Debugging in Xcode

Debugging in Xcode
Speaker: Hrishikesh Devhare

No developer 👨‍💻 is excited when someone comes to them with a list of bugs. 😒 But everyone has to 🔍debug the code. Let’s discuss hidden gems 💎in Xcode’s breakpoints, watchpoints and visual debugger and LLDB to squash those bugs 🔨and ship 🛳 your app. 😇

Talk Video: https://www.youtube.com/watch?v=fkoC0qyQnGg

Talk presented at Swift Mumbai Chapter 8 Meetup at Eros Now on April 13, 2019
https://www.meetup.com/Swift-Mumbai/events/259194853/

Twitter: https://twitter.com/hrishiD
Presented at Swift Mumbai Chapter 8 Meetup hosted by Eros Now
https://www.meetup.com/Swift-Mumbai/events/259194853/

Transcript

1. Debugging in Xcode Hrishikesh Devhare
3. Avoid Debugging
5. Avoid Debugging • Static Analyser • Run Time Tools • Assertions • Enums
6. Static Analyser
7. Finds following types of Bugs • Logic Flaws • Memory Management flaws • Dead Store • API Usage flaws Static Analyser
8. Static Analyser •Product -> Analyse • Issue Navigator
9. Static Analyser • Build Settings • Won’t cover all scenarios • Possibility of false positive • WWDC 2016 Session 412 
 Thread Sanitizer and Static Analysis
10. Run Time Tools
11. Run Time Tools
12. Run Time Tools
13. • Main Thread Sanitiser • Thread Sanitiser • Address Sanitiser • Undefined Behaviour Sanitiser Run Time Tools
14. Main Thread Sanitizer
15. Main Thread Sanitizer
16. • UI Updates on Main Thread • Creation and removal of UI Elements • Ready to use • WWDC 2017 Session 404
 Finding Bugs Using Xcode Runtime Tools Main Thread Sanitizer
17. Thread Sanitiser • Detects Data race • Threading bugs e.g. uninitialized mutexes and thread leaks • Use Dispatch API • WWDC 2016 Session 412 
 Thread Sanitizer and Static Analysis
18. Thread Sanitiser Limitations • Supported only for 64-bit macOS and 64-bit iOS and tvOS simulators. • watchOS is not supported • Can not use on when running apps on a device. • Performance Impact • increase in memory usage by 5⨉ to 10⨉ • CPU slowdown of 2⨉ to 20⨉
19. • Detects memory corruption • Use ARC • WWDC 2015 Session 413 
 Advanced Debugging and the Address Sanitizer Address Sanitiser
20. • Dividing by zero • Loading memory from a misaligned pointer • Dereferencing a null pointer • WWDC 2017 Session 404
 Finding Bugs Using Xcode Runtime Tools Undefined Behaviour Sanitiser
21. Swift Objective C Require 
 recompilation? Main Thread Sanitizer ✅ ✅ ❌ Thread Sanitizer ✅ ✅ ✅ Address Sanitizer ✅ ✅ ✅ Undefined Behaviour
 Sanitizer ❌ ✅ ✅ Run Time Tools
22. • Build Settings available for ASan & UBSan • https://developer.apple.com/documentation/ code_diagnostics Run Time Tools
23. Assertions
24. • Assert / Assert Failure • Pre conditions /Precondition Failures • Fatal Error Assertions
26. Enums
27. • Enums for finite states • Enums for string constants Enums
28. • State management • Network API • View Controller Navigation Enums for finite states
29. Enums for finite states ❌ ✅
30. Enums for Network API
31. Enums for Network API
32. Enums Meet Protocol
33. Navigation using Enum
34. • UserDefaults • Image • Notifications • Storyboard / XIB files • Dictionary keys • Bundle resources Enums for string constants
35. Enums for string constants
37. Recap ✅ Use Static Analyser ✅ Runtime tools for debug, test configuration. ✅ Asserts to validate app data state. ✅ Use Enums.
38. Discussion %
41. Speed up debugging • Break points • Watchpoints • LLDB • Visual Debugging
42. Thank you