String Programming Guide

String是一系列char数据的集合，如”hello,world”或”albatross”。它是苹果公司针对Swift语言编写的管理字符串的对象。String以优雅的方式结合了NSString和NSMutableString的优点，并简化了接口的使用。本文介绍了关于String日常开发过程中的一系列方法，供大家查阅。

类型别名

// MARK: 类型别名
private func testTypeAliases() {

    let index = String.Index.self
    print("\(index)")

    let utf8index = String.UTF8Index.self
    print("\(utf8index)")

    let utf16index = String.UTF16Index.self
    print("\(utf16index)")

    let unicodeScalarIndex = String.UnicodeScalarIndex.self
    print("\(unicodeScalarIndex)")

    let greeting = "Guten Tag!"
    greeting[greeting.startIndex] // G
    greeting[greeting.endIndex.predecessor()] // !
    greeting[greeting.startIndex.successor()] // u
    greeting[greeting.startIndex.advancedBy(7)] // a

}

初始化

// MARK: 初始化
private func testInitializers() {
    // 空字符串
    var string:String = String()
    string = ""

    // char初始化
    let char: Character = "阳"
    string = String(char)
    string = String.init(char)
    string = "\(char)"

    // 通过CharacterView
    let charView:String.CharacterView = String.CharacterView("阳君")
    string = String(charView);

    // 通过UTF-16编码
    let utf16:String.UTF16View = string.utf16
    string = String(utf16)

    // 通过UTF-8编码
    string = String(string.utf8)

    // 多个字符串组合生成
    string = String(stringInterpolation: "阳君","937447974")

    // char初始化，连续count次
    string = String(count: 3,repeatedValue: char)

    // 通过其他常用数据初始化
    string = String(stringInterpolationSegment: true)
    string = String(stringInterpolationSegment: 24)


    // 通过NSString初始化,不推荐
    // 通过字符串生成字符串
    string = NSString(string: "阳君") as String
    string = NSString.init(string: "阳君") as String

    // 组合生成
    string = NSString(format: "%@","阳君") as String

    print("\(string)")
}

文件路径操作

// MARK: - 文件路径操作
private func testWorkingWithPaths() {
    var path = "IOS/Swift"
    // 路径分割成数组
    var pathComponents = (path as NSString).pathComponents

    // 数组组合成路径
    path = NSString.pathWithComponents(pathComponents)

    // Document目录
    let documents:[String] = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory,NSSearchPathDomainMask.UserDomainMask,true)
    let docDirPath = documents.first!
    // 寻找文件夹下包含多少个路径
    var complete = docDirPath.completePathIntoString(caseSensitive: true)
    // 寻找文件夹下包含指定扩展名的文件路径
    var outName = ""
    let filterTypes = ["txt","plist"]
    complete = docDirPath.completePathIntoString(&outName,caseSensitive: true,matchesIntoArray: &pathComponents,filterTypes: filterTypes)
    print("completePathIntoString:\(complete)")

    // 添加路径
    path = (docDirPath as NSString).stringByAppendingPathComponent("test")
    // 添加扩展
    path = (path as NSString).stringByAppendingPathExtension("plist")!

    print("是否绝对路径:\((path as NSString).absolutePath)")
    print("最后一个路径名:\((path as NSString).lastPathComponent)")
    print("扩展名:\((path as NSString).pathExtension)")

    // 去掉扩展名
    var tempPath:Any = (path as NSString).stringByDeletingPathExtension
    // 去掉最后一个路径
    tempPath = (path as NSString).stringByDeletingLastPathComponent
    print("\(tempPath)")

    // 转%格式码
    let allowedCharacters:NSCharacterSet = NSCharacterSet.controlCharacterSet()
    tempPath = path.stringByAddingPercentEncodingWithAllowedCharacters(allowedCharacters)

    // 转可见
    tempPath = path.stringByRemovingPercentEncoding

}

文件读写操作

// MARK: 文件读写操作
private func testFile() {

    var string = "阳君；937447974"

