Objective-C ARC Patterns

Retain cycles occur when strong references create circular ownership. Use weak references for delegates and in block captures: declare properties with `__weak` or `weak` qualifiers, or capture `self` weakly in blocks using `__weak typeof(self) weakSelf = self;` to break the cycle and enable proper memory deallocation.

Strong references increase an object's retain count and keep it alive; weak references do not. Use strong for ownership and weak for back-references (delegates, observers) to avoid cycles. ARC automatically manages both, but incorrect qualification causes leaks or premature deallocation.

Use bridging casts with ownership semantics: `(__bridge)` for zero-cost casts, `(__bridge_retained)` when passing to Core Foundation (transfers retain), and `(__bridge_transfer)` when receiving from Core Foundation. Incorrect bridging causes memory leaks or crashes due to mismatched retain counts.

Yes, but capture `self` carefully. In dispatch blocks and async callbacks, capture `self` weakly to avoid retain cycles: convert to a strong reference inside the block only if needed. This prevents blocks from keeping the object alive longer than intended.

Delegate properties often create retain cycles if declared strong. The owner retains the delegate, and the delegate retains the owner. Declare delegate properties as `weak` to break the cycle: `@property (nonatomic, weak) id<MyDelegate> delegate;`

Use `strong` for owned objects (default in ARC), `weak` for back-references and delegates, `copy` for immutable objects like NSString, and `assign` only for primitive types. Correct qualifiers prevent retain cycles and ensure predictable object lifetimes.