Question

In the header, I declare my

NSString *name;

Variable. Then I make it a property with

@property (nonatomic,retain) NSString *name;

And I synthesize it in the implementation

@synthesize name;

And, immediately, give it a value in the init method:

name = @"HELLO";

Later I add a child to my scene. This child, later, will try to access this property. It goes like

Battle *battleScene = (Battle*)self.parent;
NSLog(@"%@",battleScene.name);

But I get “null”. Why is that?

Answer 1

One reason for this may be that self.parent is nil. This happens if you try to run the code in the init method of the child node.

CCNode* child = [[[CCNode alloc] init] autorelease];
// at this point the init method is run but parent of the child is still nil …
…

[self addChild:child];
// now the parent of the child is set, after it's been added to the hierarchy

If you do run this in the init method, move that code to the onEnter method instead:

-(id) init
{
     // self.parent == nil !!
} 

-(void) onEnter
{
    // self.parent is guaranteed to be non-nil in onEnter
    Battle *battleScene = (Battle*)self.parent;
    NSLog(@"%@",battleScene.name);
}