Struct containing array of structs in objective C - objective-c

Question

I have a struct for a tile (all properties are previously-defined enums)
typedef struct {
ShapeType shape;
ColorType color;
PatternType pattern;
IconType icon;
} TileDefinition;
And I want to create another struct that holds 16 tiles, for a "board". Something like this:
typedef struct {
TileDefinition[16]
} BoardDefinition;
And then I want to be able to loop through that, like so:
for(int i=0;i<16;i++) {
TileDefinition tileDef = boardDef[i];
// Do something with tileDef
}
But obviously the setup for the BoardDefinition struct isn't working. How can I set that up? Where should I and shouldn't I use pointers?
Thanks

Answer 1

This is actually a C question.
This bit is fine:
typedef struct {
ShapeType shape;
ColorType color;
PatternType pattern;
IconType icon;
} TileDefinition;
Here, you need to declare BoardDefinition as:
enum { BoardDefinition_NTiles = 16 }; // << declare a constant for your ease of use
typedef struct {
TileDefinition tile[BoardDefinition_NTiles];
} BoardDefinition;
Then to loop through them:
// Given:
BoardDefinition boardDef;
for (size_t i = 0; i < BoardDefinition_NTiles; i++) {
TileDefinition* const tile = &boardDef.tile[i]; // << get a reference to a tile
// member access of the referenced tile:
tile->color.red = 1;
}
The version you wrote creates a copy of the tile:
for (size_t i = 0; i < BoardDefinition_NTiles; i++) {
TileDefinition tile = boardDef.tile[i]; // << creates a copy of the tile, local to the loop body
// member access of the copied tile:
tile.color.red = 1;
}

Answer 2

Option 1: Make BoardDefinition an Objective-C object where it can be set-up in the init method.
Option 2: Use (Objective-)C++ and provide a constructor for struct BoardDefinition.
Option 3: Keep with C and provide an initBoardDefinition(BoardDefinition *boardDef); function.

Answer 3

As trojanfoe suggest, these would be better as Objective-C objects, but if for some reason you don't wont to do that.
You probable want to declare an instance variable of type BoardDefinition in some class for example
#interface MyClass : NSObject
{
BoardDefinition definition;
}
Also you BoardDefinition is wrong it should be something like
typedef struct {
TileDefinition boardDef[16];
} BoardDefinition;
Your loop would then be something like
for(int i=0;i<16;i++) {
TileDefinition tileDef = definition.boardDef[i];
// Do something with tileDef
}
You don't need to use pointers put you could for the TileDefinition in the parent struct something like
typedef struct {
TileDefinition * tileDefinition;
NSUInteger count;
} BoardDefinition;
This way you can have a variable number of TileDefinition. In this case you would have to malloc the tileDefinition soemthing like the following for the class init method.
- (id)init
{
if( (self = [super init]) != nil )
{
definition.count = 16;
definition.tileDefinition = malloc( definition.count * sizeof(*definition.tileDefinition);
}
return self;
}