Understanding Objective‑C Object Memory Layout and Alignment
This article explores how Objective‑C objects are converted to low‑level C/C++ structures, compares the results of class_getInstanceSize, malloc_size and sizeof, and explains memory‑alignment rules, member ordering, padding, and inheritance effects on the actual memory footprint of iOS objects.
The article explains how Objective‑C objects are transformed into C/C++ structures, examines APIs such as class_getInstanceSize, malloc_size and the sizeof operator to measure object size, and details the rules of memory alignment on 64‑bit iOS.
It provides step‑by‑step examples, including clang command output and struct definitions for NSObject_IMPL and custom classes, and demonstrates how member order, padding, and inheritance affect the final allocated size, with visual diagrams and reference links.
Signed-in readers can open the original source through BestHub's protected redirect.
This article has been distilled and summarized from source material, then republished for learning and reference. If you believe it infringes your rights, please contactand we will review it promptly.
Sohu Tech Products
A knowledge-sharing platform for Sohu's technology products. As a leading Chinese internet brand with media, video, search, and gaming services and over 700 million users, Sohu continuously drives tech innovation and practice. We’ll share practical insights and tech news here.
How this landed with the community
Was this worth your time?
0 Comments
Thoughtful readers leave field notes, pushback, and hard-won operational detail here.