Question

I need to use something like a C array:

MyStruct theArray[18][18];

but I cannot define it as a property:

@property (nonatomic) MyStruct theArray[18][18];

then I have to:

@implementation MyClass
{
    MyStruct theArray[18][18];
}

But is this good in term of modern Objective C guideline?

Thanks

Update:

I know I can define the struct as class and use NSMutableArray to handle it, but it is more convenient to use the C array in my case, the main concern is coding guideline and memory issue, as I do not allocate or release the theArray[18][18], not sure what its life cycle is, and I’m using ARC.

Answer 1

Properties cannot be of array type, while public instance variables do not provide sufficient encapsulation. A more Objective C – like approach would be defining a private 2D array, and a pair of methods or a method returning a pointer to access it – something along these lines:

// For small structs you can use a pair of methods:
-(MyStruct)getElementAtIndexes:(NSUInteger)i and:(NSUInteger)j;
-(void)setElementAtIndexes:(NSUInteger)i and:(NSUInteger)j to:(MyStruct)val;

// For larger structs you should use a single method that returns a pointer
// to avoid copying too much data:
-(MyStruct*)elementAtIndexes:(NSUInteger)i and:(NSUInteger)j;