CODEWITHSUNDEEP
core-datasingletonglobal-variables
Japa
Japa

Reputation: 632

Properly use a singleton in objective c

I´m lost on this one, already read some things all over the internet but my problem is that i need to understand how to properly use the singleton. My problem is, at some point in my app i do what is below:

myVariable = [NSEntityDescription insertNewObjectForEntityForName:@"Entity" 
          inManagedObjectContext:context];

I need to preserve myVariable and use it in other views, and i read somewhere that this is the best way if i want to use a variable through all my views. I have followed this example but i really don´t know how to use it, can someone explain it to me?:

@interface DataLoader : NSObject {
   NSString *someProperty; 
   //(i think i need myVariable here, and not type NSString)
}

@property (nonatomic, retain) NSString *someProperty;

+ (id)sharedManager;
@end


@implementation DataLoader

+(id)sharedInstance  {
   static dispatch_once_t p=0;
   __strong static id _sharedObject = nil;
   dispatch_once(&p, ^{
    _sharedObject = [[self alloc]init];
   });

return _sharedObject;
}

@end

How can i set myVariable and then in another views use it?

Regards

Upvotes: 0

Views: 56

Answers (1)

Mundi
Mundi

Reputation: 80265

The usual way is to have the controllers pass the variable on to the next one whenever they are pushed on the navigation stack, e.g. in prepareForSegue:. Just give your view controllers a strong @property to keep track of it.

SomeViewController *nextVC = segue.destinationController;
nextVC.myVariable = self.myVariable;

That is how it is done in many instances of Apple's sample code with managed object context, it certainly is good pattern.

Upvotes: 1

Related Questions