Expected method to read dictionary element not found on object of type "class"

Question

I'm trying to implement keyed subscripting for a custom class in Objective-C:

This is what I have in the header:

- (id)objectAtKeyedSubscript:(id <NSCopying>)key;

And this is what I have in the implementation:

- (id)objectAtKeyedSubscript:(id <NSCopying>)key
{
    id result = self.attributes[key];
    return result;  
}

I use it like so:

element[@"href"];

where before I did:

[element objectForKey:@"href"];

where objectForKey was being implemented like so:

- (NSString *) objectForKey:(NSString *) theKey
{
    return [[self attributes] objectForKey:theKey];
}

Something I'm missing? Doing wrong?

Answer 1

The name of the method is objectForKeyedSubscript:, not objectAtKeyedSubscript:.

Answer 2

Despite a lot of appearances of the name "objectAtKeyedSubscript:" out there on the web, the correct method name is objectForKeyedSubscript:

Notice that this parallels the non-subscript method name objectForKey:, as objectAtIndexedSubscript: does objectAtIndex: