This Learn Swift series is designed for beginners with NO programming experience. It uses the latest version of Swift 3 and Xcode 8.?
1.swift的源文件擴(kuò)展名.swift
2.不需要編寫main函數(shù)，程序從上往下執(zhí)行；不需要每條語句都加分號，同一行有多條代碼語句是，中間必須有分號。
3.注釋： / 單行注釋 ? ? ? ?/* 多行注釋 */ ? ? ? 嵌套注釋 ： /* ? /* ?注釋 ?*/ ? ?*/
4.常量和變量 ? ?let聲明常量 ? ?var聲明變量
vara =1
varb =2
str="wangchao"
letf =10
str=String(29)
varc:Float=2.3
vard:Float=13.90
print(Int(c))
print(Int(d))
print(round(d))
print(round(c))
print(str)
print(a+b)
print(str)
vara =1
varb =2
str="wangchao"
letf =10
str=String(29)
varc:Float=2.3
vard:Float=13.90
print(Int(c))
print(Int(d))
print(round(d))
print(round(c))
print(str)
print(a+b)
print(str)
vara =1
varb =2
str="wangchao"
letf =10
str=String(29)
varc:Float=2.3
vard:Float=13.90
print(Int(c))
print(Int(d))
print(round(d))
print(round(c))
print(str)
print(a+b)
print(str)
vara =1
varb =2
str="wangchao"
letf =10
str=String(29)
varc:Float=2.3
vard:Float=13.90
print(Int(c))
print(Int(d))
print(round(d))
print(round(c))
print(str)
print(a+b)
var str = "Hello, playground"
var swiftString = "Swift is fun"
var hours = 24
var PI = 3.14
var me = ("Mars",26, "wangchao@163.com")
me.0
me.1
me.2
定義常量，并嘗試修改報錯
let minute = 30
//minute = 20
let不可變，要轉(zhuǎn)換成var類型
Swift根據(jù)我們賦值自動判斷變量類型? type inference，我們也可以自己指定類型
var x: Int
var s: String //指定類型? ? type annotation
5.創(chuàng)建一個button
let btn = UIButton()
btn.frame = CGRect(x:100,y:100,width:100,height:100)
btn.backgroundColor = UIColor.red
self.view.addSubview(btn)
6.整數(shù)和浮點(diǎn)數(shù)
/* 一般使用Int就行，除非有特殊情況? 如下兩種情況輸出相同，因?yàn)榫幾g器對Int進(jìn)行了正確的類型選擇*/
Int.min
Int.max
Int64.min
Int64.max
//十六進(jìn)制? 八進(jìn)制? ? 二進(jìn)制? 十進(jìn)制
let fifteenInDecimal = 15
let fifteenInHex = 0xf
let fifteenInOctal = 0o17
let fifteenInBinary = 0b1111
let million = 1_000_000 //千分位
//浮點(diǎn)數(shù)
var float1:Float = 1/3
var double1:Double = 1/3
//科學(xué)計數(shù)法
var pi = 31415926e-7
