新的更简单和推荐的方法: 苹果建议使用url进行文件处理，这里的其他解决方案似乎已被弃用(见下面的评论)。 下面是新的简单的读写URL的方法:

Swift 5+， 4和3.1

import Foundation  // Needed for those pasting into Playground

let fileName = "Test"
let dir = try? FileManager.default.url(for: .documentDirectory, 
      in: .userDomainMask, appropriateFor: nil, create: true)

guard let fileURL = dir?.appendingPathComponent(fileName).appendingPathExtension("txt") else {
    fatalError("Not able to create URL")
}
    
// Writing to the file named Test
let outString = "Write this text to the file"
do {
    try outString.write(to: fileURL, atomically: true, encoding: .utf8)
} catch {
    assertionFailure("Failed writing to URL: \(fileURL), Error: " + error.localizedDescription)
}
    
// Reading it back from the file
var inString = ""
do {
    inString = try String(contentsOf: fileURL)
} catch {
    assertionFailure("Failed reading from URL: \(fileURL), Error: " + error.localizedDescription)
}
print("Read from the file: \(inString)")

 func writeToDocumentsFile(fileName:String,value:String) {
    let documentsPath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0] as NSString
    let path = documentsPath.appendingPathComponent(fileName)
    do{
    try value.write(toFile: path, atomically: true, encoding: String.Encoding.utf8)
}catch{
    }
    }

func readFromDocumentsFile(fileName:String) -> String {
    let documentsPath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0] as NSString
    let path = documentsPath.appendingPathComponent(fileName)
    let checkValidation = FileManager.default
    var file:String

    if checkValidation.fileExists(atPath: path) {
        do{
       try file = NSString(contentsOfFile: path, encoding: String.Encoding.utf8.rawValue) as String
        }catch{
            file = ""
        }
        } else {
        file = ""
    }

    return file
}

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。

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)

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")!)

这适用于Linux上的Swift 3.1.1:

import Foundation

let s = try! String(contentsOfFile: "yo", encoding: .utf8)