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iOS Object-Oriented Objective-C Memory, Arrays and Loops, Oh My! Review Dictionaries and Arrays

Amir Bahadori
Amir Bahadori
5,498 Points
Posted by Amir Bahadori
Amir Bahadori
5,498 Points

Dictionaries and Arrays Challenge Task 3 of 3: Help needed on task 3

Now add the values in our array to our new dictionary. The keys for the values should be: 'customer', 'size', 'style' and 'color'. The values in the original array are in the same order as the keys listed above. (Note: Don't set the values directly as strings, but rather use something like 'objectAtIndex' to reference the original array.)

NSArray *shoeOrder = @[ @"Charles Smith", @(9.5), @"loafer", @"brown"]; NSMutableDictionary *shoeOrderDict = [[NSMutableDictionary alloc] initWithObjectsAndKeys: nil];

variable_assignment.mm 
NSArray *shoeOrder = @[ @"Charles Smith", @(9.5), @"loafer", @"brown"];
NSMutableDictionary *shoeOrderDict = [[NSMutableDictionary alloc] initWithObjectsAndKeys: nil];

1 Answer

Steve Hunter
Steve Hunter
57,712 Points

Hi Amir,

You've got the array set up, so you now need to populate the dictionary with the contents of that array, and the keys given in the question.

You can do this one step at a time, using each key in turn using literal syntax. So, once you've you've declared the dictionary, with alloc and init, you can use that variable name and add each new key and assign the value from the array, one element at a time.

That looks like:

NSArray *shoeOrder = @[@"Charles Smith", @(9.5), @"loafer", @"brown"];
NSMutableDictionary *shoeOrderDict= [[NSMutableDictionary alloc] init];
shoeOrderDict[@"customer"] = [shoeOrder objectAtIndex: 0];
shoeOrderDict[@"size"] = [shoeOrder objectAtIndex: 1];
shoeOrderDict[@"style"] = [shoeOrder objectAtIndex: 2];
shoeOrderDict[@"color"] = [shoeOrder objectAtIndex: 3];

I hope that helps,

Steve.

Steve Hunter
Steve Hunter
57,712 Points

I guess you could also use something like:

[shoeOrderDict setValue:[shoeOrder objectAtIndex:0] forKey:@"customer"];

I'm not sure that adds any clarity or advantage - but it looks OK to me.

Amir Bahadori
Amir Bahadori
5,498 Points
Amir Bahadori
Amir Bahadori
5,498 Points

Thanks Steve, I looked around to find the syntax to add an object from an existing array into a mutable dictionary and couldn't find anything. Appreciate it.