• 參考青玉伏案的博客

參考青玉伏案的博客--函數(shù)與閉包

函數(shù)

    var didRightButtonBlock:(()->())?

    func didClickRightButton(){
        didRightButtonBlock!()
    }

閉包weakself的寫法{ [weak self]  參數(shù) in
} 

init(block:()-> Void)

• 不定參數(shù)函數(shù)

func increatmultableAdd(numbers:Int ...) -> Int {
    var sumOfNumber: Int = 0
    for number in numbers {
        sumOfNumber += number
    }
    return sumOfNumber
}
let sum = increatmultableAdd(numbers: 1,2,3,4,5,6,9,10)

• 傳參與引用

func incrementStepTwo ( myNumber:inout Int) {
    myNumber += 2
}
var myTestNumber = 6
incrementStepTwo(myNumber: &myTestNumber)

inout關(guān)鍵字修飾形參 可以修改形參的值

• 默認形參值

/*
    默認形參值
*/
func sayLove(name:String = "涼", loveName:String = "涼") -> String {
    return "\(name)love\(loveName)"
}
sayLove()
sayLove(name: "祝英臺", loveName: "梁山伯")
sayLove(name: "他")
sayLove(loveName:"他")

• 函數(shù)類型

//定義兩個函數(shù)類型相同的函數(shù)
func diff (number1:Int, number2:Int) -> Int {
    return number1 - number2
}

func mul (number1:Int, number2:Int) -> Int {
    return number1 * number2
}

//定義兩種計算的枚舉類型
enum countType:Int {
    case diffCount = 0
    case mulCount
}

//選擇類型的函數(shù)并返回相應(yīng)的函數(shù)類型
func choiseCountType(countype:countType) -> ((Int, Int) -> Int) {
    //函數(shù)類型變量
    var myFuncType:(Int, Int) -> Int
    
    switch countype {
    case .diffCount:
        myFuncType = diff(number1:number2:)
    case .mulCount:
        myFuncType = mul(number1:number2:)
    }
    return myFuncType
}

//定義相應(yīng)的函數(shù)類型的變量來接收函數(shù)中返回的函數(shù)類型在調(diào)用
var myFuncType:(Int, Int) -> Int
myFuncType = choiseCountType(countype: .diffCount)
myFuncType(20, 10)

myFuncType = choiseCountType(countype: .mulCount)
myFuncType(10, 10)

• 函數(shù)嵌套

func choiseCountType(countType:countType) -> ((Int, Int) ->Int) {
    //定義兩個函數(shù)類型相同的函數(shù)
    func diff (number1:Int, number2:Int) -> Int {
        return number1 - number2
    }
    
    func mul (number1:Int, number2:Int) -> Int {
        return number1 * number2
    }
    
    var myFuncType:(Int, Int) -> Int
    switch countType {
    case .diffCount:
        myFuncType = diff(number1:number2:)
    case .mulCount:
        myFuncType = mul(number1:number2:)
    default:
        break
    }
    return myFuncType
}
var myFuncType:(Int, Int) -> Int
myFuncType = choiseCountType(countType: .diffCount)
myFuncType(30, 10)
myFuncType = choiseCountType(countType: .mulCount)
myFuncType(30, 10)

閉包

定義一個閉包變量其實就是定義一個特定函數(shù)類型的變量（！強制打開閉包）

• closure 變量的申明

//沒有賦初始值的變量，用？表示為可選類型的變量，在使用時用！強制打開
var myClosure0: ((Int, Int) -> int)?

//typealias關(guān)鍵字定義一個特定函數(shù)類型
typealias MyClosureType = (Int, Int) -> Int
var myClosure1: MyClosureType?

• closure變量的賦值

//參數(shù)列表跟真正的函數(shù)體之間用關(guān)鍵字 in 分隔
myClosure0 = {(num1:Int, num2:Int) -> Int in
    return num1 + num2
}
myClosure0!(10, 50)

• 閉包回調(diào)應(yīng)用實例

/*
firstVC
*/
//實現(xiàn)回調(diào)，接收回調(diào)過來的值
    secVC.setbackMyClosure {[weak self](inputText:String) in
      self?.showtextLabel.text = inputText
    }

/*
secondVC
*/
 //定義閉包類型
    typealias InputClosureType = (String) -> Void
    var backClosure:InputClosureType?//接收上個頁面?zhèn)鬟^來的閉包塊
//閉包變量的setter方法
    func setbackMyClosure(tmpClosure:@escaping InputClosureType) {
        backClosure = tmpClosure
    }
    @IBAction func BtnClick(_ sender: UIButton) {
            if backClosure != nil {
                let tmpStr = textFiel.text
                if tmpStr != nil {
                    backClosure!(tmpStr!)//
                }
                navigationController?.popViewController(animated: true)
            }
        }

• 數(shù)組中常用的閉包函數(shù)

  • Map(映射)

    //對數(shù)組中的每一項進行遍歷，通過映射對每一項進行處理，處理后的結(jié)果以新的數(shù)組出現(xiàn)，原來的數(shù)組元素保持不變
    var family = [1,2,3,4,5,6]
    var familyMap = family.map {(item: Int) -> String in
        return "我是小\(item)"
    }
    

  • Filter(過濾器)

    //Filter返回新的符合條件的數(shù)組
    var heightPerson = [170, 188,190,175,168]
    let heightOfFilter = heightPerson.filter{ (height:Int) -> Bool in
        return height >= 173
    }
    heightPerson// [170, 188,190,175,168]
    heightOfFilter//[188, 190, 175]
    

  • Reduce

    //Reduce 合并數(shù)組的items返回合并后的value
    

let salary = [1000, 2000, 3000, 4000, 5000]
let sumSalary = salary.reduce(0) { (sumSalaryTemp:Int, salaryItems:Int) -> Int in
return sumSalaryTemp + salaryItems
}
sumSalary
```