Swift4.0 字符串常用详解

最近突击了几天Swift 然后整理了一下练习的笔记

var str = "Hello"

var aa = 2.98

aa = 3

print(aa)

var optionalInteger : Int?

optionalInteger = nil

print(optionalInteger)

var stringA = ""

if stringA.isEmpty {

    print( "stringA 是空的" )

} else {

    print( "stringA 不是空的" )

}

// stringA 可被修改

var stringAV = "哈哈哈："

stringAV += "www.xigoubao.com";

print( stringAV )

//let stringB = String("菜鸟教程：")

//stringB += "www.xigoubao.com";

//print( stringB )

//Swift 字符串的长度

var varA   = "www.xigoubao.com";

print( "\(varA), 长度为 \(varA.characters.count)" )

//Swift 判断字符串的类型

let myString: String = "256"

let myInt: Int? = Int(myString)

let description=CFCopyTypeIDDescription(CFGetTypeID(myInt as CFTypeRef))//判断基础类型

print("type = \(String(describing: description))")

//判断字符串的是否含有某个后缀

let stringAA = "123.jpg"

let stringBB = stringAA.hasSuffix("jpg")

print(stringBB)

//判断字符串是否含有某个前缀

let stringCC = "www.baidu.com";

let stringDD = stringCC.hasPrefix("www")

//字符串是否包含子字符串

let stringEE = "nihaoyaxigougouhahaha"

if stringEE.contains("xigou") {

    print("公司产品")

}else

{

   

    print("NONONONO")

}

let stringFF = "nihaoyaxigougouhahaha"

//判断字符串是否相等

if stringEE==stringFF {

    print("no")

}else

{

    print("yes")

}

//拼接字符串

print(stringFF+"====="+stringEE)