Swift3.0 - 真的很简单
Swift3.0 - 数据类型
Swift3.0 - Array
Swift3.0 - 字典
Swift3.0 - 可选值
Swift3.0 - 集合
Swift3.0 - 流控制
Swift3.0 - 对象和类
Swift3.0 - 属性
Swift3.0 - 函数和闭包
Swift3.0 - 初始化和释放
Swift3.0 - 协议protocol
Swift3.0 - 类和结构体的区别
Swift3.0 - 枚举
Swift3.0 - 扩展
Swift3.0 - 下标
Swift3.0 - 泛型
Swift3.0 - 异常错误
Swift3.0 - 断言
Swift3.0 - 自动引用计数(strong,weak,unowned)
Swift3.0 - 检测API
Swift3.0 - 对象的标识
Swift3.0 - 注释
Swift3.0 - 元类型
Swift3.0 - 空间命名
Swift3.0 - 对象判等
Swift3.0 - 探究Self的用途
Swift3.0 - 类簇
Swift3.0 - 动态调用对象(实例)方法
Swift3.0 - 文本输出
Swift3.0 - 黑魔法swizzle
Swift3.0 - 镜像
Swift3.0 - 遇到的坑
让学习成为一种习惯
Swift源码下载地址
中文翻译文档 https://github.com/numbbbbb/the-swift-programming-language-in-chinese
基本数据类型
- 使用let定义常量
let myConstant = 42
*使用var 定义变量
var myVariable = 42
myVariable = 50
- 有初始化你可以指定变量类型或者让系统自己去推断
let implicitInteger = 70
let implicitDouble = 70.0
let explicitDouble: Double = 70
- 没有初始化,你要必须指定变量类型
var numb:Double
- 在swift 中字符串是基本类型
let label = "The width is "
let width = 94
- 如何实现数据之间的相互转换
let width = 94
let widthLabel:String = String(width)
- 使用最简单的方式将其他数据类型编程字符串
let apples = 3
let oranges = 5
let fruitSummary = "I have \\(apples + oranges) pieces of fruit."
- 数组也是基本类型,不再是OC中引用类型
var shoppingList = ["catfish", "water", "tulips", "blue paint"]
shoppingList[1] = "bottle of water"
- 如何定义一个空数组
let emptyArray = [String]()
let emptyArray:[String] = []
- 字典也是基本类型
var occupations = [
"Malcolm": "Captain",
"Kaylee": "Mechanic",
]
- 将数组清空
var shopingList1 = ["1","2"]
shopingList1 = [] // 如果你这个类型,是系统可以推断的类型,你可以这样清空数组或者初始化
- 定义一个空字典
let emptyDictionary = [String: Float]()
let emptyDictionary:[String: Float] = [:]
- 清空字典
var dictionary = [1:"2"]
dictionary = [:]
可选值
let nickName: String? = nil
"?" 这个简单意思,你的变量可能为nil，或者你可能将nil赋值给它,需要给变量定义的时候加上"?",否则一旦你将nil赋值给没有加"?"的变量,编译就会报错
举个例子理解一下,我们假如有一个盒子,盒子是一个存在的物体,swift不允许有空值出现,那我们怎么办呢？就需要把空值装到一个盒子里面,系统检查的时候,发现有一个盒子,哦,好的,检测通过,但是如果你把盒子打开系统就会报错
运行下面的代码:
let nickName: String? = "酷走天涯"
print(nickName)
结果:
Optional("酷走天涯")
发现有个Optional 就说明这个变量被包着,那么怎么才能不让它包裹着呢? 很简单, 给变量加一个"!"
print(nickName!)
