What are some common performance pitfalls in Swift and how to avoid them?

Common performance pitfalls in Swift and how to avoid them were discussed in the session Explore Swift performance. Here are some key points:

1. Inefficient Function Calls:

   • Pitfall: Making a lot of calls that aren't being optimized effectively.
   • Solution: Ensure that your function calls are optimized. Use whole module optimization to allow more inlining.

2. Memory Representation:

   • Pitfall: Wasting time or memory due to inefficient data representation.
   • Solution: Profile your code to identify expensive struct copies and ensure that your most copied structs have simple fields. Minimize the use of reference types, copy-on-write types, and Any.

3. Memory Allocation:

   • Pitfall: Spending too much time allocating memory.
   • Solution: Use tools to analyze heap memory and manage autorelease pool growth effectively. Enable whole module optimization to reduce overhead.

4. Value Copying:

   • Pitfall: Unnecessary copying and destroying of values.
   • Solution: Profile and look for generics that may need explicit specialization. Minimize the use of reference types and use non-copyable types where possible.

5. Automatic Reference Counting (ARC):

   • Pitfall: High overhead from retain and release calls.
   • Solution: Do not circumvent ARC. Instead, use tools to profile and reduce retain and release overhead. Mark methods as @objc_direct to allow inlining of Objective-C method calls and use objc_externally_retained attribute where applicable.

6. Generics and Protocols:

   • Pitfall: Inefficient use of generics and protocol types.
   • Solution: Profile your code to identify where explicit specialization of generics might be needed. Be mindful of the costs associated with using protocol types and use them judiciously.

For more detailed insights, you can refer to the session Explore Swift performance and Analyze heap memory.