SwiftLint was developed by the nice folks @realm. It's a great open-source tool for establishing and enforcing a formal coding style in Swift. It runs on the command-line, but it can be hooked into Xcode directly too. It also boasts an "autocorrect" feature, which sweeps through your code and automatically fixes the most trivial violations (e.g., colon positioning, double white spaces, etc.). I created a Git commit hook which does exactly this, every time a team member makes changes.
Can't believe we're still dealing with this in 2017? Well, that makes two of us. While retain cycles are easy to fix, they're also hard to spot while eyeballing a codebase. Recently, I've found that a single unit test can provide solace. With just a few lines of code, it runs continuously as you make changes, all the while verifying you haven't introduced any new memory leaks.