How to Play LLDB in iOS runtime?

Transcript

1. How to play with LLDB in iOS runtime? @stinge
2. • slide url
 https://ppt.cc/fhdtqx • QR Code
3. Background stinge • Mercari iOS Engineer • twitter: @StingeSu • hobby: traveling & cooking
4. Outline • Why LLDB(Low Level Debugger)? • How LLDB works? • LLDB OSS • Custom LLDB command
5. Why LLDB? • high-performance debugger • Clang expression parser & LLVM disassembler • Default debugger in Xcode • Run Swift REPL & python supported • Save your time
6. Clang v.s GCC(GNU Compiler Collection) Clang • Apple official compiler • Frontend for LLVM • High performance • BSD license • …… GCC • Linux based • Support more languages • GPL license
7. Clang (Xcode 10.2.1) GCC (Darwin Kernel on Raspberry Pi)
8. • How Apple deprecated GCC Front-end Back-end Xcode 3 GCC GCC Xcode 4 GCC LLVM Xcode 5 Clang LLVM
9. • gcc hello.c
10. Is it good for iOS?
11. Is it good for iOS? NO 
12. build process
13. Clang-Swift • The compiler process of swift cmd+B
14. Clang-Swift • The compiler process of swift Clang AST Reference https://ppt.cc/fnA4Qx
15. Clang-Swift • The compiler process of swift
16. How LLDB works?
17. How LLDB works? command action option argument
19. • p(print) → expr -- expr -- foo • po(print object) → expr -O -- expr -O -- foo
20. p v.s po
22. • Changes the value of variables • Creates temporary variables • Validates the values
23. • DEMO • Tasks 1. Changes UIButton title into red 2. Moves UIView up
24. • Can we use a efficient way to finish these commands?
 - YES
25. LLDB Python API https://lldb.llvm.org/python_reference/index.html
26. LLDB OSS • Facebook/chisel • DEMO
27. Customized command • nudge(swift) • DEMO https://gist.github.com/sTinGe/059dc4c15347b7fef4ee537efdcc6e53