<span style="font-family: Arial,Helvetica,sans-serif; background-color: rgb(255,255,255);">如果你看到这篇文章，说明你有学IOS开的的强烈愿望。</span>
我很高兴为你讲解我的学习过程。首先，你会问为什么不选择ObjC而是Swift，我想这个问题只有苹果自己知道，我们只有猜。不过从代码结构上来看Swift确实比OC简洁多了，Swift省掉那些OC难以理解的符号，比如NSLog传递消息时是这么写的：NSLog(@"You code in here"); 学过C#的Programmer应该认识这个@，在OC中我不知道怎么理解，所以就不管了。
那么现在我们就开始，yeah！首先，我强烈建议去买台MAC，也就一万左右。当然，如果你和我一样用的是咱们中国人撑起的Windows，你可以和我一样装个虚拟就OK了。我的虚拟机是：VMware Workstation 12.1.0 ＋ OS X EI Capitan 10.11.2，请原谅我是一个强迫症患者，任何软件都要最新的。
关于如何安装XCode 7.2我就不说了，你去AppStore免费下就OK了！
注：我的笔记都以注释的方式在源码中呈现！！！
学习笔记开始
//
// main.swift
// hello word
//
// Created by YiSong on 12/10/15.
// copyright © 2015 YiSong. All rights reserved.
//
import Foundation
print("------------Hello Word!-----------\n")
// Variable 'number' used before being initialized.
var number: Int?
var number2: Int = 100
number = 888
print(number)
print(number2)
/**
* End of every statement have a semicolon.
*/
let mConstant = 9;
var mVariable = 1;
mVariable = 6;
print("Print mVarible and mConstant in string,mVarible:\(mVariable) mConstant:\(mConstant) \n");
/**
* End of every statement without semicolon.
*/
let label = "The width is"
let width = 94
let widthLabel = label + " " + String(width)
print(label)
print(widthLabel + "\n")
/**
* Create arrays and dictionaries using barckets([]).
*/
var shoppingList = ["catfish","water","tulips","bulepaint"];
shoppingList[1] = "apple";
print(shoppingList);
// you should notice,print() method can output a array.
var occupations = [
"Malcolm" : "Captain","Kaylee" : "Mechainc",];
occupations["Kaylee"] = "";
occupations["Jayne"] = "Public Relations";
print(occupations);
print("\n");
/**
* Create an empty array or dictionary,use the initializer Syntax.
*/
var emptyStringArray = [String]()
let emptyIntegerArray = [Int]()
var emptyDictionary = [String : Double]()
emptyStringArray.append("I'm append")
print(emptyStringArray)
emptyDictionary["price"] = 21.00
print(emptyDictionary)
var carList = []
var studentInfo = [:]
carList = emptyStringArray
print(carList)
studentInfo = emptyDictionary
print(studentInfo)
var optionalString: String? = "hello"
print(optionalString == nil)
// you should notice,keyword nil is equal to null.
var optionalName: String? = "John Applseed"
var greeting = "Hello!"
if let name = optionalName {
greeting = "Hello,\(name)"
}
print(greeting)
let nickName: String? = nil
let fullName = "John Appelseed"
let infomalGreetin1 = "Hi \(nickName ?? fullName)"
let infomalGreetin2 = "Hi \(nickName != nil ? nickName :fullName)"
print(infomalGreetin1)
print(infomalGreetin2)
// switch
let vegetable = "red pepper"
switch vegetable{
case "celery":
print("Add some raisins and make ants on a log.")
// case "cucumber","watercress","red pepper":
// print("That would make a good tea sandwich.")
case let x where x.hasSuffix("pepper"):
print("Is it a sicpy \(x)")
default:// Switch must be exhaustive,consider adding a default clause.
print("Evertthing tastes good in soup.")
}
let interestingNumbers = [
"Prime" : [2,3,4,5,6,7],"Fibonacci" : [1,1,2,0],"Square" : [3,44,55,2]
]
var largest = 0
// for-in
for (kind,numbers) in interestingNumbers{
print(kind)
print(numbers)
for number in numbers{
//print(number)
if (number > largest){
largest = number
}
}
}
print("The largest number is \(largest)")
// while
var m = 0
while (m < 0){
m += 1;
}
print(m)
// repeat-while like do-while in other program language.
var n = 0;
repeat{
n += 1;
}while n < 0
print(n)
// using ..< to make a range.
var sum = 0
for i in 0..<10 {
sum += i
}
print(sum)
sum = 0
for (var i = 0; i<10 ;i++) {
sum += i
}
print(sum)
// use func to declare a function. use -> to separate the parameter names and types from the function's return type.
func greet(name : String,age : Int) -> String{
return "Hello \(name),your age is \(age)"
}
print(greet("YiSong",age: 22))
// use a truple to make a compound value - for example,to return multiple values from a function. The elements of a tuple can be rither by name or by number.
func calculateStatistics(scores : [Int]) -> (min : Int,max : Int,sum : Int,average: Float){
var min = scores[0]
var max = scores[0]
var sum = 0
var average: Float
for score in scores{
if score < min{
min = score
}
if score > max{
max = score
}
sum += score
}
average = Float(sum)/Float(scores.count)
return (min,max,sum,average)
}
// print(calculateStatistics([66,78,90,45,70,98,88,69,58]))
let statistics = calculateStatistics([66,58])
print("min score: \(statistics.min),max score: \(statistics.1),sum score:\(statistics.sum),average score:\(statistics.average))")
// Functions can also take a variable number of argument,collecting them into an array
func sumOf (numbers: Int...) -> Int{
var sum = 0
for number in numbers{
sum += number
}
return sum
}
print(sumOf())
print(sumOf(23,56,67,90))
// functions are first-class type. This means that a funxtion can return another function as its value.
func makeIncrementer() -> ((Int) -> Int){
func addOne(number: Int) -> Int{
return number + 1;
}
return addOne
}
print(makeIncrementer()(8))
// A function can take another function as one of its arguments.
func hasAnyMatches(list: [Int],condition: (Int) -> Bool) -> (isMatche: Bool,list: [Int]){
var isMatche: Bool = false
var lessthanTenList: [Int] = []
for item in list{
if condition(item){
isMatche = true
lessthanTenList.append(item)
}
}
return (isMatche,lessthanTenList)
}
func lessthanTen(number: Int) -> Bool{
return number < 10
}
var result = hasAnyMatches([20,34,12],condition: lessthanTen)
print(result.isMatche)
print(result.list)
// closure
var numbers = [22,33,55]
print(numbers.map({
(number: Int) -> Int in
let result = 3 * number
return result
}))
print(numbers.map({ number in 3 * number}))
// rewrite the closure to return zero for odd numbers
func isOddNumber(number: Int) -> Bool{
return number % 2 == 0 ? false : true
}
print(numbers.map({ (number: Int) -> Int in
if isOddNumber(number){
return 0
}else{
return number
}
}))
//When a closure is the only argument to a function,you can omit the parentheses entirely.
print(numbers.sort{ $0 > $1})