运行:
酷走天涯
我们还有一种解包的方式
let nickName: String? = nil
let fullName: String = "XUJIE"
let informalGreeting = "Hi \\(nickName ?? fullName)"
print(informalGreeting)
运行
Hi XUJIE
如果第一个解包值发现为nil,则使用第二值
控制流
- for ... in 循环
// 遍历数组
let individualScores = [75, 43, 103, 87, 12]
var teamScore = 0
for score in individualScores {
if score > 50 {
teamScore += 3
} else {
teamScore += 1
}
}
print(teamScore)
// 遍历 字典
let interestingNumbers = [
"Prime": [2, 3, 5, 7, 11, 13],
"Fibonacci": [1, 1, 2, 3, 5, 8],
"Square": [1, 4, 9, 16, 25],
]
var largest = 0
for (kind, numbers) in interestingNumbers {
for number in numbers {
if number > largest {
largest = number
}
}
}
// 还可以这样使用循环
var total = 0
for i in 0..<4 {
total += i
}
print(total)
- Switch
let vegetable = "red pepper"
switch vegetable {
case "celery":
print("Add some raisins and make ants on a log.")
case "cucumber", "watercress":
print("That would make a good tea sandwich.")
case let z where z.hasSuffix("pepper"):
print("Is it a spicy \\(z)?")
default:
print("Everything tastes good in soup.")
}
注意 z 什么 随便写个变量名就可以了
- while 循环
var n = 2
while n < 100 {
n = n * 2
}
print(n)
- repeat ...while
var m = 2
repeat {
m = m * 2
} while m < 100
print(m)
函数和闭包
*定义函数
func greet(person: String, day: String) -> String {
return "Hello \\(person), today is \\(day)."
}
greet(person: "Bob", day: "Tuesday")
- 缺省参数名
func greet(_ person: String, _ day: String) -> String {
return "Hello \\(person), today is \\(day)."
}
greet("John", "Wednesday")
- 返回值可以是元祖类型
func calculateStatistics(scores: [Int]) -> (min: Int, max: Int, sum: Int) {
var min = scores[0]
var max = scores[0]
var sum = 0
for score in scores {
if score > max {
max = score
} else if score < min {
min = score
}
sum += score
}
return (min, max, sum)
}
let statistics = calculateStatistics(scores: [5, 3, 100, 3, 9])
print(statistics.sum)
print(statistics.2)
- 定义多个类型相同的参数
func sumOf(numbers: Int...) -> Int {
var sum = 0
for number in numbers {
sum += number
}
return sum
}
sumOf()
sumOf(numbers: 42, 597, 12)
- 函数嵌套使用
func returnFifteen() -> Int {
var y = 10
func add() {
y += 5
}
// 方法内部定义方法,声明周期为方法
add()
return y
}
returnFifteen()
- 函数当返回值
func makeIncrementer() -> ((Int) -> Int) {
func addOne(number: Int) -> Int {
return 1 + number
}
return addOne
}
var increment = makeIncrementer()
increment(7)
- 函数当参数
func hasAnyMatches(list: [Int], condition: (Int) -> Bool) -> Bool {
for item in list {
if condition(item) {
return true
}
}
return false
}
func lessThanTen(number: Int) -> Bool {
return number < 10
}
var numbers = [20, 19, 7, 12]
hasAnyMatches(list: numbers, condition: lessThanTen)
对象和类
- 定义一个类
class Shape {
var numberOfSides = 0
func simpleDescription() -> String {
return "A shape with \\(numberOfSides) sides."
}
}
- 初始化方法,和对象方法
class NamedShape {
var numberOfSides: Int = 0
var name: String
// 初始化方法
init(name: String) {
self.name = name
}
// 成员方法定义
func simpleDescription() -> String {
return "A shape with \\(numberOfSides) sides."
}
}
- 继承
class Square: NamedShape {
var sideLength: Double // 如果不是可选类型 必须在初始化方法中初始化
init(sideLength: Double, name: String) {
self.sideLength = sideLength
super.init(name: name) // 调用父类的初始化方法
numberOfSides = 4 // 给父类的属性赋值之前必须先调用父类的初始化方法
}
func area() -> Double {
return sideLength * sideLength
}
// 重写父类的方法
override func simpleDescription() -> String {
return "A square with sides of length \\(sideLength)."
}
}
- setter 和 getter
class EquilateralTriangle: NamedShape {
var sideLength: Double = 0.0 // 定一个属性
init(sideLength: Double, name: String) {
self.sideLength = sideLength
super.init(name: name)
numberOfSides = 3
}
// 这个是setter 和geterr方法的定义
var perimeter: Double {
get {
return 3.0 * sideLength
}
set {
sideLength = newValue / 3.0
}
}
override func simpleDescription() -> String {
return "An equilateral triangle with sides of length \\(sideLength)."
