Swift 基本常量和变量,基本数据类型
//: Playground - noun: a place where people can play
import UIKit
var str = "Hello, playground"
//常量 let
let maxNum = 1000
//maxNum = 2000
//变量 var
var index = 2
index = 3
var x = 1, y = 2, z = 3
//Type inference
//x = "Hello"
var s = "Hello"
let webSite: String = "www.imcooc.com"
//整型
var imIntt: Int = 80
Int.max
Int.min
var imUInt: UInt = 50
UInt.max
UInt.min
UInt8.max
UInt8.min
UInt32.max
UInt32.min
Int64.max
Int64.min
//浮点数
let imFloat:Float = 3.1415927
let imDouble:Double = 3.1415926
var a = 1.25e10
var b = 1.25e-8
//不同类型转换
let x: UInt16 = 100
let y: UInt8 = 20
//x+y//swif不能自动转换类型
let m = x + UInt16(y)//必须类型强制转换
let a:Double = 3.0
let b:Float = 0.3
a + Double(b)
Float(a) + b
let w: Float = 3
let v:Int = Int(3.2)
let integer = 3
let fraction = 0.1415926
let pi = Double(integer) + fraction
let red:CGFloat = 0.2
let green:CGFloat = 0.5
let blue:CGFloat = 0.5
UIColor(red: red, green: green, blue: blue, alpha: 1)
let imTure: Bool = true
let imFalse = false
if imTure {
print("I'm True")
} else if 3 + 4 == 7 {
print("3 + 4 == 7")
}
else {//会出现警告，代码冗余（不会被执行）
print("I'm False")
}
//if 1 {//不可以这样写，整型和布尔值不能混合使用
// print("True")
//}
let a = 1
if a == 1 {
print("True")
}
元组
var point = (5, 2)
var httpResponse = (404 , "Not Found ")
var point2: (Int , Int , Int) = (10, 5, 2)
var httpResponse2:(Int, String) = (200, "OK")
//元组使用
let (x, y) = point
x
y
var (statusCode ,statusMessage) = httpResponse
statusCode
statusMessage
statusCode = 405
point.0
point.1
let point3 = (x:3, y:4)
point3.x
point3.y
let point4: (x:Int, y:Int) = (10,5)
point4.x
point4.y
let loginResult = (true, "liuyubobobo")
let (isloginSuccess, _) = loginResult//获取第一个参数，不需要第二个参数用_代替
if isloginSuccess {
print("Login success !")
}
else {
print("Login failed !")
}
//String 字符类型
//使用双引号
var 名字 = "liuyubobobo"
print("我的名字是" + 名字)
//print 函数
let x = 1, y = 2, z = 3, b = true
print(x, y, z, b)
print(x, y, z, separator: ",")//separator 打印的信息分割符（相当于空格）
print(x, y, z, separator: "--")
print(x, y, z, separator: "--", terminator: ":)")//terminator 相当于回车
print("Hello")
print(y , "*", z, "=", y*z)
print("\(y) * \(z) = \(y*z)")
//注释
/**/ //多行注释
= "www.imcooc.com"
