Automated Static Analysis
Several automated tools for analyzing iOS apps are available; most of them are commercial tools. The free and open source tools MobSF and objection have some static and dynamic analysis functionality. Additional tools are listed in the "Static Source Code Analysis" section of the Testing Tools chapter.
Don't shy away from using automated scanners for your analysis - they help you pick low-hanging fruit and allow you to focus on the more interesting aspects of analysis, such as the business logic. Keep in mind that static analyzers may produce false positives and false negatives; always review the findings carefully.