Xcode 8, Swift 3从应用程序包中读取文件的方法:

if let path = Bundle.main.path(forResource: filename, ofType: nil) {
    do {
        let text = try String(contentsOfFile: path, encoding: String.Encoding.utf8)
        print(text)
    } catch {
        printError("Failed to read text from \(filename)")
    }
} else {
    printError("Failed to load file from app bundle \(filename)")
} 

这是一个方便的复制和粘贴扩展

public extension String {
    func contentsOrBlank()->String {
        if let path = Bundle.main.path(forResource:self , ofType: nil) {
            do {
                let text = try String(contentsOfFile:path, encoding: String.Encoding.utf8)
                return text
                } catch { print("Failed to read text from bundle file \(self)") }
        } else { print("Failed to load file from bundle \(self)") }
        return ""
    }
    }

例如

let t = "yourFile.txt".contentsOrBlank()

你几乎总是想要一个行数组:

let r:[String] = "yourFile.txt"
     .contentsOrBlank()
     .characters
     .split(separator: "\n", omittingEmptySubsequences:ignore)
     .map(String.init)

你可能会发现这个工具不仅可以从Swift中读取文件，还可以解析你的输入:https://github.com/shoumikhin/StreamScanner

只需要像这样指定文件路径和数据分隔符:

import StreamScanner

if let input = NSFileHandle(forReadingAtPath: "/file/path")
{
    let scanner = StreamScanner(source: input, delimiters: NSCharacterSet(charactersInString: ":\n"))  //separate data by colons and newlines

    while let field: String = scanner.read()
    {
        //use field
    }
}

希望这有帮助。

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

我只想给你们看第一部分，也就是阅读部分。以下是简单的阅读方法:

斯威夫特3:

let s = try String(contentsOfFile: Bundle.main.path(forResource: "myFile", ofType: "txt")!)

斯威夫特2:

let s = try! String(contentsOfFile: NSBundle.mainBundle().pathForResource("myFile", ofType: "txt")!)

写入ViewDidLoad

var error: NSError?
var paths = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, NSSearchPathDomainMask.UserDomainMask, true)
var documentsDirectory = paths.first as String
var dataPath = documentsDirectory.stringByAppendingPathComponent("MyFolder")

if !NSFileManager.defaultManager().fileExistsAtPath(dataPath) {
    NSFileManager.defaultManager().createDirectoryAtPath(dataPath, withIntermediateDirectories: false, attributes: nil, error: &error)
} else {
    println("not creted or exist")
}

func listDocumentDirectoryfiles() -> [String] {
    if let documentDirectory = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true).first as? String {
        let myFilePath = documentDirectory.stringByAppendingPathComponent("MyFolder")
        return NSFileManager.defaultManager().contentsOfDirectoryAtPath(myFilePath, error: nil) as [String]
    }
    return []
}

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
    }
}