Unable to access "center" property of UIView from outside the class - objective-c

Question

I have an instance of UICollectionViewCell ( lets call it c ).
c has a property child of type B*
#property (strong) B* child;
in B there is a declaration
#property (strong) C* parent;
in C.m I set
self.child.parent = self
In B.m I have code :
position = self.parent.center.x;
For some reason I can not access center property of UIVIew from outside the instance. Is it private ? I looked in UIView.h and in the documentation. I dont see it being private.
Accessing self.parent in B.m is giving me the correct values ...
So why cant I access it ? In C.m
self.center
is working as expected ...
EDIT : With the real code
This is the so-called "C.h"
#import <UIKit/UIKit.h>
#import "UIMovableImage.h"
#interface LetterCollectionCell : UICollectionViewCell
#property (weak, nonatomic) IBOutlet UIImageView *letterCellView;
#end
This is "B.h"
#import <UIKit/UIKit.h>
#class LetterCollectionCell;
#interface UIMovableImage : UIImageView
{
CGPoint currentPoint;
}
#property (strong) LetterCollectionCell* parent;
#end
This is "C.m"
#import "LetterCollectionCell.h"
#import "LettersCollection.h"
#implementation LetterCollectionCell
-(void)PrepareImage:(int)index Hint:(BOOL)hint Rotate:(BOOL)rotate
{
if ([_letterCellView respondsToSelector:#selector(parent)])
{
UIMovableImage* temp = ((UIMovableImage*)self.letterCellView);
temp.parent = self;
}
}
#end
And here is the "B.m"
#import "UIMovableImage.h"
#import "LetterCollectionCell.h"
#implementation UIMovableImage
- (void) touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event
{
// Get active location upon move
CGPoint activePoint = [[touches anyObject] locationInView:self.parent];
// Determine new point based on where the touch is now located
CGPoint newPoint = CGPointMake(self.parent.center.x + (activePoint.x - currentPoint.x),
self.parent.center.y + (activePoint.y - currentPoint.y));
}
#end
Please note that the LetterCollectionCell's letterCellView is of type UIImageView and not of type UIMovableImage. The reason is that I want to keep this declaration as a placeholder. In the Interface Builder I have two scenes where the LetteCollection is used. In one scene I set the imageview to be of UIMovableImage ( thru Inspector Window ) and at the other I left the image to be of type UIImageView. So the run-time will create the proper class upon different scenes and at the collection I check : if the image has a property "parent" - I set it up. Otherwise I dont.
It works fine, the assignment works just fine.... but the access is not

Answer 1

The only reason you wouldn't have access to the property would be that the class is not aware of it (forward declaration). Therefore, you must have a missing #import "C.h" in B's implementation file.
Perhaps an example is necessary to appease the downvoter, so let's use yours:
Here's what B's header should look like
//Give us the ability to subclass UICollectionViewCell without issue
#import <UIKit/UIKit.h>
//forward declare a reference to class B. We cannot access it's properties until we
//formally import it's header, which should be done in the .m whenever possible.
#class B;
#interface C : UICollectionViewCell
//Declare a child property with a strong reference because we are it's owner and creator.
#property (strong, nonatomic) B* child;
#end
Now C's header.
//import foundation so we can subclass NSObject without a problem.
#import <Foundation/Foundation.h>
//Forward-declare classe C so we don't have to #import it here
#class C;
#interface B : NSObject
//keep an unretained reference to our parent because if the parent and the child have
//strong references to each other, they will create a retain cycle.
#property (unsafe_unretained, nonatomic) C* parent;
#end
Now that that's out of the way, here's the implementation of C that you are most likely using:
#import "C.h"
#import "B.h"
#implementation C
-(id)init {
if (self = [super init]) {
self.child = [[B alloc]init];
self.child.parent = self;
}
return self;
}
#end
Not too bad, but here's the problem:
#import "B.h"
#implementation B
-(id)init {
if (self = [super init]) {
CGFloat position = self.parent.center.x; //ERROR!
}
return self;
}
#end
because C's only declaration that it has a center property (or rather that it's superclass has a center property), and C's type are in the C.h file, B has no knowledge of C's properties without an explicit #import of C.h.

Answer 2

I found the reason.
The whole question was barking at the wrong tree.
In fact, the bug was at the other place and I just kept looking at the "Invalid Expression" int the debugger's watch window.
To sum up : accessing the "center" property worked just find under the circumstances described in the original question. The "Invalid Expression" of the debugger and a bug in a different place made me chase a wrong thing.
I +1d the generally correct answers and comments but can not accept them since it may mislead people.
Thanks to all for the help and the effort

Answer 3

According to the sequence of your question it seems to me that you start with setting the C.m but on that line code the child instance is not set yet.. that self.child = nil so setting self.child.parent = self will give you no result... Accordingly on B.m will not have the access to the parent object...
if i am correct just set your child instance object -- self.child = B* --- before set self.child.parent = self......