Values in NSMutableDictionary not saved

I have NSMutableArray that contains custom class "Cars". In every car I have NSMutableDictionary property of car images.

Im sending the selected car from car's tableView to another view to design the car. In this view, I want to set few images of the selected car like that:

[theCar.carImages setObject:image forKey:imageName];

the debug show me that the image stored to the dictionary like it should be. but when I go out from the edit view, and back to him again, the images that I stored are gone.

I've tried to send the array with all the cars to the edit view and than I removed the selected car and stored it again after adding the new images but it not working too.

what am i doing wrong?