    // Document目录
    let documents:[String] = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory,true)
    let docDirPath = documents.first!
    let filePath = (docDirPath as NSString).stringByAppendingPathComponent("test.plist")
    let fileUrl = NSURL(fileURLWithPath: filePath)

    do {
        // 写入
        try string.writeToFile(filePath,atomically: true,encoding: NSUTF8StringEncoding)
        try string.writeToURL(fileUrl,encoding: NSUTF8StringEncoding)

        // 读取
        // 自动解析
        try string = String(contentsOfFile: filePath)
        // 指定编码解析
        try string = String(contentsOfFile: filePath,encoding: NSUTF8StringEncoding)
        // 使用默认的编码解析，如果不能解析，采取默认解析并返回解析编码
        var encoding:NSStringEncoding = NSUTF16LittleEndianStringEncoding
        try string = String(contentsOfFile: filePath,usedEncoding: &encoding)

        // URl 读取
        try string = String(contentsOfURL: fileUrl)
        try string = String(contentsOfURL: fileUrl,encoding: NSUTF8StringEncoding)
        try string = String(contentsOfURL: fileUrl,usedEncoding: &encoding)
    } catch {
        print("错误:\(error)")
    }

}

获取字符串的Swift属性

// MARK: - 获取字符串的Swift属性
private func testGettingProperties() {
    let string = String(stringInterpolation: "阳君","y;j","937447974")

    // String.CharacterView
    print("String.CharacterView:\(string.characters)")

    // String.UnicodeScalarView
    print("String.UnicodeScalarView:\(string.unicodeScalars)")

    // String.UTF16View
    print("String.UTF16View:\(string.utf16)")

    // String.UTF8View
    print("String.UTF8View:\(string.utf8)")

    // hash值
    print("hashValue:\(string.hashValue)")

    // 是否为空
    print("isEmpty:\(string.isEmpty)")
}

获取字符串长度

// MARK: 获取字符串长度
private func testGettingLength() {
    let string = "阳君；937447974"
    // 起始位置
    var index =  string.startIndex
    // 结束位置
    index = string.endIndex
    print("\(index)")
    // NSString方式获取长度
    var length = (string as NSString).length
    print("\(length)")
    // 通过编码获取长度
    length = string.lengthOfBytesUsingEncoding(NSUTF8StringEncoding)
    // 返回存储时需要指定的长度
    length = string.maximumLengthOfBytesUsingEncoding(NSUTF8StringEncoding)
}

大小写变化

// MARK: - 大小写变化
private func testChangingCase() {
    let str = "阳君;y937447974J"
    // 大写和小写
    print("uppercaseString:\(str.uppercaseString);lowercaseString:\(str.lowercaseString)")
}

得到数值

// MARK: 得到数值
private func testGettingNumericValues() {
    let string = "24"
    let nStr = string as NSString // 借用NSString输出
    print("doubleValue:\(nStr.doubleValue)")
    print("floatValue:\(nStr.floatValue)")
    print("intValue:\(nStr.intValue)")
    print("integerValue:\(nStr.integerValue)")
    print("longLongValue:\(nStr.longLongValue)")
    print("boolValue:\(nStr.boolValue)")

}

增加字符串

// MARK: - 增加字符串
private func testCombiningStrings() {
    var str = "阳君;937447974"

    // 添加字符串
    str.appendContentsOf(";Swift")
    str += ";11"
    str.write("222")

    // string后增加字符串并生成一个新的字符串
    str = str.stringByAppendingString(str)

    // string后增加组合字符串并生成一个新的字符串
    str = str.stringByAppendingFormat(";%@","OC")

    // string后增加循环字符串，stringByPaddingToLength：完毕后截取的长度；startingAtIndex：从增加的字符串第几位开始循环增加。
    str = str.stringByPaddingToLength(30,withString:";Swift",startingAtIndex:3)

    // 指定位置插入Character
    str.insert("5",atIndex: str.endIndex.advancedBy(-1))

    // 指定位置插入字符串
    str.insertContentsOf("78".characters,at: str.startIndex.advancedBy(9))
}

分割字符串

// MARK: 分割字符串
private func testDividingStrings() {
    let str = "阳君;937447974"

    // 根据指定的字符串分割成数组
    var array = str.componentsSeparatedByString(";")

