Question

I’m trying to get and set from an NSDictionary with NSNumbers as the keys. I think I’m doing things according to this answer https://stackoverflow.com/a/6891489/194309 but my code below returns null values.

- (void)viewDidLoad {
    [super viewDidLoad];

    NSInteger const SET1 = 1;
    NSInteger const SET2 = 2;


    videoKeyOfTag = [[NSDictionary alloc] initWithObjectsAndKeys:
                    [NSNumber numberWithInt:SET1], @"well",
                    [NSNumber numberWithInt:SET2], @"great",
                    nil];
    NSLog(@"to see well: %@",[videoKeyOfTag objectForKey:[NSNumber numberWithInt:SET1]]);   

}

I expect to see well: well in the log but instead I see what I don’t want:

to see well: (null)

Starting with an int, how can I call objectForKey from an NSDictionary where the keys are NSNumbers?

(I eventually want to extract values from the NSDictionary with [sender tag] as the meta-key.)

Answer 1

If you want the numbers to be keys, you need to invert the order in the constructor:

videoKeyOfTag = [[NSDictionary alloc] initWithObjectsAndKeys:
                    @"well", [NSNumber numberWithInt:SET1], 
                    @"great", [NSNumber numberWithInt:SET2], 
                    nil];