swift中string字符串的使用

// 字符串的定义
// 1 使用字符串字面量
var name = "DevZhang"
print(name)
// 2 String 实例化
name = String("Hello,DevZhang")
print(name)

// 字符串追加字符串
name = name + ".where are you from?"
print(name)

// 是否包含子串
let range = name.rangeOfString("DevZhang")
if range != nil
{
 print(range)
            
 let indexStart = range!.startIndex
 let indexEnd = range!.endIndex
 let indexLength = 0 // indexEnd - indexStart
 print("index start = (indexStart),end = (indexEnd),length = (indexLength)")
}
else
{
 print("不包含")
}

// 截取子字符串substring
name = name.substringFromIndex(name.startIndex.advancedBy(4))
print(name)
name = name.substringToIndex(name.startIndex.advancedBy(30))
print(name)
let rangeName = Range<String.Index>(start: name.startIndex.advancedBy(1),end: name.endIndex.advancedBy(-1))
name = name.substringWithRange(rangeName)
print(name)

// 字符串修剪trim
let str011 = "DevZhang.n "
print(str011)
let str012 = str011.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceAndNewlineCharacterSet())
print(str012)
// 去掉空格
let str013 = str011.stringByTrimmingCharactersInSet(NSCharacterSet.whitespaceCharacterSet())
print(str013)
let charset014 = NSCharacterSet(charactersInString:" n")
let str015 = str011.stringByTrimmingCharactersInSet(charset014)
print(str015)

// 字符串替换replace（当withString为空字符串时，相当于删除）
var str031 = "My name is DevZhang"
let rangeReplace = Range(start: str031.startIndex,end: str031.startIndex.advancedBy(2))
str031.replaceRange(rangeReplace,with: "Your")
print(str031)
var str032 = "hello,DevZhang."
str032 = str032.stringByReplacingOccurrencesOfString("DevZhang",withString: "zhangshaoyu")
print(str032)
str032 = str032.stringByReplacingOccurrencesOfString("zhangshaoyu",withString: "DevZhang",options: NSStringCompareOptions.CaseInsensitiveSearch,range: nil)
print(str032)

// 字符串删除指定字符串
var str041 = "My name is DevZhang,your name is DevTang"
print(str041)
// let rangeRemove = Range<String.Index>str041.rangeOfString("DevZhang")
// str041.removeRange(rangeRemove)
str041 = str041.stringByReplacingOccurrencesOfString("DevTang",withString: "")
print(str041)

// 首字母大写
name = name.capitalizedString
print(name)

// 字符串小写转换大写
name = name.uppercaseString
print(name)

// 字符串大写转换小写
name = name.lowercaseString
print(name)

// 字符串长度
let lengthName = name.characters.count
print("(name) 的长度是 (lengthName)")

// Unicode编码
for codeUTF8 in name.utf8
{
 print("(codeUTF8) ")
}
print("")
for codeUTF16 in name.utf16
{
 print("(codeUTF16) ")
}

// 字符串的非空判断
let isEmptyName:Bool = name.isEmpty
if isEmptyName
{
 print("name is nill")
}
else
{
 print("name is no nil")
}

// 字符串前缀
if name.hasPrefix("Hello")
{
 print("有对应的 Hello 前缀")
}
else
{
 print("没有对应的 Hello 前缀")
}

// 字符串后缀
if name.hasSuffix("from")
{
 print("有对应的 from 后缀")
}
else
{
 print("没有对应的 from 后缀")
}

// 字符串比较
let varA   = "Hello,Swift!"
let varB   = "Hello,Objective-C!"
        
// 比较字符串是否相等
if varA == varB
{
 print("(varA) 与 (varB) 是相等的")
}
else
{
 print("(varA) 与 (varB) 是不相等的")
}
        
// 比较字符串是否不相等
if varA != varB
{
 print("(varA) 与 (varB) 不相等")
}
else
{
 print("(varA) 与 (varB) 相等")
}
        
// 比较字符串的大小（两个字符串的字母逐一比较）
if varA > varB
{
 print("(varA) 大于 (varB)")
}
else
{
 print("(varA) 小于 (varB)")
}

// 数值型字符串转换成Int/Long/Float/Double/Bool等（注意：转换值必须添加optional选项" ! "，或" ? "）
let moneyStr:String = String("3025.56")
let moneyNum01:Float! = Float(moneyStr)
print(moneyNum01)
let moneyNum02:Double! = (moneyStr as NSString).doubleValue
print(moneyNum02)
let moneyNum03:String = "1000"
let moneyNum04:Int32 = (moneyNum03 as NSString).intValue
print(moneyNum04)
let valid:String = "true"
let isValid:Bool! = (valid as NSString).boolValue
print(isValid)

// 字符（注意：字符中只能有一个字符，不能有两个及以上）
let charA:Character = "A"
print(charA)
        
// 字符转换成字符串
name = String(charA)
print(name)
        
// 获取字符串中指定索引处的字符
let charName = name[name.startIndex]
print(charName)
        
// 字符串转换成字符
for charTmp in valid.characters
{
 print("char = (charTmp)")
}
        
// 字符串添加字符
name.append(charA)
print(name)
name = String("(name)(charA)")
print(name)

// 字符串的分解子串split，即转换成数组
let str021 = "boy,girl,man,woman"
print(str021)
let str021Array = str021.componentsSeparatedByString(",")
print(str021Array)
let str022 = "boy,man 10 20 30"
print(str022)
let charset023 = NSCharacterSet(charactersInString:",")
print(charset023)
let str022Array = str022.componentsSeparatedByCharactersInSet(charset023)
print(str022Array)

// 字符串转换成NSData
var str061:String = "String to encode data"
print(str061)
let data = str061.dataUsingEncoding(NSUTF8StringEncoding)
print(data)

（编辑：李大同）

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