    // 通过系统自带的分割方式分割字符串
    array = str.componentsSeparatedByCharactersInSet(NSCharacterSet.lowercaseLetterCharacterSet())
    print("array\(array)")

    // 指定位置后的字符串
    var tempStr = str.substringFromIndex(str.startIndex.advancedBy(3))

    // 指定位置前的字符串
    tempStr = str.substringToIndex(str.startIndex.advancedBy(3))

    // 指定范围的字符串
    let range = str.endIndex.advancedBy(-6)..<str.endIndex
    tempStr = str.substringWithRange(range)
    print("tempStr:\(tempStr)")

}

查找字符串

// MARK: 查找字符串
private func testFindingStrings() {
    let str = "阳君;\n937447974";
    let searchRange = str.startIndex ..< str.startIndex.advancedBy(10)

    // 根据NSCharacterSet查找
    let cSet = NSCharacterSet.uppercaseLetterCharacterSet()
    var range = str.rangeOfCharacterFromSet(cSet)

    // 根据字符串查找
    range = str.rangeOfString("93")
    range = str.rangeOfString("93",options: NSStringCompareOptions.CaseInsensitiveSearch,range: searchRange,locale: nil)
    print("\(range)")

    // block 行查找
    str.enumerateLines { (line,stop) -> () in
        print("\(line)")
        if "93" == line {
            stop = true
        }
    }

    // block查找，可设置查找方式，并得到找到的位置
    str.enumerateSubstringsInRange(searchRange,options: NSStringEnumerationOptions.ByComposedCharacterSequences) { (substring,substringRange,enclosingRange,stop) -> () in
        print("\(substring)")
        if "9" == substring {
            print("\(substringRange)")
            stop = true
        }
    }

}

替换字符串

// MARK: 替换字符串
private func testReplacingSubstrings() {

    var string = "阳君;937447974"
    let replacingRange = string.startIndex ... string.startIndex.advancedBy(3)

    // 全局替换
    string = string.stringByReplacingOccurrencesOfString(";",withString: "+")
    // 设置替换的模式，并设置范围
    string = string.stringByReplacingOccurrencesOfString("+",withString: ";",options: NSStringCompareOptions.CaseInsensitiveSearch,range: replacingRange)

    //将指定范围的字符串替换为指定的字符串
    string.replaceRange(replacingRange,with: "12345")
    string = string.stringByReplacingCharactersInRange(replacingRange,withString: "12345")

}

删除字符串

// MARK: 删除字符串
private func testRemovingSubstrings() {
    var string = "阳君;937447974"
    // 删除指定位置的字符串
    string.removeAtIndex(string.startIndex.advancedBy(1))

    // 根据范围删除字符串
    let range = string.endIndex.advancedBy(-6)..<string.endIndex
    string.removeRange(range)

    // 删除所有
    string.removeAll()
    string.removeAll(keepCapacity: true)
}

比较字符串

// MARK: 比较字符串
private func testComparingStrings() {

    var string = "阳君;937447974"
    let compareStr = "阳君;837447974"
    let searchRange = string.startIndex ..< string.endIndex

    // 前缀
    var isHas = string.hasPrefix("阳君")
    print("hasPrefix:\(isHas)")

    // 后缀
    isHas = string.hasSuffix("Swift")
    print("hasSuffix:\(isHas)")

    // 全比较是否相同
    isHas = string == compareStr

    // 比较大小
    var result = string.compare(compareStr)
    // 添加比较范围
    result = string.compare(compareStr,range: searchRange,locale: nil)
    print("result:\(result)")

    // 返回两个字符串相同的前缀
    string = string.commonPrefixWithString(compareStr,options: NSStringCompareOptions.CaseInsensitiveSearch)

}

其他

参考资料

NSString Class Reference
NSMutableString Class Reference
The Swift Programming Language (Swift 2.1)
String Structure Reference

文档修改记录

时间	描述
2015-10-21	根据Swift2.1 String的API总结

String Programming Guide

类型别名

初始化

文件路径操作

文件读写操作

获取字符串的Swift属性

获取字符串长度

大小写变化

得到数值

增加字符串

分割字符串

查找字符串

替换字符串

删除字符串

比较字符串

其他

参考资料

文档修改记录

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