}
}
- 观察属性
class TriangleAndSquare {
// 定一个三角形对象
var triangle: EquilateralTriangle {
willSet {
square.sideLength = newValue.sideLength
}
}
// 定一个一个正方形对象
var square: Square {
willSet {
triangle.sideLength = newValue.sideLength
}
}
// 通过检测属性,我们让两个对象的边保持一样长
init(size: Double, name: String) {
square = Square(sideLength: size, name: name)
triangle = EquilateralTriangle(sideLength: size, name: name)
}
}
var triangleAndSquare = TriangleAndSquare(size: 10, name: "another test shape")
print(triangleAndSquare.square.sideLength)
print(triangleAndSquare.triangle.sideLength)
triangleAndSquare.square = Square(sideLength: 50, name: "larger square")
print(triangleAndSquare.triangle.sideLength)
运行结果
10.0
10.0
50.0
枚举类型
- 定义
enum Rank: Int { // Int 设置枚举值的类型
// 定义枚举值设置值
case ace = 1
// 可以case 后面一次定义多个枚举值
case two, three, four, five, six, seven, eight, nine, ten
case jack, queen, king
// 定义函数 如果多人合作的时候,可以使用这个让别人更加了解你定义的属性的含义
func simpleDescription() -> String {
switch self { // self 就是这个枚举本身
case .ace:
return "ace"
case .jack:
return "jack"
case .queen:
return "queen"
case .king:
return "king"
default:
return String(self.rawValue)
}
}
}
// 使用
let ace = Rank.ace
let aceRawValue = ace.rawValue
问题1 如何想OC 一样使用 | 或操作呢?
结构体
- 定义
struct Card {
// 定义结构体
var rank: Rank
var suit: Suit
// 结构体内可以定义方法
func simpleDescription() -> String {
return "The \\(rank.simpleDescription()) of \\(suit.simpleDescription())"
}
}
- 使用
let threeOfSpades = Card(rank: .three, suit: .spades)
let threeOfSpadesDescription = threeOfSpades.simpleDescription()
协议
- 定义
protocol ExampleProtocol {
var simpleDescription: String { get }
mutating func adjust()
}
- 给类添加协议
class SimpleClass: ExampleProtocol {
var simpleDescription: String = "A very simple class."
var anotherProperty: Int = 69105
func adjust() {
simpleDescription += " Now 100% adjusted."
}
}
- 给结构体添加协议
struct SimpleStructure: ExampleProtocol {
var simpleDescription: String = "A simple structure"
mutating func adjust() {
simpleDescription += " (adjusted)"
}
}
- 定义一个协议变量
let protocolValue: ExampleProtocol = a
print(protocolValue.simpleDescription)
扩展
例子:给Int 添加一个协议
extension Int: ExampleProtocol {
var simpleDescription: String {
return "The number \\(self)"
}
mutating func adjust() {
self += 42
}
}
print(7.simpleDescription)
错误操作
- 定义一个错误枚举
enum PrinterError: Error {
case outOfPaper
case noToner
case onFire
}
- 定义一个有异常处理能力的函数
func send(job: Int, toPrinter printerName: String) throws -> String {
if printerName == "Never Has Toner" {
throw PrinterError.noToner
}
return "Job sent"
}
- 捕捉异常
do {
let printerResponse = try send(job: 1040, toPrinter: "Bi Sheng")
print(printerResponse)
} catch {
print(error)
}
- 异常分类处理
do {
let printerResponse = try send(job: 1440, toPrinter: "Gutenberg")
print(printerResponse)
} catch PrinterError.onFire {
print("I'll just put this over here, with the rest of the fire.")
} catch let printerError as PrinterError {
print("Printer error: \\(printerError).")
} catch {
print(error)
}
总结
Swift 的基本语法已经了解完毕,但这只是些简单的东西,如果Swift只是这些东西,那我们就没有学习的必要了,Swift的灵活性,优秀的设计模式,从上面的内容体现不出来,我会在后面几篇文章中,阐述它的高级用法!
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