How does the address of this member variable change in objective-c when the object containing it cannot?

Question

I have been trying to fix this problem for a while and cannot understand why this is happening. It seems that this only happens when "Archiving" the application and running on the device, and not when debugging the application.

I have two classes:

@interface AppController : NSObject <UIApplicationDelegate>
{
    EAGLView * glView;  // A view for OpenGL ES rendering
}

@interface EAGLView : UIView
{
@public
    GLuint framebuffer;
}

- (id) initWithFrame:(CGRect)frame pixelFormat:(NSString*)fformat depthFormat:(GLuint)depth stencilFormat:(GLuint)stencil preserveBackbuffer:(bool)retained scale:(float)fscale msaaMaxSamples:(GLuint)maxSamples;

and I intitializing one object like this:

glView = [ EAGLView alloc ];
glView = [ glView initWithFrame:rect pixelFormat:strColourFormat depthFormat:iDepthFormat stencilFormat:iStencilFormat preserveBackbuffer:NO scale:scale msaaMaxSamples:iMSAA ];
NSLog(@"%s:%d &glView %p\n", __FILE__, __LINE__, glView );
NSLog(@"%s:%d &glView->framebuffer %p\n", __FILE__, __LINE__, &glView->framebuffer );

With initWithFrame, it looks like this:

- (id) initWithFrame:(CGRect)frame
    /* ... */
{
    if( ( self = [super initWithFrame:frame] ) )
    {
        /* ... */
    }
    NSLog(@"%s:%d &self %p\n", __FILE__, __LINE__, self );
    NSLog(@"%s:%d &framebuffer %p\n", __FILE__, __LINE__, &framebuffer );

    return self;
}

The log displays:

EAGLView.mm:399 self 0x134503e90
EAGLView.mm:401 &framebuffer 0x134503f68
AppController.mm:277 glView 0x134503e90
AppController.mm:281 &glView->framebuffer 0x134503f10

How can the address of this member variable change when the object that contains it does not work?

Answer 1

Why not use pointers instead? You are guaranteed to have an address. Change EAGLView as

@interface EAGLView : UIView 
{ 
@public
    GLuint *framebuffer; 
}

framebuffer :

NSLog(@"%s:%d &glView->framebuffer %p\n", __FILE__, __LINE__, glView->framebuffer );

initWithFrame - :

- (id) initWithFrame:(CGRect)frame
{
    unsigned int fbo= opengl_get_framebuffer();
    framebuffer = &fbo;
    NSLog(@"%s:%d &framebuffer %p\n", __FILE__, __LINE__, framebuffer );
}

!