Swift學習-Enumerate、Structure
阿新 • • 發佈：2021-06-29
1.列舉
1.1列舉定義
//列舉型別可以省略
enum enumName : type?{
case value1
case value2
}
定義一個星期列舉
enum DaysOfAWeek{ case Monday case Tuesday case Wednesday } 也可以寫為 enum DaysOfAWeek{ case Monday, Tuesday,Wednesday } //列舉值按以下方式指定給變數 var today = DaysOfAWeek.Monday today = .Tuesday //與Switch聯合使用 switch today { case .Monday: print("Today is Monday") case .Tuesday: print("Today is Tuesday") case .Wednesday: print("Today is Wednesday") default: print("Today is neither Monday nor Tuesday") }
定義列舉初始值
enum DaysOfAWeek{
case Sunday
case Monday
case Tuesday
case Wednesday
init() {
self = .Sunday
}
}
var today = DaysOfAWeek()
//此時預設為：Sunday
關聯值，列舉允許每個case有一個或更多型別引數
enum ValuesOfDifferentType{ case Str(String) case Inte(Int) case Numb(Double) case LatLng(Double,Double) case Boo(Bool) init(){ self = .Str("Hello World") } }
此時可以結合switch，根據case中的入參，返回不同的值
enum ValuesOfDifferentType{
case Str(String)
case Inte(Int)
case Numb(Double)
case LatLng(Double,Double)
case Boo(Bool)
init(){
self = .Str("Hello World")
}
}
在moya網路請求封裝中就使用到了；使用moya封裝網路請求時，需要定義一個列舉，遵循TargetType；列舉中定義需要訪問的介面型別，大多根據介面功能定義case；因為我們專案請求介面定義比較標準，大都使用一個入參格式，所以我沒有將全部的介面展示，只區分了上傳、下載以及post請求。程式碼片段如下
public enum SWNetworkAPI{
case requestWithVersion(params: [String: Any])//請求
case requestUploadImage(params: [String: Any],urlParams:[String : Any])//上傳圖片
case requestUploadImages(params: [UIImage],urlParams:[String : Any])//批量上傳圖片
}
//通過擴充套件遵循協議 : 當一個型別已經符合了某個協議中的所有要求，卻還沒有宣告遵循該協議時，可以通過空擴充套件體的擴充套件來遵循該協議：
//從現在起，SWNetworkAPI的例項可以作為 TargetType 型別使用：
extension SWNetworkAPI : TargetType {
//伺服器地址
public var baseURL: URL {
switch self {
case .requestWithVersion:
return URL.init(string: TSP_BASE_URL)!
case .requestUploadImage:
return URL.init(string: TSP_BASE_URL)!
case .requestUploadImages:
return URL.init(string: TSP_BASE_URL)!
}
}
//各個請求的具體路徑
public var path: String {
switch self {
case .requestWithVersion:
return TSP_POST_PATH
case .requestUploadImage:
return TSP_UPLOAD_IMAGE
case .requestUploadImages:
return TSP_UPLOAD_IMAGES
}
}
//請求型別
public var method: Moya.Method {
switch self {
case .requestWithVersion:
return .post
case .requestUploadImage:
return .post
case .requestUploadImages:
return .post
}
}
//請求任務事件（帶上引數）
public var task: Task {
switch self {
case .requestWithVersion(let params):
//根據入參，生成task，返回task
return .requestParameters(parameters: params, encoding: JSONEncoding.default)
case .requestUploadImage(let params,let urlParams):
case .requestUploadImages(let params,let urlParams):
return .uploadCompositeMultipart(formDataArray as! [Moya.MultipartFormData], urlParameters: urlParams)
}
}
//定義請求頭
public var headers: [String : String]? {
switch self {
case .requestWithVersion:
return ["Content-type" : "application/json;charset=utf-8;","Accept-Language":"zh-CN"]
case .requestUploadImage:
return ["Content-Type" : "Multipart/form-data","Accept": "application/json;charset=utf-8"]
case .requestUploadImages:
return ["Content-Type" : "Multipart/form-data","Accept": "application/json;charset=utf-8"]
}
}
}
言歸正傳！！！
定義列舉型別,列舉可以向變數和常量一樣定義一個型別；下面定義的就是一個String型別的列舉。
*注意：
1.列舉型別的原始值，必須是字面量
2.只有定義了列舉型別，才可以給case賦值
3.如果沒有定義列舉型別
enum DaysOfAWeek : String{
case Sunday = "Today is Sunday"
case Monday = "Today is Monday"
case Tuesday = "Today is Tuesday"
case Wednesday
}
然後可以根據rawValue獲取，列舉的具體值
var today = DaysOfAWeek.Sunday.rawValue//列印結果：Today is Sunday
today = DaysOfAWeek.Wednesday.rawValue//列印結果：Wednesday
也可以通過rawValue檢索列舉中的case值。
