Question

If I have a large NSDirectory typically from a parsed JSON-object I can access this object with code like so:

[[[[[obj objectForKey:@"root"] objectForKey:@"key1"] objectAtIndex:idx] objectForKey:@"key2"] objectAtIndex:idz];

The line might be a lot longer than this.

Can I optimize this code in any way? At least make it easier to read?

This line will also generate a runtime-error if the object does not correspond, what is the most efficient way to avoid that?

Answer 1

If you were using -objectForKey: for everything you could use -valueForKeyPath:, as in

[obj valueForKeyPath:@"key1.key2.key3.key4"]

However, this doesn’t work when you need to use -objectAtIndex:. I don’t think there’s any good solution for you. -valueForKeyPath: also wouldn’t solve the problem of the runtime errors.

If you truly want a simple way to do this you could write your own version of -valueForKeyPath: (call it something else) that provides a syntax for specifying an -objectAtIndex: instead of a key, and that does the appropriate dynamic checks to ensure the object actually responds to the method in question.