selector:@selector(removeObject) name:@"objectRemover" object:nil];
}

add selector method in your view controller were you will remove your object as it will be called when home button is pressed.

-(void)objectRemover
{
   // Your code remove object from array
}