iOS pluralization is powerful, flexible—and notoriously easy to get wrong. Instead of a simple plural resource type, iOS relies on .stringsdict files that combine plural rules, formatting logic, and variable substitution. The syntax is verbose, the failure modes are subtle, and many mistakes don’t appear until you add multiple languages. Missing plural categories can cause incorrect fallbacks or even return raw keys instead of strings, while placeholder specifiers like %d or %@ can drift during translation and trigger runtime formatting errors. This guide walks through how .stringsdict files are evaluated, the most common traps teams fall into, and how to structure plural logic defensively. The goal is to make pluralization predictable and safe, even as your app scales to more languages and contributors.