NSKeyedArchiver encodeConditionalObject example ios

encodeConditionalObject :forKey:

Encodes a reference to a given object and associates it with a given key only if it has been unconditionally encoded elsewhere in the archive with encodeObject:forKey:.

- (void)encodeConditionalObject:(id)objv forKey:(NSString *)key

Parameters of [NSKeyedArchiver encodeConditionalObject]

objv

The object to encode.

key

The key with which to associate the encoded value. This value must not be nil.

Example of [NSKeyedArchiver encodeConditionalObject]

 @interface GameBoard : NSObject <NSCoding>
    {
        NSMutableArray *_gamePieces;
    }
 @end

 @interface GamePiece : NSObject <NSCoding>
    {
        GameBoard *_gameBoard; // weak reference to avoid retain cycles
    }
 @end

   - (void)encodeWithCoder: (NSCoder *)coder
    {
        [coder encodeConditionalObject: _gameBoard forKey: @"gameBoard"];
    }