gistfile1.m

// make the inner dictionaries (probably would use a for loop for this)
NSDictionary *dict1 = [[NSDictionary alloc] initWithObjectsAndKeys:@"value1", @"key", nil];
NSDictionary *dict2 = [[NSDictionary alloc] initWithObjectsAndKeys:@"value2", @"key", nil];
// put them in an array
NSArray *types = [[NSArray alloc] initWithObjects:dict1, dict2, nil];
// now put the array in a dictionary
NSDictionary *finalDict = [[NSDictionary alloc] initWithObjectsAndKeys:types, @"types", nil];