Memory efficiency of three properties compared to one NSDictionary

Question

I want to pass some data to my object and there are two options for me.

Regarding memory - what's more effecient? To declare three properties or to to declare one NSDictionary using initWithCapacity:3?

Answer 1

Declaring 3 properties will use less memory and be more performant than using an NSMutableDictionary.

Using properties also makes your code easier to read and allows your compiler to help you with type-safety.

Another consideration, is that you can't store nil in a collection.

EDIT:

As far as memory is concerned, the only difference between the 2 options that you mentioned is that the NSDictionary requires its own memory in the heap. The objects themselves will still require the same memory in the heap either way.

Answer 2

I would advocate for using properties, but not because of a performance issue; simply because I think it's more readable and less error-prone—you can make the dictionary approach clean by using key constants, but it's extra work.

The bottom line here, for me, is that until Instruments shows you that you're spending a significant amount of time or memory on these objects, you should take the path of readability and clarity. It's highly unlikely that it's going to matter if you shave a few cycles or a few bytes. But even if it does, it's not going to be a huge job to refactor the approach you take for an object initialization of three parameters.