Swift3 從入門到精通Day6：閉包Closure
時間：5/12（五）
內容：
- 41. 閉包：沒有名字的函式7:05
- 42. 閉包：有型別可當函式參數的閉包6:09
- 43. 閉包：可以當作函式回傳值的閉包6:46
- 44. 閉包：省略簡寫方法5:20
- 45. 閉包：閉包與陣列的 Map 方法10:50
- 46. 閉包：閉包與陣列的 Filter方法3:34
41. 閉包：沒有名字的函式
Closure閉包：沒有名字的函式
函式轉Closure的步驟
- 刪除關鍵字func 刪除函式名稱
- 把參數跟回傳值一到大括號中
- 加入in
let helloClosure = {“Hello Everbody”}
helloClosure()
func eat(foodName:String){
“I want to eat \(foodName)”
}
eat(foodName: “Pizza”)
//How to chage to Closure
let eatClosure = {
(foodName:String) in
“I want to eat \(foodName)”}
eatClosure(“apple pie”)
func add(number1:Int,number2:Int) -> Int{
let result = number1 + number2
return result
}
add(number1: 3, number2: 13)
//How to chage to Closure
let addClosure = {
(number1:Int,number2:Int) -> Int in
let result = number1 + number2
return result
}
add(number1: 3, number2: 13)
func multuply(number1:Int,number2:Int) -> String {
return “\(number1) * \(number2) = \(number1 * number2)”
}
multuply(number1: 4, number2: 3)
//How to chage to Closure
let multuplyClosure = {(number1:Int,number2:Int) -> String in
return “\(number1) * \(number2) = \(number1 * number2)”
}
multuply(number1: 4, number2: 3)
- 42. 閉包：有型別可當函式參數的閉包6:09
func calculate(num1:Int,num2:Int,operation:(Int,Int) -> (Int)){
print(operation(num1,num2))
}
calculate(num1: 3, num2: 8, operation: addClosure)
- 43. 閉包：可以當作函式回傳值的閉包6:46
- 44. 閉包：省略簡寫方法5:20
- 已經能夠確認的參數與回傳值的型別的話，可以刪除Closure裡面的參數跟回傳值。
- 程式碼只有一行的情況下，可以刪除return
- 用$0 $1等，代替傳進來的參數名稱。
- 如果是最後或唯一的參數，可以把Closure移至參數小括號外。
- 如果是唯一參數，可省略參數小括號。
let addClosure:(Int,Int)->(Int) = {
(number1:Int,number2:Int) -> Int in
return = number1 + number2
}
////簡化
let addClosure:(Int,Int)->(Int) = { $0 + $1 }
- 45. 閉包：閉包與陣列的 Map 方法10:50
var numberArray = [1,2,5,7,9,2,4,6,8,10]
numberArray.count
//加入numberArray.append(27)
let numberArrayAddTen = numberArray.map({
(number:Int) ->Int in
return number+20
})
numberArrayAddTen
let numberArrayToString =
numberArray.map({
(a:Int) -> String in
return”This is number \(a)”
})
numberArrayToString
//簡略
- 已經能夠確認的參數與回傳值的型別的話，可以刪除Closure裡面的參數跟回傳值。
- 程式碼只有一行的情況下，可以刪除return
- 用$0 $1等，代替傳進來的參數名稱。
- 如果是最後或唯一的參數，可以把Closure移至參數小括號外。
- 如果是唯一參數，可省略參數小括號。
let numberArrayAddTen = numberArray.map{$0+20}
let numberArrayToString =numberArray.map{
“This is number \($0)”
}
- 46. 閉包：閉包與陣列的 Filter方法3:34
var numberArray = [1,2,5,7,9,2,4,6,8,10]
numberArray.filter({
(number:Int) ->Bool in
return number % 2 == 0
})
numberArray.filter({
(number:Int) ->Bool in
return number > 5
})
//簡化
let evenNumber = numberArray.filter{ $0 %2 ==0 }
let evenNumber = numberArray.filter{ $0 > 5 }
