Array of functions in Swift

Question

How can I store an array of functions to callback later in an array like in JavaScript? Any and AnyObject type cannot hold functions with different types of method signatures.

Answer 1

You can use an enum to put various functions into the Array and then extract the functions with a switch.

    enum MyFuncs {         case Arity0 ( Void -> Void )         case Arity2 ( (Int, String) -> Void)     }      func someFunc(n:Int, S:String) { }     func boringFunc() {}     var funcs = Array<MyFuncs>()     funcs.append(MyFuncs.Arity0(boringFunc))     funcs.append( MyFuncs.Arity2(someFunc))      for f in funcs {         switch f {         case let .Arity0(f):             f()  // call the function with no arguments         case let .Arity2(f):             f(2,"fred") // call the function with two args         }     } 

Answer 2

Note: this answer is for Swift versions 1.0 and lower.

Functions that have different parameters and return types are of a different type so they can't be stored in an array together. They also don't conform to the Any or AnyObject protocols.

If you have functions with the same parameters though you can work around that. Even though the functions below return a tuple of Double and an Int, they can both be defined as () -> Any function types.

func func1 () -> Int {     return 1 } func func2 () -> (Double, Double){     return (2, 3) } var a: () -> Int = func1 var b: () -> (Double, Double) = func2  var arr: Array< () -> Any> = [a, b]