file-io – 从文本文件读取和写入数据

概述我需要读/写一个文本文件的数据，但我还没有能够弄清楚如何。 我在Swift的iBook中找到了这个示例代码，但我还是不知道如何写或读数据。 import Cocoaclass DataImporter{ /* DataImporter is a class to import data from an external file. The class is assum 我需要读/写一个文本文件的数据，但我还没有能够弄清楚如何。

我在Swift的iBook中找到了这个示例代码，但我还是不知道如何写或读数据。

import Cocoaclass Dataimporter{    /*    Dataimporter is a class to import data from an external file.    The class is assumed to take a non-trivial amount of time to initialize.    */    var filename = "data.txt"    // the Dataimporter class would provIDe data importing functionality here}class DataManager{    @lazy var importer = Dataimporter()    var data = String[]()    // the DataManager class would provIDe data management functionality here}let manager = DataManager()manager.data += "Some data"manager.data += "Some more data"// the Dataimporter instance for the importer property has not yet been created”println(manager.importer.filename)// the Dataimporter instance for the importer property has Now been created// prints "data.txt”var str = "Hello World in Swift Language."

对于读写，应该使用可写的位置，例如文档目录。以下代码显示如何读取和写入一个简单的字符串。你可以在 *** 场上测试它。

Swift 1.x

let file = "file.txt"if let dirs : [String] = NSSearchPathForDirectorIEsInDomains(NSSearchPathDirectory.documentDirectory,NSSearchPathDomainMask.AllDomainsMask,true) as? [String] {    let dir = dirs[0] //documents directory    let path = dir.stringByAppendingPathComponent(file);    let text = "some text"    //writing    text.writetofile(path,atomically: false,enCoding: NSUTF8StringEnCoding,error: nil);    //reading    let text2 = String(contentsOffile: path,error: nil)}

Swift 2.2

let file = "file.txt" //this is the file. we will write to and read from itlet text = "some text" //just a textif let dir = NSSearchPathForDirectorIEsInDomains(NSSearchPathDirectory.documentDirectory,true).first {    let path = NSURL(fileURLWithPath: dir).URLByAppendingPathComponent(file)    //writing    do {        try text.writetoURL(path,enCoding: NSUTF8StringEnCoding)    }    catch {/* error handling here */}    //reading    do {        let text2 = try Nsstring(contentsOfURL: path,enCoding: NSUTF8StringEnCoding)    }    catch {/* error handling here */}}

Swift 3.0

let file = "file.txt" //this is the file. we will write to and read from itlet text = "some text" //just a textif let dir = fileManager.default.urls(for: .documentDirectory,in: .userDomainMask).first {    let path = dir.appendingPathComponent(file)    //writing    do {        try text.write(to: path,enCoding: String.EnCoding.utf8)    }    catch {/* error handling here */}    //reading    do {        let text2 = try String(contentsOf: path,enCoding: String.EnCoding.utf8)    }    catch {/* error handling here */}}

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