Question

I wanted to know how (if it is possible) to create an NSDictionary that holds an NSArray for every key.

Something like that:

@”FirstKey” – [0], [1], [2], [3]
@”SecondKey” – [0], [1], [2], [3]
@”ThirdKey” – [0], [1], [2], [3]
@”FourthKey” – [0], [1], [2], [3]

Hope you got the idea, thanks ahead!

Answer 1

You can add NSArray instances (or any other collection) as values of an NSDictionary:

NSDictionary *d = [[NSMutableDictionary alloc] init];
[d setValue:[NSArray arrayWithObjects:
               [NSNumber numberWithInteger:0], 
               [NSNumber numberWithInteger:1],
               ...,
               nil]
     forKey:@"FirstKey"];
[d setValue:[NSArray arrayWithObjects:
               [NSNumber numberWithInteger:0], 
               [NSNumber numberWithInteger:1],
               ...,
               nil]
     forKey:@"SecondKey"];
//etc.

Alternatively, if you don’t have too many keys/values:

NSArray *values1 = [NSArray arrayWithObjects:
                    [NSNumber numberWithInteger:0], 
                    [NSNumber numberWithInteger:1],
                    ...,
                    nil];
NSArray *values2 = [NSArray arrayWithObjects:
                    [NSNumber numberWithInteger:0], 
                    [NSNumber numberWithInteger:1],
                    ...,
                    nil];
NSDictionary *d = [NSDictionary dictionaryWithObjectsAndKeys:
                     values1, @"FirstKey",
                     values2, @"SecondKey",
                     ...,
                     nil];