iOS Interview Question (Part 8)

_

1. What is an Autorelease Pool and What is Its Main Reason?
2. What is UUID and UDID.
3. Array vs Set
4. What is Codable
5. URLSession and types

What is an Autorelease Pool and What is Its Main Reason?

An Autorelease Pool is like a container used to manage memory for objects that are no longer needed but cannot be immediately deallocated.

• Temporary Storage Bin = Autorelease Pool
• Waste = Temporary objects (e.g., strings, arrays, etc.)
• Emptying the Bin = Draining the autorelease pool

How It Works:

• When an object is sent an autorelease message, it is added to the current autorelease pool.
• The autorelease pool keeps track of these objects and delays their deallocation until the pool itself is drained.
• When the autorelease pool is drained (typically at the end of a run loop iteration), it sends a release message to all the objects it holds, which may lead to their deallocation if their retain count drops to zero.

Why is it Useful?

• Prevents Memory Spikes: In loops or background tasks where many objects are created.
• Optimizes Memory Usage: Releases memory only when needed, improving performance.