Problem copying NSMutableArray - iphone

Question

I am trying to copy one array to another:
NSMutableArray *itemsCopy = [[NSMutableArray alloc] initWithArray:self.items copyItems:YES];
but I get the error:
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[Item copyWithZone:]: unrecognized selector sent to instance 0x5a74900'
*** Call stack at first throw:
(
0 CoreFoundation 0x025afc99 __exceptionPreprocess + 185
1 libobjc.A.dylib 0x026fd5de objc_exception_throw + 47
2 CoreFoundation 0x025b17ab -[NSObject(NSObject) doesNotRecognizeSelector:] + 187
3 CoreFoundation 0x02521496 ___forwarding___ + 966
4 CoreFoundation 0x02521052 _CF_forwarding_prep_0 + 50
5 CoreFoundation 0x025108fa -[NSObject(NSObject) copy] + 42
6 CoreFoundation 0x025ab732 -[NSArray initWithArray:range:copyItems:] + 290
7 CoreFoundation 0x02513963 -[NSArray initWithArray:copyItems:] + 99
8 MyViewController 0x0000787d -[MyViewController tableView:didSelectRowAtIndexPath:] + 258
9 UIKit 0x003968f8 -[UITableView _selectRowAtIndexPath:animated:scrollPosition:notifyDelegate:] + 1140
10 UIKit 0x0038d1de -[UITableView _userSelectRowAtIndexPath:] + 219
11 Foundation 0x000a404e __NSFireDelayedPerform + 441
12 CoreFoundation 0x025910c3 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__ + 19
13 CoreFoundation 0x02592704 __CFRunLoopDoTimer + 1364
14 CoreFoundation 0x024ef089 __CFRunLoopRun + 1817
15 CoreFoundation 0x024ee600 CFRunLoopRunSpecific + 208
16 CoreFoundation 0x024ee521 CFRunLoopRunInMode + 97
17 GraphicsServices 0x02db52c8 GSEventRunModal + 217
18 GraphicsServices 0x02db538d GSEventRun + 115
19 UIKit 0x00332e8f UIApplicationMain + 1160
20 MyViewController 0x0000210c main + 102
21 MyViewController 0x0000209d start + 53
)
terminate called after throwing an instance of 'NSException'

Answer 1

You need to make sure all the contents of self.items adopt the NSCopying protocol.
If you just want a shallow copy, send the -mutableCopy message to self.items.
NSMutableArray *itemsCopy = [self.items mutableCopy];

Answer 2

You have to provide your classes with the copyWithZone selector (according to NSCopying protocol) if you are not copying objects that implement that protocol by default.
So if you are copying custom objects you have to implement it. The copy method always calls copyWithZone.. and you must always provide the implementation, it can't know what to copy inside objects by itself..