Swift Chapter Fourth: Closures, UI basics, Protocol

First of all, the closure of the packet, in fact, the closures and the previous block callback function in c similar, but here only to study the use of the basic, I in the following two VC use closure to do the communication value, is also a more commonly used method bar, I have time to look back on the project in other applications

 let sayhello = {    println ("Nihao")}sayhello ()//define a closure function, Unlike conventional methods, there is a keyword in the let add = {  (a: int, b: int)  -> int in The     return a + b}//call is actually the same as invoking the method Oh println (Add (1, 2))//The following is a simple example, To find a value greater than or equal to value in the array, and if so, return Yesvar array = [20, 9, 100, 34, 89, 39]func  hasclosurematch (array: [int], value: int, closurevalue:  (Num:Int, value:I NT)-> bool)-> bool {    for item in array {         if  (Closurevalue (num: item, value: value))   {            return true         }    }    return false}//closure   Closed Bag Var v1 = hasClosurematch (array, 40)  {  (num, value)  -> Bool in     return num >= value}println (v1)

Then there is the UI-based code that can directly create a single controller project, primarily to familiarize yourself with the code

Here we can first turn off the storyboard, directly change the method inside the Appdelegate

UI here there is not much to talk about, mainly to check the relevant API, and then slowly accumulate

 func application (application: uiapplication, didfinishlaunchingwithoptions  Launchoptions: [nsobject: anyobject]?)  -> Bool {        // Override point  for customization after application launch.         self.window = uiwindow (Frame: uiscreen.mainscreen (). Bounds)          self.window!. Backgroundcolor = uicolor.whitecolor ()         self.window!. Makekeyandvisible ()                  //from grammar, I think with o-c really very different, but the truth is through, if your o-c language is still skilled, I want to get started Swift language is also very easy          let rootviewcontroller = rootviewcontroller ()          let navigationcontroller = uinavigationcoNtroller (Rootviewcontroller: rootviewcontroller)          Navigationcontroller.tabbaritem = uitabbaritem (title:  "First page",  image: nil, tag:  1)                 let  secondviewcontroller = secondviewcontroller ()          Let secondnavigationcontroller = uinavigationcontroller (rootviewcontroller:  Secondviewcontroller)         secondnavigationcontroller.tabbaritem  = uitabbaritem (title:  "second page",  image: nil, tag: 2)                  let array = [ Navigationcontroller, secondnavigationcontroller];        let  tabbarcontroller = uitabbarcontroller ()         tabbarcontroller.viewcontrollers = array                 self.window!. rootviewcontroller = tabbarcontroller                 return true    }

Next we create two VC classes, Swift does not have the so-called designated class creation, but in the swift file, we can create a lot of many classes, of course, for a better distinction, I would like to create a separate class bar

So we create some basic controls in two classes, and then write a protocol to use it.

It's mostly about getting to know the grammar.

In the following code also used in protocol and closure, easy for small partners to get started OH

 class RootViewController: UIViewController, ViewChangeDelegate {     var clickCount:Int = 0;    var myLabel:UILabel?         override func viewdidload ()  {         super.viewdidload ()                  self.title =  "Furnace stone legend"                  let nextitem = uibarbuttonitem (title:  "Next page",  style: . plain, target: self, action:  "NextPage:")          self.navigationitem.rightbarbuttonitem = nextitem                 mylabel = uilabel (Frame: CGRect (x: 0,  y: 100, width: 320, height: 44))         mylabel!. text =  "Xiao Hua, hello"         mylabel!. Backgroundcolor = uicolor.redcolor ()          Self.view.addSubview (mylabel!)                 var  Mybutton = uibutton (Frame: cgrect (x: 100, y: 200, width: 100,  height: 44))         myButton.backgroundColor =  Uicolor.bluecolor ()         mybutton.settitle ("Click",  forState:  . Normal)         mybutton.addtarget (self, action:  "ClickMe:",  forcontrolevents: . Touchupinside)         self.view.addsubview (MyButton)      } &Nbsp;      func clickme (Sender:uibutton)  {         clickcount += 1;        println (" Click\ (Clickcount) ")         mylabel!. text =  "You guess I ordered a few times, \ (clickcount)"     }         func nextpage (Sender:uibutton)  {        let  Secondviewcontroller = secondviewcontroller ()          secondviewcontroller.viewchangedelegate = self         Secondviewcontroller.changetextforclosure ("1",  num: 1)  {  (value, num)  ->  void in            mylabel?. Text = value        }  &nbSp;     self.navigationcontroller?. Pushviewcontroller (secondviewcontroller, animated: true)     }         func changetitletostring (controller:uiviewcontroller, value:string)  {        mylabel!. text = value    }

 import foundationimport uikitclass secondviewcontroller: uiviewcontroller {     var viewChangeDelegate:ViewChangeDelegate?    var  closure = {  (Value:string, num:int)  -> Void in             }        override  func viewdidload ()  {        super.viewdidload ()                  self.title =   "second page"         self.view.backgroundColor =  Uicolor.graycolor ()                  var button = uibutton.buttonwithtype (. System)  as! UIButton        button.frame = cgrect (x: 100, y: 100, width: 100, height: 40)          button.settitle ("Return to Previous Page",  forstate: .) Normal)         button.addtarget (self, action:  "Back:",  forcontrolevents: . touchupinside)         self.view.addsubview (button)                  var buttonchange =  uibutton.buttonwithtype (. System)  as! UIButton        buttonChange.frame =  CGRect (x: 100, y: 200, width: 100, height: 40)          buttonchange.settitle ("Change Home label value",  forstate: . Normal)         buttonchange.addtarget (self, action:  "Change: ",  forcontrolevents: . ToUchupinside)         self.view.addsubview (buttonChange)      }        func changetextforclosure (Value:String,  num:int, closurevalue: (value:string, num:int)  -> void)  {         self.closure = closureValue    }         func change (Sender:uibutton)  {         if  ((viewchangedelegate)  != nil)  {             viewchangedelegate?. Changetitletostring (self, value:  "I Change to change")         }         self.closure ("Hello",  1)     }         func back (Sender:uibutton)  {         self.navigationcontroller?. Poptorootviewcontrolleranimated (True)     }}protocol ViewChangeDelegate :  Nsobjectprotocol {    func changetitletostring (Controller:UIViewController,  value:string)}

All right, let's just write this a lot.

This article is from the "Neusoft iOS Alumni Group Technology Blog" blog, please be sure to keep this source http://neusoftios.blog.51cto.com/9977509/1674151

Swift Chapter Fourth: Closures, UI basics, Protocol