Swift Memory Management

Swift Memory Management

Priority: P0

Implementation Guidelines

ARC Fundamentals

• Default: Strong references. Swift automatically manages retain/release.
• Weak: Use weak if the reference can become nil during its lifetime (delegates, optional parent refs).
• Unowned: Use unowned if the reference is guaranteed to outlive the referring object (rare; prefer weak).

Capture Lists

• Closures: Place [weak self] at the beginning of the closure's capture list. Pattern: { [weak self] in guard let self = self else { return } }.
• Self in Structs: No capture list needed (self is copied by value).
• Multiple Captures: [weak self, weak delegate].

Retain Cycles

• Delegates: Always weak var delegate. The delegate protocol should inherit from AnyObject (e.g., protocol MyDelegate: AnyObject {}).
• Closures as Properties: Use weak or unowned in capture list.
• two-way References: One side must be weak.

Anti-Patterns

• No strong var delegate: Use weak.
• No self in escaping closures: Use [weak self].
• No unowned unless certain: Default to weak to prevent crashes.

References

• Capture Lists & Retain Cycles