1. To maintain high quality iOS code, one should follow a code style, generate code using tools, and use static analysis tools to find problems and issues. 2. Key tools include Clang-Format for code style, Xcode for code generation, and OCLint and SwiftLint for static analysis to find defects, bad practices, and code smells. 3. After analyzing code using tools, one should refactor code to clean up any issues found and then cover all code with unit tests.

1. Be armed to the teeth
to maintain a high quality iOS code
Anastasia Kazakova

2. Program vs Product
• ACM-ICPC: Solve quicker than others, pass tests, start another task.
• Real word: How often do you rewrite the project from scratch?

3. What is code quality?
Some say:
Easy to understand
Easy to maintain
Easy to use
Works right
Some say:
high quality == meets
requirements
Some say (CISQ):
Reliability
Efficiency
Security
Maintainability
Size

4. What is code quality?

5. WTFs/minute metric

6. Have you ever encountered this?

7. … or this …

8. …or this?

9. GOTO FAIL?

10. Possible problems
• Dead code
• Copy/paste,
duplicated code
• Hiding scope
• Too much happening
at one place
• Code style
inconsistency
• Patterns violations
• Bad coding practices
• Over-generalized code
• …

11. What do we have to do?
1. Follow the code style
2. Generate code
3. Run static analysis
4. Refactor
5. Run unit tests

12. "We need tools”
Bjarne Stroustrup at CppCon2015

13. Armed to the teeth #1:
Code style
• Apple’s coding guidelines for Cocoa
• raywenderlich.com:
• https://github.com/raywenderlich/objective-c-style-guide
• https://github.com/raywenderlich/swift-style-guide
• GitHub:
• https://github.com/github/objective-c-style-guide
• https://github.com/github/swift-style-guide
• Spotify
• https://github.com/spotify/ios-style

14. Armed to the teeth #1:
Code style
Clang-Format:
• Stand-alone, tools integration.
• Plugin for Xcode: https://github.com/travisjeffery/ClangFormat-
Xcode with option to enable format on save.
• Indents, braces, breaks, line length, base styles, aligns, and much
more.
• Objective-C, no Swift :(

15. Armed to the teeth #1:
Code style
Clang-Format

16. Armed to the teeth #1:
Code style
• Pre-commit hooks: ocstyle, SwiftFormat, SpaceCommander (uses
Clang-Format) & more on GitHub.
• Some check in SwiftLint

17. Armed to the teeth #1:
Code style
AppCode
• Settings for
Objective-C, C, C+
+, Swift.
• Reformat action
• On-the-fly
• Format on commit
stage

18. Armed to the teeth #2:
Generate code
• Xcode pre-generates some methods when creating files/classes.
• Xcode code snippets for Objective-C and Swift.
• Override/Implement code generation on completion in Xcode.
• There were some 3d-party tools like xobjc on GitHub.

19. Armed to the teeth #2:
Generate code
AppCode:
• Generate menu
• Live Templates
• Create from usage
• Override/Implement
• File Templates

20. Armed to the teeth #3:
Static analysis
Tools:
• Guidelines/rules
• Configuration settings
• On-the-fly mode
• Quick fixes

21. Armed to the teeth #3:
Static analysis
Clang analyzer:
• Open source, part of Clang project
• Integrated into Xcode
• Basic checks, dead code, API checks, language specific checks
But don’t forget to switch them all on!

22. Armed to the teeth #3:
Static analysis
OCLint: https://github.com/oclint
• Metric-based defects:
• complicated code;
• redundant code;
• long methods, long parameters lists, etc.;
• bad practices (like parameter reassignment).
• 58 rules that can be customized per project
• Integrated with clang analyzer
• Can be used inside the Xcode

23. Armed to the teeth #3:
Static analysis
SwiftLint: https://github.com/realm/SwiftLint
• Similar to OCLint
• Limited in number of rules, planned rules:
• Code style checks (spaces, newlines);
• let over var rule; struct over classes;
• Working with optionals (like not forcing unwrapping);
• Specify access control and more.
• Contribute!

24. Armed to the teeth #3:
Static analysis
OCLint and SwiftLint

25. Armed to the teeth #3:
Static analysis
OCLint and SwiftLint

26. Armed to the teeth #3:
Static analysis
AppCode
• Integrated with clang
analyzer
• 60 inspections for
Objective-C, 40 for C/
C++, on-the-fly mode
• Settings, severity level,
profiles

27. Armed to the teeth #3:
Static analysis
AppCode: complicated cases, bulk mode

28. Armed to the teeth #3:
Static analysis
AppCode: quick fixes, DFA

29. Armed to the teeth #3:
Static analysis
AppCode:
Checks on commit
stage
• formatter
• code analysis
• TODO
• imports

30. Armed to the teeth #4:
Refactoring
• Xcode refactorings
• Rename, Extract (method/function), Move up/down, Create superclass, Encapsulate,
Convert…
• C and Objective-C only
• AppCode refactorings
• + Inline, Safe delete, Change signature, Extract everything, Rename with non-code
usages (strings, comment, xib, etc.) for Objective-C, C, C++
• Rename in Swift
• Some projects on GitHub, like Refactorial

31. Armed to the teeth #5:
Unit testing
• XCTest
• Kiwi: BDD framework for Objective-C
• Google Test: tests for C/C++
• Specta/Expecta: TDD / BDD framework for Objective-C
• Quick/Nimble: Swift BDD framework

32. Armed to the teeth #5:
Unit testing
AppCode: unit tests code generation

33. Summary
TODO:
• Follow selected code style
• Generate standard pieces of code
• Use the swiss-army knife thoughtfully
to find smells
• Refactor to clean up the smells
• Cover every inch with the unit tests
Tools:
• Xcode
• Clang-Format
• OC/Swift-Lint
• AppCode

34. Thanks for listening!
Anastasia.Kazakova@jetbrains.com
@anastasiak2512
IDE for iOS/OS X dev: http://jetbrains.com/appcode, @appcode