var possibleDay = DaysOfAWeek(rawValue: "Today is Monday")
print(possibleDay ?? "Day doesn't exist")
//列印結果：Monday
possibleDay = DaysOfAWeek(rawValue: "Thursday")
print(possibleDay ?? "Day doesn't exist")
//列印結果：Day doesn't exis
自動設定原始值
列舉可以自動設定case原始值,當列舉型別為Int、Double、float
//例子1
enum Numbers : Int{
case caseOne = 100, caseTwo
case caseThree
}
var num = Numbers.caseOne.rawValue//列印結果：100
num = Numbers.caseTwo.rawValue//列印結果：101
num = Numbers.caseThree.rawValue//列印結果：102
//例子2
enum NumbersO : Int{
case caseOne
case caseTwo = 2
case caseThree
}
var numO = NumbersO.caseOne.rawValue//列印結果：0
numO = NumbersO.caseTwo.rawValue//列印結果：2
numO = NumbersO.caseThree.rawValue//列印結果：3
//例子3
enum NumbersT : Int{
case caseOne = 100, caseTwo = 2
case caseThree
}
var numT = NumbersT.caseOne.rawValue//列印結果：100
numT = NumbersT.caseTwo.rawValue//列印結果：2
numT = NumbersT.caseThree.rawValue//列印結果：3
將列舉轉換成字串
enum DaysOfAWeek : String{
case Sunday
case Monday
case Tuesday
case Wednesday
func day()->String{
return self.rawValue
}
}
var str = DaysOfAWeek.Sunday.day()
print(str)//列印結果:Sunday
2.Struct
struct 定義
struct Name{
//properities here
}
定義一個矩形
struct Rectangle{
var width = 0
var height = 0
}
要訪問或修改結構體的屬性我們用點操作符
var rectangle = Rectangle()
print(rectangle.width)//列印結果：0
print(rectangle.height)//列印結果：0
rectangle.width = 10
rectangle.height = 10
如果初始化的結構，是常量，結構體中的屬性值不能修改
let rectangleConstant = Rectangle()
rectangleConstant.height = 20//報錯
rectangleConstant.width = 20//報錯
struct Circle{
let radius = 0
}
var circle = Circle()
circle.radius = 10//報錯
結構體中定義函式
struct Rectangle {
var width = 0
var height = 0
//手動輸入寬高，獲取面積
func area(width :Int, height: Int) -> String
{
return "Area is \(width*height)"
}
//根據結構體內部引數值，獲取面積
func area() -> String{
return "Return area is \(self.width * self.height)"
}
//修改引數
mutating func printModifiedWidth() -> String
{
width = width*2
return "Modified width is \(width)"
}
//自定義初始化方法
init(width: Int, height: Int) {
self.width = width*2
self.height = height*2
}
//初始化委託
init(width: Int){
self.init(width: width,height: width)
}
//預設宣告，不然空初始化會報錯
init(){
self.init(width: 0,height: 0)
}
//靜態函式
static func printString() -> String
{
return "Hello how you're doing"
}
}
//使用如下所示的結構例項呼叫函式
var rectangle = Rectangle()
rectangle.width = 10
rectangle.height = 10
rectangle.area(width:rectangle.width,height:rectangle.height)
rectangle.area()
//如果要在函式中修改屬性值，我們需要用關鍵字mutating來標記函式，然後給屬性重新賦值
//結構體中的屬性不能在內部函式中修改，將函式宣告為內部突變函式，將允許我們改變結構體中的屬性
rectangle.printModifiedWidth()
print(rectangle.width)//列印結果：20
//結構體初始化有兩種形式，
//1.空的初始化（）
var rectangleInitial = Rectangle()
//2.也可以是在括號內列出結構屬性的成員初始值設定項，以便可以為它們指定新值，但是麻煩再需要給每個屬性都賦值
var rectangleInitialMemberWise = Rectangle(width:10,height:10)
//我們也可以在結構體內部自定義初始化方法
var rectangleCustom = Rectangle(width: 10, height: 10)
print(rectangleCustom.width) //prints 20
print(rectangleCustom.height) //prints 20
var square = Rectangle.init(width:20)
print(square.width) //prints 40
print(square.height) //prints 40
//結構體內部的靜態函式可以在不建立結構例項的情況下呼叫
Rectangle.printString()//列印結果：Hello how you're doing
可以使用以下語法動態計算屬性
get:當屬性值改變時，自動改變area
struct Rectangle {
var width = 0
var height = 0
var area: Int {
get {//計算結果
return width*height
}
set {//初始值
area = 0
}
}
}
var rectangle = Rectangle()
print(rectangle.area) //prints 0
rectangle.width = 20
rectangle.height = 20
print(rectangle.area) //prints 400
Swift結構是通過值傳遞的，而不是通過引用傳遞的
var rect = rectangle
rect.width = 30
print(rectangle.width) //prints 20 and NOT 30