Swift's guard syntax is good, I admitted. But it's not always the best choice in some cases. Let's consider: something.callback() { someOther:SomeOther? in     guard let someOther = someOther else { return }     functionTakeSomeOther(someOther) } Indeed, "optional chaining" provide us a more convenience way to achieve the same goal with fewer

Map function is quite a convenience method that often used in functional(mainly) programming. In Swift, all collection types(Array,Dictionary,Set...) support map. It take a closure that take element type from T and output type U then transform from [T] to [U]. In most case, you will see