CODEWITHSUNDEEP
iosobjective-cperformance
Aamir
Aamir

Reputation: 16957

Is there any way to check Time Complexity of methods provided by Objective-c?

Actually sometimes you are required to write some custom code to achieve some functionality, there would be 2 possible approaches there:

  1. make your implementation by joining already given methods of Objective-c
  2. write your custom code

At that point I am confused which code base is better(in performance), that can only be decided if I luckily find Time-Complexity of Objective-c methods. So is there any way to know about it?

Upvotes: 2

Views: 781

Answers (1)

rickster
rickster

Reputation: 126127

There are a lot of methods and functions you can call in the SDKs for iOS (and other Apple platforms), so this question is perhaps excessively broad.

But a discussion of time complexity is usually about algorithmic complexity, so we can restrict our scope to those calls that are the building blocks of algorithms where we measure time as a function of input size — that is, things like collection operations rather than, say, UIApplication registerForRemoteNotifications.

By and large, however, Apple doesn't talk much about the computational complexity of the high-level data structures in Cocoa. This probably has something do with Cocoa's design goals being strongly in favor of encapsulation, with simple interfaces hiding powerful, dynamic, and possibly adaptable implementations. Examining CoreFoundation — the open source implementations underlying the central bits of Cocoa, like collections — bears this out. Here's a great writeup on how NSArray is sometimes O(1) and sometimes not.

There's certainly something to be said for a philosophy where you're not supposed to care about the complexity of the tools you're using — tell it what you want to do, not how you want it done, and let it optimize performance for you, because it can second-guess you better than you can second-guess yourself. It goes well with a philosophy of avoiding premature optimization.

On the other hand, there's also some sense to a philosophy of having basic building blocks of enforced, predictable complexity so that you can more easily plan the complexity of the algorithms you build from them. Just to show that Apple seems to do it both ways, it appears this is the philosophy of choice for the Swift standard library.

Upvotes: 4

Related Questions