swift语言的学习笔记

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)
}