How to pass NSObject from one view controller to another - ios

Question

I am using iOS 5 SDK with arc. I want to pass NSObject from VC1 view controller to VC2 view controller, do modification and put back into VC1 controller. I don't want to point same nsobject from both VC1 and VC2 controllers. Whenever I am passing nsobject, it should create a copy of that nsobject and do the modification. (Do not modify actual nsobject).
I have tried below code but it crashes and giving error as
-[ImageObject mutableCopyWithZone:]: unrecognized selector sent to instance 0x1364ec20
Code:
I have NSObject as :
#interface ImageObject : NSObject
#property (copy,nonatomic) NSString *path;
#property (nonatomic, readwrite) int id;
#end
In VC1 view controller:
I am passing my nsobject to VC2 view controller as follows:
VC2ViewController *vc2 = [[VC2ViewController alloc] initWithNibName:#"VC2ViewController" bundle:nil];
vc2.imageObj = [imgObj mutableCopy];
[self.navigationController pushViewController:vc2 animated:YES];
In VC2 view controller:
VC2ViewController.h file
#import "ImageObject.h"
#interface VC2ViewController : UIViewController
#property (retain,nonatomic) ImageObject *imageObj;
#end
VC2ViewController.m file
// modifying nsobject as below
-(void)modifyObject
{
UIViewController *previousViewController = [self.navigationController.viewControllers objectAtIndex:self.navigationController.viewControllers.count-2];
if ([previousViewController isKindOfClass:[VC1ViewController class]])
{
VC1ViewController *parent = (VC1ViewController *) previousViewController;
if(parent != nil)
{
_imageObj.id = 2;
[parent reloadData:_imageObj];
}
parent = nil;
}
[self.navigationController popViewControllerAnimated:YES];
}
Have any idea ? How to resolve this issue?

Answer 1

Your ImageObject class needs to conform to the NSCopying Protocol.
This answer here explains better and shows you how the code looks like.
I also think that you need to use [imgObj copy] instead of [imgObj mutableCopy] because according to apple docs:
The NSMutableCopying protocol declares a method for providing mutable copies of an object.
Only classes that define an “immutable vs. mutable” distinction should adopt this protocol.
Classes that don’t define such a distinction should adopt NSCopying instead.