SonarSource delivers what is probably the best static code analyzer you can find for Objective-C. It uses the most advanced techniques (pattern matching, dataflow analysis) to analyze code and find Code Smells, Bugs, and Security Vulnerabilities. As with everything we develop at SonarSource, it was built on the principles of depth, accuracy, and speed.
SonarSource's Objective-C analysis has a great coverage of well-established quality standards. This is available in any development chain for automated code review with self-hosted SonarQube or cloud-based SonarCloud.
SonarSource's Objective-C analysis supports all the standard metrics implemented by SonarQube including Cognitive Complexity. Additionally, it supports the import of LLVM-cov Coverage reports.
SonarSource's Objective-C analysis doesn't yet provide the ability to write custom rules.