Subscription With Block

DataController.h

@interface DataController : NSObject 

- (void) getSubscriptionFromServer onComplete:(void (^)(void)) completionBlock
                                   onCancelled:(void (^)(void)) cancelBlock;

@end

DataController.m

@interface DataController()

@property (nonatomic, copy) void (^onTransactionCancelled)();
@property (nonatomic, copy) void (^onTransactionCompleted)(SKPaymentTransaction *transaction);

@end

@implementation DataController

@synthesize onTransactionCancelled;
@synthesize onTransactionCompleted;



- (void) getSubscriptionFromServer onComplete:(void (^)(void)) completionBlock
                                   onCancelled:(void (^)(void)) cancelBlock{  
  self.onTransactionCompleted = completionBlock;  
  self.onTransactionCancelled = cancelBlock;  
  [self getSubscription];

}

- (void) getSubscriptionFromServer {
  // do some stuff if(success == ture){

  if(success == true){
    if(self.onTransactionCompleted){
      self.onTransactionCompleted();
    } 
  }else{
    if(self.onTransactionCancelled){
      self.onTransactionCancelled();
    } 
  }

}
@end

Subscription.m

- (void) findSubscription{

  [myObject getSubscriptionFromServer onComplete:^ {  
   //Handle subscription call passed  
  }  
  onCancelled:^{  
    //Handle subscription call failed  
  }];

}