ivar的属性，指向NSStrings的二维指针数组(property for ivar that points to two-dimensional array of pointers to NSStrings)

 我想创建一个包含NSStrings指针的动态二维c数组的类。 我知道我可以使用包含多个NSArray的NSArray来模拟二维数组，但是如果可能的话我想使用传统的二维c数组来做这个。 除非使用“__unsafe_unretained”，否则ARC不允许将指向NSString的指针简单分配给c数组的元素： 
 
@interface NumberStringsArray : NSObject
{
  @public
  NSString * __unsafe_unretained **_array;
}
 
 为了避免内存泄漏并给出分配给c数组的每个NSString的类所有权中的对象，我将每个NSString对象的指针添加到NSMutableArray。 In - （void）dealloc我释放了获取的内存以创建二维c数组。 
 
 这是我的问题：如何基于_array ivar声明属性，以便我可以将数组的i，j元素称为“foobar.array [i] [j]”而不是“foobar-> array [i ] [J]“？ 
 
 后来放大：除了__bridge之外，我以与回答者非常相似的方式做到了。 我不知道这是否有所作为。 我在这里分配二维数组： 
 
self->_array = (NSString * __unsafe_unretained **)calloc(_columnCount, sizeof(void *));
if (!self->_array)
  return nil;
for (UINT16 i = 0; i < _columnCount; i++)
{
  self->_array[i] = (NSString * __unsafe_unretained *)calloc(_rowCount, sizeof(void *));
  if (!self->_array[i])
  {
    for (UINT16 a = 0; a < _columnCount; a++)
      if (self->_array[a])
        free(self->_array[a]);
    if (self->_array)
      free(self->_array);
    return nil;
  }
}
 
 我使用从逗号分隔值文件生成的子字符串将指向NSString对象的指针放入数组中： 
 
NSArray *numbers = [line componentsSeparatedByString: @","];
for (UINT16 i = 0; i < _columnCount; i++)
{
  NSString *number = @"";
  if (i < [numbers count])
    number = [numbers objectAtIndex: i];
  //
  // save it in owners
  //
  [self.owners addObject: number];
  self->_array[i][j] = number;
}
 
 在 - （void）dealloc我释放所有内存： 
 
-(void)dealloc
{
  for (UINT16 i = 0; i < self.columnCount; i++)
    if (self->_array[i])
      free(self->_array[i]);
  if (self->_array)
    free(self->_array);
}

I want to create a class that contains a dynamic, two-dimensional c-array of pointers to NSStrings. I know I can simulate a two-dimensional array using an NSArray containing multiple NSArrays, but if possible I'd like to do this using a traditional two-dimensional c-array. ARC won't allow a simple assignment of a pointer to an NSString to an element of a c-array unless you use "__unsafe_unretained":
 
@interface NumberStringsArray : NSObject
{
  @public
  NSString * __unsafe_unretained **_array;
}
 
To avoid memory leaks and to give an object in the class ownership of each NSString assigned to the c-array, I add a pointer to each NSString object to an NSMutableArray. In -(void)dealloc I free the memory acquired to create the two-dimensional c-array. 
 
Here's my question: How do I declare a property based on the _array ivar so that I can refer to the i,j element of the array as "foobar.array[i][j]" rather than "foobar->array[i][j]"?
 
Later amplification: I did it in a very similar manner to the answerer except for the __bridge stuff. I don't know if that makes a difference. I allocate the two-dimensional array here:
 
self->_array = (NSString * __unsafe_unretained **)calloc(_columnCount, sizeof(void *));
if (!self->_array)
  return nil;
for (UINT16 i = 0; i < _columnCount; i++)
{
  self->_array[i] = (NSString * __unsafe_unretained *)calloc(_rowCount, sizeof(void *));
  if (!self->_array[i])
  {
    for (UINT16 a = 0; a < _columnCount; a++)
      if (self->_array[a])
        free(self->_array[a]);
    if (self->_array)
      free(self->_array);
    return nil;
  }
}
 
I put pointers to the NSString objects into the array using substrings generated from a file of comma-separated values:
 
NSArray *numbers = [line componentsSeparatedByString: @","];
for (UINT16 i = 0; i < _columnCount; i++)
{
  NSString *number = @"";
  if (i < [numbers count])
    number = [numbers objectAtIndex: i];
  //
  // save it in owners
  //
  [self.owners addObject: number];
  self->_array[i][j] = number;
}
 
In -(void)dealloc I free all the memory:
 
-(void)dealloc
{
  for (UINT16 i = 0; i < self.columnCount; i++)
    if (self->_array[i])
      free(self->_array[i]);
  if (self->_array)
    free(self->_array);
}

原文：https://stackoverflow.com/questions/13735092