ArraySlice Doesn't Give You a Piece of the Array. It Gives the Whole Array a Reason to Stay Alive.
ArraySlice and Substring look like lightweight, independent copies of part of a collection, but they hold a reference to the entire original storage. Here's the real memory-retention bug that causes, and how ~Escapable and Span are about to make it a compile-time guarantee instead of a docs warning.
NSCache Looks Like a Dictionary With a Size Limit. It Isn't Promising You That.
NSCache's countLimit and totalCostLimit read like hard caps, but Apple's docs never promise them as guarantees, and eviction can happen for reasons you can't predict. Here's what NSCache actually contracts to do — and the one gotcha that breaks lookups silently.
Weak Self Isn't the Retain Cycle Fix You Think It Is in @Observable
The old [weak self] advice was written for closures capturing classes. @Observable changes what actually gets captured, and in a few common SwiftUI patterns weak self silently does nothing at all. Here's where it still matters and where it's dead weight.