Looping through values in NSDictionary throws fault

Question

I have a plist file that I am loading into an NSDictionary *setDictionary that contains a set of fields, pictureDesc1, pictureDesc2, etc.

Once the NSDictionary is loaded, I can retrieve a value using

[setDictionary objectForKey:@"pictureDesc1"];

But I cannot do a loop like this:

for (int i=1; i<=numberOfPictures; i++) {
    NSString *keyName = [NSString stringWithFormat:@"pictureDesc%d",i];
    NSString *description = [NSString stringWithFormat:@"%@", [setDictionary objectForKey:keyName]];
}

Is there a different way to dynamically call keys from within an NSDictionary?

Answer 1

If you keys fit a numerical pattern, then it would be easier and more robust to simply store them in a array. You could even store an array as a value in the dictionary with the key of "pictureDescription".

Then when you wanted to loop through them just use a simple numerical loop:

NSArray *pictArray=[setDictionary valueForKey:@"pictureDescription"];
NSString *description;
for (i=0;i<[pictArray count];i++){
    description=[pictArray objectAtIndex:i];
    //... do whatever
}

If you find yourself shoehorning the functionality of an array into a dictionary or vice versa you probably should back out and just use an array or dictionary in the first place. When using a dictionary, just use an enumerator to step through the values.