What is the entry point of swift code execution? - Stack Overflow The entry point in a plain Swift module is the file in the module called main swift main swift is the only file which is allowed to have expressions and statements at the top level (all other Swift files in the module can only contain declarations) Cocoa Touch uses the @UIApplicationMain attribute on an implementation of UIApplicationDelegate instead of a main swift file to mark the entry
swift2 - Swift: guard let vs if let - Stack Overflow The Swift Docs on Control Flow explain the idea behind that: Using a guard statement for requirements improves the readability of your code, compared to doing the same check with an if statement