swift语言的学习笔记

swift参考了OC，Rust,Haskell,Ruby,Python,C#等语言的特性。首先，学习这门语言是速学的，我不想浪费太多时间在笔记这门语言和其他语言的哪里不同，特性你自己亲自实践就知道了。下面是我亲自实践总结的一点点皮毛而已。

废话不多说，直接上代码：

1 声明变量和常量

var str: String = "Look what I can do"
var age: Int = 18

let favoriteNumber: Int = 42

代替上面的简单写法就是：

var str = "Look what I can do"
var age = 18

let favoriteNumber = 42

2 字符串声明和初始化或者说是直接赋值

var favoriteGame: String = "Mario Kart"
favoriteGame = "Super Smash Bros"

3 操作符的使用与if语法

let batmanCoolness = 10
var supermanCoolness = 9
let aduamanCoolness = 1
batmanCoolness < supermanCoolness
batmanCoolness > supermanCoolness
supermanCoolness >= 8
batmanCoolness == (supermanCoolness + aduamanCoolness)
batmanCoolness > aduamanCoolness && batmanCoolness == (aduamanCoolness + supermanCoolness)
batmanCoolness < supermanCoolness || aduamanCoolness < supermanCoolness

var spidermanCoolness = 7
(spidermanCoolness + aduamanCoolness) > supermanCoolness
spidermanCoolness == 7 && aduamanCoolness == 2

if(batmanCoolness > spidermanCoolness){

spidermanCoolness = spidermanCoolness - 1

}else if(batmanCoolness >= spidermanCoolness){

spidermanCoolness = spidermanCoolness - 1

}else{

spidermanCoolness = spidermanCoolness + 1
}

if(supermanCoolness < spidermanCoolness)  {
    supermanCoolness = supermanCoolness - 1
    spidermanCoolness = spidermanCoolness + 1
} else if (supermanCoolness == spidermanCoolness)  {
    supermanCoolness = supermanCoolness + 1
    spidermanCoolness = spidermanCoolness + 1
} else  {
    supermanCoolness = supermanCoolness + 1
    spidermanCoolness = spidermanCoolness - 1
}

4 print 语法的使用
print("Hello,World")
print("Ry is awesome")
print(batmanCoolness)

5 字符串插入的使用

var apples = 5
print("Sally has \(apples)apples")
print("Sally has \(apples - 5) apples")

6 可选optional使用（注意：0或者一个具体值）

var optionalNumber: Int? = 5
optionalNumber = nil

if let number = optionalNumber {

print("It is a number")
}
else{

print("It is not a number")
}

7 类型转换

var languagesLearned: String = "3"
var languagesLearnedNum: Int? = Int(languagesLearned)

如：

var tutorialTeam: String = "55"
var editorialTeam = 23

var tutorialTeamNum: Int? = Int(tutorialTeam)

if let numTutorial = tutorialTeamNum  {
    if(numTutorial > editorialTeam)  {
        print("\(numTutorial) is greater than \(editorialTeam)")
    } else if (numTutorial < editorialTeam) {
        print("\(numTutorial) is less than \(editorialTeam)")
    } else  {
        print("\(numTutorial) is equal to \(editorialTeam)")
    }
} else  {
    print("Invalid entry")
}

8 方法的使用

例子：func randomIntBetween(low:Int, high:Int) -> Int {
    let range = high - (low - 1)
    return (Int(arc4random()) % range) + (low - 1)
}

新建项目PeopleDatabase

main.swift

import Foundation

//var newPerson = Person() //创建对象newPerson类的person,等于一个Person对象初始化。即可调用person类
//
//newPerson.enterInfo()
//newPerson.printInfo()

// 加入循环
var response: String
var people: [Person] = [] //创建数组

repeat{

var newPerson = Person()
    newPerson.enterInfo()
    newPerson.printInfo()
    people.append(newPerson)
    newPerson.printInfo()
    
    print("Do you want to enter another name?(y/n)")
    response = input()
}while(response == "y")

print("Number of people in the database: \(people.count)")

for onePerson in people  {
    onePerson.printInfo()
}

新建一个Person类

Person.swift

import Foundation
class Person  {//创建了一个person的类，类不仅有属性，还可以包含方法

var firstName = ""
    var lastName = ""
    var age = 0
    
    func input() -> String {
        let keyboard = NSFileHandle.fileHandleWithStandardInput()
        let inputData = keyboard.availableData
        let rawString = NSString(data: inputData, encoding:NSUTF8StringEncoding)
        if let string = rawString {
            return string.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet())
        } else {
            return "Invalid input"
        }
    }
    
    func changeFirstName(newFirstName:String) { //1创建方法
        firstName = newFirstName
    }
    
    func enterInfo()  {//2创建方法
        print("What is the first name?")
        firstName = input()
        
        print("What is \(firstName)'s last name?")
        lastName = input()
        print("How old is \(firstName) \(lastName)")
        let userInput = Int(input())
        if let number = userInput {
            age = number
        }
    }
    
    func printInfo()  {//3创建方法
//        print("First Name: \(firstName)")
        print("\(firstName) \(lastName) is \(age) years old")
    }

}

记得导入文件helpers.swift的辅助文件

helpers.swif

import Foundation

func input() -> String {
  let keyboard = NSFileHandle.fileHandleWithStandardInput()
  let inputData = keyboard.availableData
  let rawString = NSString(data: inputData, encoding:NSUTF8StringEncoding)
  if let string = rawString {
    return string.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet())
  } else {
    return "Invalid input"
  }
}

func randomIntBetween(low:Int, high:Int) -> Int {
  let range = high - (low - 1)
  return (Int(arc4random()) % range) + (low - 1)
}

