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

Posted by Michael S
Michael S
3,348 Points

Can you please let me know where the error is with my code?

The error message is saying that at least one of my values/keys is mixed up.

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

NSMutableDictionary *shoeOrderDict = [[NSMutableDictionary alloc]init]; 

    shoeOrderDict = [NSMutableDictionary dictionaryWithObject:[shoeOrder objectAtIndex:0] forKey:@"customer"];
    shoeOrderDict = [NSMutableDictionary dictionaryWithObject:[shoeOrder objectAtIndex:1] forKey:@"size"];
    shoeOrderDict = [NSMutableDictionary dictionaryWithObject:[shoeOrder objectAtIndex:2] forKey:@"style"];
    shoeOrderDict = [NSMutableDictionary dictionaryWithObject:[shoeOrder objectAtIndex:3] forKey:@"color"];

1 Answer

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

The dictionaryWithObject:forKey: method is a convenience method for allocating and initializing a dictionary, not for adding key-value pairs to a dictionary. Your code, as it stands, essentially allocates and initializes a new dictionary and assigns that dictionary to shoeOrderDict with each line of code, rather than adding a key-value pair for each line of code.

The method you want to use is the setValue:forKey method, and is implemented as follows:

[shoeOrderDict setValue: /*INSERT OBJECT HERE*/ forKey: /*INSERT KEY HERE*/];

I hope this helps!