Swift Basic Syntax III (functions and closures)

1 //Playground-noun:a Place where people can play2 3 ImportCocoa4 //functions and closures5 6 //function, declare the function using the Func keyword:7Func greet (name:string, day:string)String {8     return"Hello \ (name), today is \ (day)."9 }TenGreet ("Bob", "Tuesday") One  A  - //returning multiple values by tuple (tuple) -Func getgasprices ()(double, double, double) { the     return(3.59, 3.69, 3.79) - } - getgasprices () -  + //supports functions with variable-length parameters -Func sumof (Numbers:int ...)Int { +var sum = 0 A      forNumber in numbers { atSum + = Number -     } -     returnsum - } -  - sumof () inSumof (42, 597, 12) -  to //functions can also be nested +Func Returnfifteen ()Int { -var y = 10 the func Add () { *Y + = 5 $     }Panax Notoginseng Add () -     returny the } +  A Returnfifteen () the  + //as a first-class object, a function can either be a return value or be passed as a parameter -  $Func makeincrementer (), IntInt) { $Func AddOne (Number:int)Int { -         return1 + Number -     } the     returnAddOne - }Wuyivar increment =Makeincrementer () theIncrement (7) -  WuFunc hasanymatches (list:int[], Condition:int-Bool)Bool { -      foritem in list { About         ifcondition (item) { $             return true -         } -     } -     return false; A } +  theFunc Lessthanten (Number:int)Bool { -     returnNumber < 10 $ } thevar numbers = [20, 19, 7, 12] the hasanymatches (Numbers, Lessthanten) the  the //closures-essentially, a function is a special closure, and Swift can use {} to declare anonymous closures -  in Numbers.map ({ the(Number:int)Int in theLet result = 3 * Number About     returnresult the     }) the //when the type of closure is known, the following simplified notation can be used theNumbers.map ({number in 3 *Number }) + //parameters can also be used by the position of the parameter, and the following syntax can be used when the last parameter of the function is a closure: -Sort ([1, 5, 3, 2]) {$ > $}

Swift Basic Syntax III (functions and closures)