Ios 如何在二维数组中添加空对象

我有2D NSMutableArray和我的类对象

例如：

NSMutableArray *myArray2D = [[NSMutableArray alloc] init];

for (int i=0;i<10;i++) {
    NSMutableArray *myArray = [[NSMutableArray alloc] init];

    [myArray addObject:cardView];
    [myArray addObject:cardView];
    [myArray addObject:cardView];

    [myArray2D addObject:myArray];
}

[[myArray2D lastObject] removeAllObjects];

然后我想将这个对象添加回“0对象”

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我怎样才能做到这一点？

我不知道你说的“这个对象”是什么意思，因为你从myArray2D中删除的空数组将在你删除它之后被释放。如果要将空数组添加到myArray2D，只需分配一个新数组并添加它：

NSMutableArray *myArray = [[NSMutableArray alloc] init];
[myArray2D addObject:myArray];

---

我不确定，但也许这就是你的答案

NSMutableArray *myArray2D = [[NSMutableArray alloc] init];

for (int i=0;i<10;i++) {
    NSMutableArray *myArray = [[NSMutableArray alloc] init];

    [myArray addObject:cardView];
    [myArray addObject:cardView];
    [myArray addObject:cardView];

    [myArray2D addObject:myArray];
}

[[myArray2D lastObject] removeAllObjects];
NSMutableArray *tmpArray = [myArray2D lastObject];
[myArray2D removeLastObject];
[myArray2D addObject:tmpArray];

NSMutableArray*myArray2D=[[NSMutableArray alloc]init]；
对于（int i=0；i您创建一个空数组，如下所示：
NSMutableArray*array=[NSMutableArray]；

不能将
nil
对象添加到NSArray

NSMutableArray *myArray2D = [[NSMutableArray alloc] init];

for (int i=0;i<10;i++) {
    NSMutableArray *myArray = [[NSMutableArray alloc] init];

    [myArray addObject:cardView];
    [myArray addObject:cardView];
    [myArray addObject:cardView];

    [myArray2D addObject:myArray];
}

[[myArray2D lastObject] removeAllObjects];
NSMutableArray *tmpArray = [myArray2D lastObject];
[myArray2D removeLastObject];
[myArray2D addObject:tmpArray];