Referencing a ViewController in AppDelegate - Objective C - ios

Question

I am trying to get a NSMutableArray from another class. I am trying to reference that ViewController that contains the array. Lets say, a has the array I want. b is the class I am going to get that array in.
a.h:
#property (strong, nonatomic) NSMutableArray *selectedCells;
a.m:
#synthesize selectedCells;
AppDelegate.h:
#property (strong, nonatomic) a *create_challengeDelegate;
AppDelegate.m:
#synthesize create_challengeDelegate;
a *create_challengeDelegate = [[a alloc]init];
Right here when I try to reference that ViewController I get an error saying:
Initializer element is not a compile-time constant
I assume it has something to do with it not being able to see the ViewController.
In my b.m:
AppDelegate *app = (AppDelegate*)[[UIApplication sharedApplication] delegate];
app.create_challengeDelegate.selectedCells
My issue is working with initializing the ViewController in the delegate.
Suggestions and thoughts on that?

Answer 1

My suggestion is that you create the selectedCells array in you AppDelegate and send it to A. E.g. in:
AppDelegate.h
#property (nonatomic, strong) NSArray *selectedCells;
AppDelegate.m
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.selectedCells = [NSMutableArray array];
A *viewA = [[a alloc] initWithNibName:#"a" bundle:nil selectedCells:self.selectedCells];
[...]
}
a.h
#property (nonatomic, strong) NSMutableArray *selectedCells;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil selectedCells:(NSMutableArray*)cells;
a.m
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil selectedCells:(NSMutableArray*)cells
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
self.selectedCells = cells;
}
return self;
}
b.m
AppDelegate *app = (AppDelegate*)[[UIApplication sharedApplication] delegate];
NSMutableArray *selectedCells = app.selectedCells;
This way, whenever you make changes to selectedCells it will keep it in the array you send there since selectedCells is a refference to an object which is created in your AppDelegate.
Otherwise, what you are trying to do is access a view which might no longer be available in the memory since the view might have been deallocated.
Also, you create the instance of a but its not set to the AppDelegate's instance of a, its a seperate instance.
Instead of
#synthesize create_challengeDelegate;
a *create_challengeDelegate = [[a alloc]init];
You should have
#synthesize create_challengeDelegate;
self.create_challengeDelegate = [[a alloc] init];
I still strongly recommend you do not access your view this way though.
P.s. #synthesize is no longer necessary.
Edit
This is a better solution.
Selection.h
/**
* The entity for selections
*/
#interface Selection : NSObject
/**
* The Shared Instance
*
* #return Selection The instance
*/
+ (Selection *)sharedInstance;
/**
* Add an item to the selections
*
* #param object id The object to add
*/
- (void)addSelection:(id)object;
/**
* Remove an item from the selections
*
* #param object id The object to remove
*/
- (void)removeObject:(id)object;
/**
* Get the selections
*
* #return NSArray The array with the current selection objects
*/
- (NSArray *)getSelections;
#end
Selection.m
#import "Selection.h"
#interface Selection ()
#property (nonatomic, strong) NSMutableArray *selections;
#end
#implementation Selection
#pragma mark - Public methods
+ (Selection *)sharedInstance
{
static Selection *sharedInstance = nil;
#synchronized(self) {
if (sharedInstance == nil) {
sharedInstance = [[self alloc] init];
}
}
return sharedInstance;
}
#pragma mark - Private methods
- (id)init
{
if (self = [super init])
{
self.selections = [NSMutableArray array];
}
return self;
}
#pragma mark - Manage selection
- (void)addSelection:(id)object
{
[self.selections addObject:object];
}
- (void)removeObject:(id)object
{
[self.selections removeOjbect:object];
}
- (NSArray *)getSelections
{
return [NSArray arrayWithArray:self.selections];
}
Now you can assess your shared singeton in A and/or B by accessing:
[[Selection sharedInstance] addObject:myObject];
[[Selection sharedInstance] removeObject:myObject];
NSArray *array = [[Selection sharedInstance] getSelections];

Answer 2

Is this line inside a method:
a *create_challengeDelegate = [[a alloc]init];
If not that would probably explain your issue. If that's not the problem it might be helpful to post more complete code.