深度复制NSArray [英] Deep copying an NSArray

问题描述

有没有任何内置的函数允许我深度复制 NSMutableArray ？

Is there any built-in function that allows me to deep copy an NSMutableArray?

，有人说 [aMutableArray copyWithZone：nil] 作为深度复制。但我试过，它似乎是一个浅拷贝。

I looked around, some people say [aMutableArray copyWithZone:nil] works as deep copy. But I tried and it seems to be a shallow copy.

现在我手动做一个为 loop：

Right now I am manually doing the copy with a for loop:

//deep copy a 9*9 mutable array to a passed-in reference array

-deepMuCopy : (NSMutableArray*) array 
    toNewArray : (NSMutableArray*) arrayNew {

    [arrayNew removeAllObjects];//ensure it's clean

    for (int y = 0; y<9; y++) {
        [arrayNew addObject:[NSMutableArray new]];
        for (int x = 0; x<9; x++) {
            [[arrayNew objectAtIndex:y] addObject:[NSMutableArray new]];

            NSMutableArray *aDomain = [[array objectAtIndex:y] objectAtIndex:x];
            for (int i = 0; i<[aDomain count]; i++) {

                //copy object by object
                NSNumber* n = [NSNumber numberWithInt:[[aDomain objectAtIndex:i] intValue]];
                [[[arrayNew objectAtIndex:y] objectAtIndex:x] addObject:n];
            }
        }
    }
}

推荐答案

由于 Apple docs 状态， p>

As the Apple docs state,

如果你只需要一个一级的复制，你可以显式调用一个...

If you only need a one-level-deep copy, you can explicitly call for one...

NSMutableArray *newArray = [[NSMutableArray alloc] initWithArray:oldArray copyItems:YES];

上述代码创建一个新数组，其成员是浅拷贝

The above code creates a new array whose members are shallow copies of the members of the old array.

请注意，如果您需要深度复制整个嵌套数据结构 - 链接的Apple文档称为真正的深层副本 - 这种方法是不够的 - 请看这里的其他答案。

Note that if you need to deeply copy an entire nested data structure - what the linked Apple docs call a "true deep copy" - then this approach will not suffice - see the other answers here.

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