如何将 NSArray 复制到另一个 NSArray？

Question

I have many different NSArrays , and according to the users choice I want one of them to be copied to a new NSArray . How do I copy one NSArray to another?

Answer 1

There can be several ways for this-

1. array1 = [array2 copy];

2. Use initWithArray method.

3. You can also use initWithArray:copyItems: method. (This if for NSMutableArray )

Answer 2

you can use the

NSArray *_newArray = [NSArray arrayWithArray:_oldArray];

or if you prefer better, you can use:

NSArray *_newArray = [[NSArray alloc] initWithArray:_oldArray];

(in that case the object of the first array won't be copied, that get only a retain front he second NSArray , you can remove the object from any array it won't affect the other array, but if you change any object in any NSArray it will be changed in the other one as well because there is both of the old and the new array is working with the same instance of the objects.)

if your plan is to make another instance of the old objects in the new array:

NSArray *_newArray = [[NSArray alloc] initWithArray:_oldArray copyItems:true];

if you are using the ARC, you won't need to do anything else, if you are not, in the case of both -initWithArray: or -initWithArray:copyItems: you should use the [_newArray release]; to release the array after you don't want to use anymore.

Answer 3

As well as

NSArray *newArray = [oldArray copy];

if you need to add/remove from the new array, the simplest way to make a mutable copy is:

NSMutableArray *editableArray = [oldArray mutableCopy];

The above functions both make shallow copies, for deep copy it's as @holex and @rishi mentioned

NSArray *newArray = [[NSArray alloc] initWithArray:oldArray copyItems:true];
NSMutableArray *editableArray = [[NSMutableArray alloc] initWithArray:oldArray copyItems:true];