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

Posted by Renan A
Renan A
4,425 Points

Assigning object from an array inside a dictionary

I don't know what's wrong here

variable_assignment.mm 
NSArray *shoeOrder = @[@"Charles Smith", @9.5, @"loafer", @"brown"];

NSMutableDictionary *shoeOrderDict = [[NSMutableDictionary alloc]initWithObjectsAndKeys:
                                      @[shoeOrder objectAtIndex:0]: @"customer",
                                      @[shoeOrder objectAtIndex:1]: @"size",
                                      @[shoeOrder objectAtIndex:2]: @"style",
                                      @[shoeOrder objectAtIndex:3]: @"color"];
/*shoeOrderDict = {
                @"customer": [shoeOrder objectAtIndex:0],
                @"size": [shoeOrder objectAtIndex:1],
                @"style": [shoeOrder objectAtIndex:2],
                @"color": [shoeOrder objectAtIndex:3]
};
/*

1 Answer

Anjali Pasupathy
Anjali Pasupathy
28,883 Points
Anjali Pasupathy
Anjali Pasupathy
28,883 Points

You're very close. You just have a few syntax errors.

Firstly, when using initWithObjectsAndKeys, every object and key is separated by a comma, not a colon. You need to remove all those colons between the objects and their respective keys, and replace them with commas.

You also need to put a nil value after the last key to let the compiler know that you've finished adding objects and keys to the dictionary in your init method.

Lastly, you need to get rid of each "@" in front of the objects you're getting from the shoeOrder array. [shoeOrder objectAtIndex: INSERT INDEX HERE] is a method that returns an object from the shoeOrder array at the specified index. It isn't a literal value, so it doesn't need those "@" symbols in front of them.

NSMutableDictionary *shoeOrderDict = [[NSMutableDictionary alloc]initWithObjectsAndKeys:
                                      [shoeOrder objectAtIndex:0], @"customer",
                                      [shoeOrder objectAtIndex:1], @"size",
                                      [shoeOrder objectAtIndex:2], @"style",
                                      [shoeOrder objectAtIndex:3], @"color",
                                      nil];

I hope this helps!