基本使用
//导入框架
import Foundation
//定义变量及常量
let a : Int =10
var i = 10
//打印输出
print(a)
区间：
//表示0~9的两种写法
0..<10
0...9
switch
//支持 浮点、字符串、区间
let score = 80
switch score {
case 0..<60: print(不合格)
case 60..<80: print(合格)
case 80...100: print(优秀)
}
循环
for i in 0...10 {
print(i)
}
for _ in 0...10 {
print("hello swift")
}
var m = 0
while m<10 {
m += 1
}
repeat {
m -= 1
} while m>0
字符串
let name = "herui"
let age = 18
let info = name + age
let infoDesc = "name is \(name), age is \(age)"
let strLen = infoDesc.characters.count
let min = 3
let sec = 12
let time = String(format:"%02d:%02d", min, sec)
数组
var arr = ["abc", "def"]
arr.append("ghi")
arr.remove(at: 0)
arr[0] = "xxx"
//数组遍历
let count = arr.count
for i in (0..<count) {
}
for item in arr {
}
for (index, item) in arr.enumerated() {
}
//数组合并
let arr1 = ["a", "b"]
let arr2 = ["c", "d"]
let arr3 = arr1 + arr2
字典
var dict : [String : Any] = ["name" : "herui", "age" : 18]
`var dict = [String : Any]()`
dict["gender"] = "男" //可增加可修改
dict.removeValue(forKey:"name")
//字典遍历
for key in dict.keys {
}
for value in dict.values {
}
for (key, value) in dict {
}
字典不可以直接相加合并，即使类型一致
元组
//数组
var infoArray : [Any] = ["herui", 18]
//取出来的值类型是Any，需要as转换成明确的类型再进行操作
infoArray[0] as! String
infoArray[1] as! Int
//字典
var infoDict : ["String":Any] = ["name":"herui", "age":18]
infoDict["name"] as! String
infoDict["age"] as! Int
//元组
var infoTuple = (name:"herui", age:18)
//无需转换（使用方便，无需类型转换）
infoTuple.name
infoTuple.age
Optional可选类型
//声明为可选类型，即表示它的值可能为nil
var name : Optional<String> = nil
var name : String? = nil
name = "herui" //xcode自动包装为name = Optional("herui")
//强制解包，如果值为nil时会崩溃
name!
//先判断，再解包
if(name != nil){
name!
}
//可选绑定（先判断是否为nil，再解包）推荐使用
if let name = name {
name //直接用
}
as类型转换
var dict : ["String":Any] = ["name":"herui", "age":18]
//用 as? 将Any转换为可选类型
let name = dict["name"] as? String
//用 as! 将Any转换为具体类型，如果为nil时程序崩溃
let name = dict["name"] as! String
//常见用法（从字典中取值）
if let name = dict["name"] as? String {
//name为具体类型
}
func函数
func say() {
}
func say() -> String {
}
func say(str: String) -> String {
}
枚举类型
enum MethodType : String {
case GET = "GET"
case POST = "POST"
}
MethodType.GET
enum Direction {
case east, west, north, south
}
Direction.east
struct结构体
//结构体中可以有方法及属性
struct Location {
var x : Float
var y : Float
//构造方法名固定为init
//方法内部需要初始化所有的属性
init(x: Float, y: Float) {//如果不写，这个方法会默认生成
self.x = x
self.y = y
}
init(str : String) {
let arr = str.components(separatedBy: ",");
self.x = Float(arr[0]) ?? 0
self.y = Float(arr[1]) ?? 0
}
func desc() -> String {
return "x is \(self.x), y is \(self.y)"
}
}
var loc = Location(x: 0, y: 0)
loc.x = 1.2
let desc = loc.desc()
print(desc)
var loc2 = Location(str: "12,22")
print(loc2)
class类
class Student {
//存储属性
var english : Double = 0.0
var math : Double = 0.0
//计算属性（只读）
var ave : Double {
return (english + math ) * 0.5;
}
//类属性
static var desc : String = "Student"
//属性监听
var name : String = "" {
willSet{
print("willSet新值" + newValue)
print("willSet未改变前的值" + name)
}
didSet{
print("didSet改变前的旧值" + oldValue)
print("didSet新值" + name)
}
}
//默认构造函数
init() { }
//自定义构造函数
init(dict: [String : Any]) {
if let name = dict["name"] as? String {
self.name = name
}
if let math = dict["math"] as? Double {
self.math = math
}
}
//析构函数
deinit {
print("deinit")
}
}
let stu = Student()
stu.english = 90
stu.math = 60
print(stu.ave)
let stu2 = Student(dict: ["name": "herui", "math" : 66.0])
print(stu2.name)
print(stu2.math)
var stu3 : Student? = Student()
stu3 = nil
protocol协议
@objc protocol PersonDelegate : class {
//必须实现
func run()
//可选实现需要加上optional，但是optional是OC部分的东西，所以加上@objc
@objc optional func fly()
}
class Person : NSObject, PersonDelegate {
//只有声明协议只能被class遵守时，delegate这里才能加上weak（防止循环引用）
weak var delegate : PersonDelegate?
func run() {
print("run")
}
}
闭包(block)
(参数列表)->(返回值)
/**
为了模拟循环引用的问题，在vc里强引用了req，在req里强引用了completion闭包，而completion里又强引用了vc，导致循环引用。
解决办法：在block回调里面用[weak self]打破了循环引用
*/
class RequestManager {
var url : String = ""
var completion : ((_ result : String)->())?
func request(completion : @escaping (_ result : String)->()){
self.completion = completion
DispatchQueue.global().async {
print("请求数据中。。")
DispatchQueue.main.async {
print("请求到数据")
completion("url: \(self.url)")
}
}
}
}
class ViewController {
var name = "ViewController"
var req : RequestManager?
func test() {
req = RequestManager();
req?.url = "http://www.baidu.com";
req?.request { [weak self] (str) in
print("name: \(self?.name ?? ""), result: \(str)")
}
}
deinit {
print("ViewController - deinit")
}
}
var vc : ViewController? = ViewController()
vc?.test()
vc = nil
懒加载
class ViewController {
lazy var info = ["herui", 18]
lazy var button : UIButton = {
let btn = UIButton()
return btn
}()
}
访问权限
class Person {
//默认，全包访问
internal var name = "herui"
//私有，仅本类
private var age = 18
//公开，跨包访问 UIView.frame
open var height = 1.88
//当前文件可访问
fileprivate var weigth = 120
}
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