Deep copy of an NSMutableArray of custom objects with NSMutableArray members

Question

I'm trying to make a deep copy of an NSMutableArray whose objects are instances of a custom class similar to this:

@interface CustomParent : NSObject
@property NSInteger Id;
@property (strong, nonatomic) NSString *IdStr;
@property (weak, nonatomic) NSDate *Date; 
@property (strong, nonatomic) NSMutableArray *CustomChildren;
@property (strong, nonatomic) CustomType *Type;
@property float Value;
@end

I know there are lots of posts dealing with copying objects, but I don´t find examples for getting a complete copy of objects with collection members or properties. NSMutableArray *dstArray = [[NSMutableArray alloc] initWithArray:srcArray copyItems:YES]; raises an exception involving the copyWithZone method.

How can I do this? Thanks!

take a look at the NSCoding protocol : https://developer.apple.com/library/mac/#documentation/cocoa/reference/foundation/Protocols/NSCoding_Protocol/Reference/Reference.html — Lescai Ionel, Jun 27 '13 at 13:34
@GabrielePetronella I read the post you referred and it seems to work, thanks! — AppsDev, Jun 28 '13 at 17:55
@LescaiIonel I tried `NSCoding` before and it takes a lot of time for copying many objects connected to a class. Thins `NSCopying` should be faster. — Alex Cio, Feb 17 '15 at 15:01

score 13 · Accepted Answer · edited May 23 '17 at 12:17

13

In order to deep copy the content of the array

[[NSMutableArray alloc] initWithArray:srcArray copyItems:YES];

will send copyWithZone: to every object inside the collection. If they don't respond to this selector, you'll get a crash.

Have your CustomParent class to conform to the NSCopying protocol and you're done.

Here's some extra info on how do achieve it: Implementing NSCopying

edited May 23 '17 at 12:17

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answered Jun 27 '13 at 13:35

Gabriele Petronella

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Deep copy of an NSMutableArray of custom objects with NSMutableArray members

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