Access an NSArray from Every View Controller

问题

I have a quite big NSArray, that i have to use in several view controllers. I get the data from a server and i don't wanna download it always when the user opens a new view.

So how can i define it as a "global variable"?

I can do it with segues, but without them it's not working. I've tried to declare an array called dataToDestinationView in the DestinationViewController, then imported it to the view where the self.arrayToExport is and add the lines above, but doesn't worked. Do i missed something?

DestinationViewController  *dataToNew = [DestinationViewController alloc]init];       
dataToNew.dataToDestinationView = self.arrayToExport;

UPDATED with my try in AppDelegate:

AppDelegate.h

@property (nonatomic, strong) PNChannel *myChannel;

AppDelegate.m

[PubNub requestHistoryForChannel:self.myChannel from:nil to:nil limit:100 reverseHistory:NO withCompletionBlock:^(NSArray *contentArray, PNChannel *channel, PNDate *fromDate, PNDate *toDate, PNError *error) {



+ (NSArray *)mySharedArray
{
    static NSArray *sharedArray = nil;
    if (sharedArray)
        return sharedArray;

    sharedArray = contentArray;
    return sharedArray;
}


}];

In this case i get two errors: Use of undeclared identifier 'self' and Expected identifier or '('. I don't understand it, because self.myChannel is declared in the .h and i'm using the same block elsewhere without the identifier problem.

SECOND UPDATE

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{

 //   [self.window makeKeyAndVisible];

    [PubNub setDelegate:self];

    PFUser *currentChannel = [PFUser currentUser];
    self.myChannel = [PNChannel channelWithName:currentChannel.username
         shouldObservePresence:YES];

}


- (void)getMessage {

    [PubNub requestFullHistoryForChannel:self.myChannel withCompletionBlock:^(NSArray *contentArray, PNChannel *channel, PNDate *fromDate, PNDate *toDate, PNError *error) {


        + (NSArray *)mySharedArray
        {
            static NSArray *sharedArray = nil;
            if (sharedArray)
                return sharedArray;

            sharedArray = contentArray;
            return sharedArray;
        }


        NSLog(@"mokus katona %@", contactArray);

    }];
}

回答1:

Inside your app delegate, declare a static variable, and a method to read it:

static NSArray *_message = nil;

@implementation AppDelegate

+ (NSArray *)message
{
    if (_message)
        return _message;

    AppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
    [appDelegate getMessage];

    return nil;
}

- (void)getMessage {

  [PubNub requestFullHistoryForChannel:self.myChannel withCompletionBlock:^(NSArray *contentArray, PNChannel *channel, PNDate *fromDate, PNDate *toDate, PNError *error) {



      NSLog(@"mokus katona %@", contactArray);

      _message = contactArray;
  }];
}

@end

回答2:

Maybe this can help you.

In your pch file (#project-Prefix.pch) you can create your global variable, available from all spaces. Look below

#ifdef __OBJC__
    NSArray *myArray;
#endif

and in your app delegate, in your - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions, you can fill your array with the server data like this

[PubNub requestFullHistoryForChannel:self.myChannel withCompletionBlock:^(NSArray *contentArray, PNChannel *channel, PNDate *fromDate, PNDate *toDate, PNError *error) {
     NSLog(@"mokus katona %@", contactArray);
     myArray = contactArray;
}];

Now this is only one time loading and myArray will be available in all the controllers, models, view etc.

Let me know if this helps.

来源：https://stackoverflow.com/questions/24355605/access-an-nsarray-from-every-view-controller

标签

ios

objective-c

uiviewcontroller

nsarray