斯威夫特3。X - 5.x

最好的例子是创建一个扩展名为.txt的本地日志文件 可以在“文件应用程序”中显示当前日期和时间作为文件名

只需在信息中添加此代码。请启用这两个功能

  UIFileSharingEnabled
  LSSupportsOpeningDocumentsInPlace

和下面的函数

var logfileName : String = ""

func getTodayString() -> String{

    let date = Date()
    let calender = Calendar.current
    let components = calender.dateComponents([.year,.month,.day,.hour,.minute,.second], from: date)

    let year = components.year
    let month = components.month
    let day = components.day
    let hour = components.hour
    let minute = components.minute
    let second = components.second

    let today_string = String(year!) + "-" + String(month!) + "-" + String(day!) + "-" + String(hour!)  + "" + String(minute!) + "" +  String(second!)+".txt"

    return today_string

}

func LogCreator(){
    logfileName = getTodayString()

    print("LogCreator: Logfile Generated Named: \(logfileName)")

    let file = logfileName //this is the file. we will write to and read from it

    let text = "some text" //just a text

    if let dir = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first {

        let fileURL = dir.appendingPathComponent(file)
        let documentPath = NSSearchPathForDirectoriesInDomains(.documentDirectory,.userDomainMask, true)[0]
        print("LogCreator: The Logs are Stored at location \(documentPath)")


        //writing
        do {
            try text.write(to: fileURL, atomically: false, encoding: .utf8)
        }
        catch {/* error handling here */}

        //reading
        do {
            let text2 = try String(contentsOf: fileURL, encoding: .utf8)
            print("LogCreator: The Detail log are :-\(text2)")
        }
        catch {/* error handling here */}
    }
}


  [1]: https://i.stack.imgur.com/4eg12.png

为了避免混淆并增加易用性，我创建了两个函数，用于向documents目录中的文件读取和写入字符串。功能如下:

func writeToDocumentsFile(fileName:String,value:String) {
    let documentsPath = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0] as! NSString
    let path = documentsPath.stringByAppendingPathComponent(fileName)
    var error:NSError?
    value.writeToFile(path, atomically: true, encoding: NSUTF8StringEncoding, error: &error)
}

func readFromDocumentsFile(fileName:String) -> String {
    let documentsPath = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0] as! NSString
    let path = documentsPath.stringByAppendingPathComponent(fileName)
    var checkValidation = NSFileManager.defaultManager()
    var error:NSError?
    var file:String

    if checkValidation.fileExistsAtPath(path) {
        file = NSString(contentsOfFile: path, encoding: NSUTF8StringEncoding, error: nil) as! String
    } else {
        file = "*ERROR* \(fileName) does not exist."
    }

    return file
}

下面是一个使用它们的例子:

writeToDocumentsFile("MyText.txt","Hello world!")

let value = readFromDocumentsFile("MyText.txt")
println(value)  //Would output 'Hello world!'

let otherValue = readFromDocumentsFile("SomeText.txt")
println(otherValue)  //Would output '*ERROR* SomeText.txt does not exist.'

希望这能有所帮助!

Xcode版本:6.3.2

假设你已经将你的文本文件data.txt移动到你的Xcode-project中(使用拖放并勾选“必要时复制文件”)，你可以像在Objective-C中一样执行以下操作:

let bundle = NSBundle.mainBundle()
let path = bundle.pathForResource("data", ofType: "txt")        
let content = NSString.stringWithContentsOfFile(path) as String

println(content) // prints the content of data.txt

更新: 对于从Bundle (iOS)读取文件，您可以使用:

let path = NSBundle.mainBundle().pathForResource("FileName", ofType: "txt")
var text = String(contentsOfFile: path!, encoding: NSUTF8StringEncoding, error: nil)!
println(text)

Swift 3更新:

let path = Bundle.main.path(forResource: "data", ofType: "txt") // file path for file "data.txt"
var text = String(contentsOfFile: path!, encoding: NSUTF8StringEncoding, error: nil)!

Swift 5

let path = Bundle.main.path(forResource: "ListAlertJson", ofType: "txt") // file path for file "data.txt"
let string = try String(contentsOfFile: path!, encoding: String.Encoding.utf8)

对于我的txt文件是这样工作的:

let myFileURL = NSBundle.mainBundle().URLForResource("listacomuni", withExtension: "txt")!
let myText = try! String(contentsOfURL: myFileURL, encoding: NSISOLatin1StringEncoding)
print(String(myText))

Xcode 8.3.2 Swift 3.x。使用NSKeyedArchiver和NSKeyedUnarchiver

从文档中读取文件

let documentsDirectoryPathString = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true).first!
let documentsDirectoryPath = NSURL(string: documentsDirectoryPathString)!
let jsonFilePath = documentsDirectoryPath.appendingPathComponent("Filename.json")

let fileManager = FileManager.default
var isDirectory: ObjCBool = false

if fileManager.fileExists(atPath: (jsonFilePath?.absoluteString)!, isDirectory: &isDirectory) {

let finalDataDict = NSKeyedUnarchiver.unarchiveObject(withFile: (jsonFilePath?.absoluteString)!) as! [String: Any]
}
else{
     print("File does not exists")
}

将文件写入文档

NSKeyedArchiver.archiveRootObject(finalDataDict, toFile:(jsonFilePath?.absoluteString)!)

早期的解决方案回答了问题，但在我的情况下，删除文件的旧内容而写入是一个问题。

所以，我创建了一段代码写入文件目录中的文件，而不删除以前的内容。您可能需要更好的错误处理，但我相信这是一个很好的起点。斯威夫特4。 Usuage:

    let filename = "test.txt"
    createOrOverwriteEmptyFileInDocuments(filename: filename)
    if let handle = getHandleForFileInDocuments(filename: filename) {
        writeString(string: "aaa", fileHandle: handle)
        writeString(string: "bbb", fileHandle: handle)
        writeString(string: "\n", fileHandle: handle)
        writeString(string: "ccc", fileHandle: handle)
    }

辅助方法:

func createOrOverwriteEmptyFileInDocuments(filename: String){
    guard let dir = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first else {
        debugPrint("ERROR IN createOrOverwriteEmptyFileInDocuments")
        return
    }
    let fileURL = dir.appendingPathComponent(filename)
    do {
        try "".write(to: fileURL, atomically: true, encoding: .utf8)
    }
    catch {
        debugPrint("ERROR WRITING STRING: " + error.localizedDescription)
    }
    debugPrint("FILE CREATED: " + fileURL.absoluteString)
}

private func writeString(string: String, fileHandle: FileHandle){
    let data = string.data(using: String.Encoding.utf8)
    guard let dataU = data else {
        debugPrint("ERROR WRITING STRING: " + string)
        return
    }
    fileHandle.seekToEndOfFile()
    fileHandle.write(dataU)
}

private func getHandleForFileInDocuments(filename: String)->FileHandle?{
    guard let dir = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first else {
        debugPrint("ERROR OPENING FILE")
        return nil
    }
    let fileURL = dir.appendingPathComponent(filename)
    do {
        let fileHandle: FileHandle? = try FileHandle(forWritingTo: fileURL)
        return fileHandle
    }
    catch {
        debugPrint("ERROR OPENING FILE: " + error.localizedDescription)
        return nil
    }
}