A study of Swift language learning notes four-2 (some legacy of the previous section is processed)

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Some of the questions in the previous section have not been clarified, write it yourself, do a bit of verification, and hope to help the reader.

See Example:

The sample contains

Declaration and use of the callback function

Functions are passed as a form of participation

function as return value

Functions support generics, and of course class is supported.

Import Foundationtypealias point = (int, int.) Let Origin:point = (0, 0)//initialization function with Func Willdoit (Sender:callbackmanager) { println ("Willdoit defaulft.")} Func Diddoit (Sender:callbackmanager) {println ("Diddoit defaulft.")} Class callbackmanager{//declaration of two function variables var willdoitcallback: (Callbackmanager)---() = willdoit var Diddoitcallbac K: (Callbackmanager)-() = diddoit var callbackname = "Hello World" init () {} func TESTC All () {self.willdoitcallback (self) callbackname = "Reset Data" println ("to do something.") ) Self.diddoitcallback (self)}//function address as a form-pass func testparams (addfunc: (int,int)-(Int), Instru        ction:string)->bool {println ("3 + 5 = \ (Addfunc (3,5)), the second value is: \ (instruction)") return True} function as return value func Testfunctionreturn (instruction:string)-(int,int), Int {func multiplicatio           N (a:int,b:int)->int { Return a * b} return multiplication}//self-active closure type//Call Simpleassert (testnumber% 2 = = 0    , "Testnumber isn ' t an even number.") Func Simpleassert (Condition: @auto_closure (), Bool, message:string) {if!condition () {println (M    essage)}}//Variable parameter func unknowparam (slist:string ...)        {var ret:string = "" For USB in Slist {println (USB) RET + = (usb + ",")  }}//Using generic//simplemin (17, 42)//Integer parameters//simplemin (3.14159, 2.71828)///float func    Simplemin<t:comparable> (X:t, y:t), T {if x < y {return y} return x }}

Call:

Class Viewcontroller:uiviewcontroller {            func willcallback (Callback:callbackmanager)    {        println ("pre-callback result \ (Callback.callbackname)    }}        func Didcallback (Callback:callbackmanager)    {        println ("post-callback result \ ( callback.callbackname)    }        func Add (a:int,b:int), Int    {        return a + b    }    override Func Viewdidload () {        super.viewdidload ()        var test = Callbackmanager ()        test.willdoitcallback = Willcallback        test.diddoitcallback = Didcallback        test.testcall ()                test.testparams (add,instruction: "Test function as a reference") Let                funcmulti = Test.testfunctionreturn ("Return function address") let                ret = Funcmulti (5,5)        println ("5 * 5 = \ (ret)") 
   return;}}

A study of Swift language learning notes four-2 (some legacy of the previous section is processed)