.m File — Objective-C / MATLAB Source

The .m extension is shared by two major programming languages: Objective-C and MATLAB. In the Apple development context, .m files contain Objective-C source code — a superset of C that adds Smalltalk-style messaging and object-oriented features. Objective-C was the primary language for macOS and iOS development from the 1980s through 2014 when Swift was introduced. Objective-C's message-passing syntax ([object method:parameter]), dynamic runtime, categories, protocols, and ARC (Automatic Reference Counting) memory management are distinctive features. Legacy iOS/macOS codebases and system frameworks still contain substantial Objective-C code. In the scientific computing context, .m files contain MATLAB scripts and functions — MATLAB (Matrix Laboratory) is a proprietary numerical computing platform widely used in engineering, signal processing, control systems, and academic research. MATLAB's matrix-oriented syntax, extensive toolboxes, and Simulink integration make it essential for engineering workflows. GNU Octave provides an open-source, largely compatible alternative. Context (project type, imports) determines which language an .m file contains.