How does Mach-O binary loading work in iOS apps at a high level?

Mach-O binaries are loaded by dyld which maps segments, resolves symbols, and initializes runtime components.

When an iOS app launches, the kernel loads the Mach-O executable into memory. dyld (dynamic linker) then maps segments like __TEXT, __DATA, and __LINKEDIT. It resolves external symbols, binds dynamic libraries, and triggers Objective-C runtime setup. The runtime registers classes, categories, and executes +load methods before main(). This pipeline is critical for app startup performance.