"Swift-Summary" closure

Actually, closures are functions.
function as a condition

Closed-Packet expression

First declare an array

var names = ["Charis""Alex""Ewa""Barry""Daniella"]

Sort this array alphabetically

Declaring a closed-packet function

func backwards(s1: String, s2:String) -> Bool  {    return s1 > s2}

The sorted () function returns an array, and the sort () function returns NULL, sorting itself

///传入闭包函数names.sort(backwards)

Using a closure expression

//闭包表达式就是一个函数在花括号里面names.StringString-> inreturn> s2})

And because the value of Swift is an inferred type

The above can also be simplified

varinreturn s1 > s2})

Single-closed Baoyin return

//会隐式returnin s1 > s2})

Name abbreviation

names.sort({$0$1})

operator functions

names.sort(>)

Trailing closures

Sometimes closure expressions are too cumbersome to write closures in curly braces that follow the calling function.

//调用sort函数，后面添加花括号，然后闭包表达式就写在这里names.sort() {$0$1}

Official examples

//Declare a dictionary LetDigitnames = [0:"Zero",1:"One",2:"both",3:"three",4:"Four",5:"Five",6:"Six",7:"Seven",8:"Eight",9:"Nine"]//An array Letnumbers = [ -, -,510]//Call the map function with the incoming closure inside Letstrings = numbers.map{//Pass in a number to return a string(varNumber)String inch    varOutput =""     whileNumber >0{output = digitnames[number%Ten]! + Output//find each number and convert to a stringNumber/=Ten}returnOutput

Value capture

first the closure is the reference type
Official examples

///defines a function that returns () type Int ()  Func makeincrementor (forincrement amount:int) ->  () - >  Int {var  runningtotal =  0  //a closure function  func incrementor () ->         Int {runningtotal +=  amount; return  runningtotal} //return this closure, At this point the closure already contains the value of RunningTotal and amount  return  incrementor}  

let10)let1)incrementByTen1()   //10 所以值会被闭包一直保留incrementByTen1()   //20incrementByTen2()   //1

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"Swift-Summary" closure