Where is my variable ? objective-c

Question

I initialize a view(Image) through:

Image *myImageView = [[Image alloc]init];
    myImageView.myId = randomImageNumber;
    [myImageView initWithImage:myImage];

At the Image class I do a Log(LOG1) and get the previously set randomImageNumber. Later on, in the very same Class, I do a second Log(LOG2). Why does my second log have no value anymore ?

Here my implementation-file of the Class Image:

@synthesize myId;
-(id) initWithImage: (UIImage *) anImage
{
    NSLog(@"LOG1%d",myId);
    if ((self = [super initWithImage:anImage]))
    {
        self.userInteractionEnabled = YES;
    }
    return self;
}

}
-(void)touchesBegan...
....
- (void) touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
  NSLog(@"LOG2%d",myId);
}

The "return self" empties myId which i declared in the header-file and which was set at the initialisation. How do I prevent that ?

my Headerfile looks like this:

@interface Image : UIImageView 
{
   int myId;
}
@property (assign) int myId;

@end

Answer 1

Couple things in your code. NEVER call init more than once on an object, that just screws up your object.

Change it to this:

Image *myImageView = [[Image alloc] initWithImage:myImage];
myImageView.myId = randomImageNumber;

That is your problem, by default when initializing a subclass of NSObject, all properties are set to 0 (or nil if they are pointers).

If you need to have a default value for myId then do this:

// Image.m

@implementation

// other code

-(id) initWithImage:(UIImage *) image
{
    if (self = [super initWithImage:image])
    {
         self.myId = randomImageNumber;
    }

    return self;
}

// other code

@end