Deep Copy and Shallow Copy

Question

I have read the answer for difference between deep copy and shallow copy from the post, What is the difference between a deep copy and a shallow copy? . Now I got some doubt

Answer 1

First of all, NSArray's don't have a deep copy function. However, you can make a deep copy function by doing the following:

@interface NSArray(deepCopy)

-(NSArray *) deepCopy;

@end

@implementation

-(NSArray *) deepCopy
{
    NSMutableArray *ret = [NSMutableArray array];

    for (id val in self)
    {
        if ([val conformsToProtocol:@protocol(NSCopying)])
        { 
            [ret addObject:[val copy]];
        }
        else
        {
           [ret addObject:val];
        }
    }

    return ret;
}

@end 

Second of all, newArray = oldArray does not copy the array. It simply makes newArray point to the array that oldArray points to.

Third, +arrayWithArray: does a shallow copy of the array, meaning the individual objects are NOT copied.