In Objective-C, how does one share data among functions in a view controller?

Aiming for simplicity, how does one share data among functions within a view controller? Ideally, I would like to use a NSMutableDictionary, but my approach doesn’t seem to work (below):

In ViewController.m:

- (void) viewDidLoad{
...
  NSMutableDictionary * movietem = [[NSMutableDictionary alloc] init];
  [movieItem setValue:@“frozen” forKey:@“title” ];
  [movieItem setValue:@“PG” forKey:@“rating” ];
  [movieItem setValue:@“tom cruise” forKey:@“cast” ];  
....
}

-(IBAction) updateTitleBtn:(UIButton *)sender{
…
  [movieItem setValue:@"lion king" forKey:@"title"];
...
} 


-(IBAction) updateCastBtn:(UIButton *)sender{
…
  [movieItem setValue:@"forest whitaker" forKey:@"cast"];
...
} 

Concluding in an error: ‘Unknown receiver ‘movieItem’. Thanks for the input.

movieitem is a local variable thus it can not be used in other methods.

Thus, a better way to share a variable between methods is to declare a property.

Try to add the code below into the head of your XXViewConttroller.m files.

@interface  XXViewConttroller()
@property(nonatomic,strong) NSMutableDictionary* movie;
@end

-(NSMutableDictionary*)movie{
   if(!_movie){
         _movie = [NSMutableDictionary dictionary];
   }
   return _movie;
}

In which I declared a "private property" in .m files and initialized the variable in the getter of the propery.

you can use self.movie to call the property in other part of your code.