9 swift的导入类的时候，不需要导入类的头文件，直接创建类直接就可以调用了，这是和OC特殊的不同点，主要是方便。节省很多开发时间和提高开发效率

10

//常量的声明
let swiftTeam = 13
let iOSTeam = 54
let otherTeams = 48
//变量 的声明和值的改变
var totalTeam = swiftTeam + iOSTeam + otherTeams
totalTeam += 1

let priceInferred = 19.99
let priceExplict: Double = 19.99
let onSaleInferred = true
let onSaleExplicit: Bool = false
let nameInferred = "Whoopie Cushion"
let nameExplicit: String = "Whoopie Cushion"
if onSaleInferred {
  print("\(nameInferred) on sale for \(priceInferred)!")
}else{
 print("\(nameInferred) at regular price: \(priceInferred)!")
}

//类的定义和调用
class TipCalculator{
    let total: Double
    let taxPct: Double
    let subtotal: Double
    
    init(total:Double,taxPct: Double){ //初始化方法
    
      self.total = total
        self.taxPct = taxPct
        subtotal = total/(taxPct + 1)
      
    }
    func cailcTipWithTipPct(tipPct: Double) -> Double {
        
        return subtotal * tipPct
    }
   
    func printPossibleTips(){
        
        print("15%:\(cailcTipWithTipPct(0.15))")
        print("18%:\(cailcTipWithTipPct(0.18))")
        print("20%:\(cailcTipWithTipPct(0.20))")
    }
    
    func returnPossibleTips() -> [Int: Double] {
        
        let possibleTipsInferred = [0.15,0.18,0.20]
        var retval = [Int: Double]()
        for possibleTip in possibleTipsInferred {
            let intPct = Int(possibleTip * 100)
            retval[intPct] = cailcTipWithTipPct(possibleTip)
        }
        return retval
    }

}
let tipCalc = TipCalculator(total: 33.25,taxPct: 0.06)
tipCalc.printPossibleTips()

11 //Unnamed Tuples元组的使用---无命名

//let tipAndTotal = (4.00,25.19）或者
let tipAndTotal:(Double,Double) = (4.00,25.19)
//元组点语法的访问index（第几个元素）
tipAndTotal.0
tipAndTotal.1
//另外设置一个元组赋值第一个元组，然后访问里面的元素
let(theTipAmt,theTotal) = tipAndTotal
theTipAmt
theTotal

//#####元组的使用 有命名
//let tipAndTotalNamed:(tipAmt:Double, total:Double) = (4.00, 25.19)也可以这样
let tipAndTotalNamed = (tipAmt:4.00,total:25.19)
tipAndTotalNamed.tipAmt
tipAndTotalNamed.total

//#####元组的使用 Returning Tuples
let total = 21.19
let taxPct = 0.06
let subtotal = total/(taxPct + 1)
func calcTipWithTipPct(tipPct:Double) -> (tipAmt:Double,total:Double) {
    
    let tipAmt = subtotal * tipPct
    let finalTotal = total + tipAmt
    return(tipAmt,finalTotal)
}
calcTipWithTipPct(0.20)

12 //A Full Prototype 完整的原型
class TipCalculatorModel {
    
    var total: Double
    var taxPct: Double
    var subtotal: Double {
        get {
            return total / (taxPct + 1)
        }
    }
    
    init(total: Double, taxPct: Double) {
        self.total = total
        self.taxPct = taxPct
    }
    
    func calcTipWithTipPct(tipPct:Double) -> (tipAmt:Double, total:Double) {
        let tipAmt = subtotal * tipPct
        let finalTotal = total + tipAmt
        return (tipAmt, finalTotal)
    }
    
    func returnPossibleTips() -> [Int: (tipAmt:Double, total:Double)] {
        
        let possibleTipsInferred = [0.15, 0.18, 0.20]
        
        var retval = [Int: (tipAmt:Double, total:Double)]()
        for possibleTip in possibleTipsInferred {
            let intPct = Int(possibleTip*100)
            retval[intPct] = calcTipWithTipPct(possibleTip)
        }
        return retval
        
    }
    
}

13 //Protocols
protocol Speaker{
  func Speak()
}
class Vicki: Speaker {
    func Speak() {
        print("Hello, I am Vicki!")
    }
}

class Ray: Speaker {
    func Speak() {
        print("Yo, I am Ray!")
    }
}
class Animal {
}
class Dog : Animal, Speaker {
    func Speak() {
        print("Woof!")
    }
}

14//Optional Protocols
@objc protocol Speak{
  func Speak()
    optional func TellJoke()
}
//If you get an error, make sure to add this line to the top of your playground:import Foundation
//protocol的使用调用
var speaker:Speaker
speaker = Ray()
speaker.Speak()
speaker = Vicki()
speaker.Speak()

15//Delegates

protocol DateSimulatorDelegate {
    func dateSimulatorDidStart(sim:DateSimulator, a:Speaker, b:Speaker)
    func dateSimulatorDidEnd(sim:DateSimulator, a: Speaker, b:Speaker)
}

class DateSimulator {
    
    let a:Speaker
    let b:Speaker
    var delegate:DateSimulatorDelegate?
    
    init(a:Speaker, b:Speaker) {
        self.a = a
        self.b = b
    }
    
    func simulate() {
        delegate?.dateSimulatorDidStart(self, a:a, b: b)
        print("Off to dinner...")
        a.Speak()
        b.Speak()
        print("Walking back home...")
//        a.TellJoke?()
//        b.TellJoke?()
        delegate?.dateSimulatorDidEnd(self, a:a, b:b)
    }
}