Hands-On Design Patterns with Swift

Closures, functions, and currying

Closures are blocks of code that can be executed later, and functions are a special case of closures. Functions and closures can be passed around in your code, returned by other functions or closures. You can store a closure or a function in a variable, and execute them later:

let runMe = { () -> Int in    print(“run”)    return 0}runMe()

The preceding code is equivalent to the following:

func runMe() -> Int {    print(“run”)    return 0}runMe()

Closures and functions are almost always interchangeable, except when it comes to class or struct members:

class MyClass  {    var running = false    lazy var runWithClosure: () -> Void = {        self.running = true    }    func runWithFunction() {        self.running = true    }}

While both implementations ...