我需要在文本文件中读取和写入数据,但我还没有弄清楚如何。
我在Swift的iBook中找到了这个示例代码,但我仍然不知道如何编写或读取数据。
import Cocoa
class 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."
答案 0 :(得分:466)
对于读写,您应该使用可写的位置,例如文档目录。以下代码显示了如何读取和写入简单的字符串。你可以在操场上测试它。
Swift 3.x和Swift 4.0
let file = "file.txt" //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)
//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)
}
catch {/* error handling here */}
}
Swift 2.2
let file = "file.txt" //this is the file. we will write to and read from it
let text = "some text" //just a text
if let dir = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomainMask.AllDomainsMask, true).first {
let path = NSURL(fileURLWithPath: dir).URLByAppendingPathComponent(file)
//writing
do {
try text.writeToURL(path, atomically: false, encoding: NSUTF8StringEncoding)
}
catch {/* error handling here */}
//reading
do {
let text2 = try NSString(contentsOfURL: path, encoding: NSUTF8StringEncoding)
}
catch {/* error handling here */}
}
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, encoding: NSUTF8StringEncoding, error: nil)
}
答案 1 :(得分:80)
假设您已将文本文件data.txt
移至Xcode项目(使用拖动' n'删除并检查"必要时复制文件")您可以执行跟随Objective-C一样:
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:
要从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的更新:
let path = Bundle.main.path(forResource: "data", ofType: "txt") // file path for file "data.txt"
var text = String(contentsOfFile: path!, encoding: NSUTF8StringEncoding, error: nil)!
答案 2 :(得分:68)
Xcode 8.x•Swift 3.x或更高版本
do {
// get the documents folder url
if let documentDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first {
// create the destination url for the text file to be saved
let fileURL = documentDirectory.appendingPathComponent("file.txt")
// define the string/text to be saved
let text = "Hello World !!!"
// writing to disk
// Note: if you set atomically to true it will overwrite the file if it exists without a warning
try text.write(to: fileURL, atomically: false, encoding: .utf8)
print("saving was successful")
// any posterior code goes here
// reading from disk
let savedText = try String(contentsOf: fileURL)
print("savedText:", savedText) // "Hello World !!!\n"
}
} catch {
print("error:", error)
}
答案 3 :(得分:50)
新的更简单和推荐的方法: Apple建议使用URL进行文件处理,上述解决方案似乎已被弃用(请参阅下面的评论)。 以下是使用URL进行读写的新简单方法(不要忘记处理可能的URL错误):
Swift 4.0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)
// If the directory was found, we write a file to it and read it back
if let fileURL = dir?.appendingPathComponent(fileName).appendingPathExtension("txt") {
// Write to the file named Test
let outString = "Write this text to the file"
do {
try outString.write(to: fileURL, atomically: true, encoding: .utf8)
} catch {
print("Failed writing to URL: \(fileURL), Error: " + error.localizedDescription)
}
// Then reading it back from the file
var inString = ""
do {
inString = try String(contentsOf: fileURL)
} catch {
print("Failed reading from URL: \(fileURL), Error: " + error.localizedDescription)
}
print("Read from the file: \(inString)")
}
答案 4 :(得分:28)
Xcode 8,Swift 3方式从应用程序包中读取文件:
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程序
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()
你几乎总是想要一系列的行:
let r:[String] = "yourFile.txt"
.contentsOrBlank()
.characters
.split(separator: "\n", omittingEmptySubsequences:ignore)
.map(String.init)
答案 5 :(得分:11)
我只想向您展示第一部分,即阅读。您可以阅读以下内容:
斯威夫特3:
let s = try String(contentsOfFile: Bundle.main.path(forResource: "myFile", ofType: "txt")!)
Swift 2:
let s = try! String(contentsOfFile: NSBundle.mainBundle().pathForResource("myFile", ofType: "txt")!)
答案 6 :(得分:4)
在Swift> 4.0中读取文件的最简单方法
taskkill /FI "WINDOWTITLE eq Hello*"
答案 7 :(得分:3)
您可能会发现此工具不仅可以读取Swift中的文件,还可以解析您的输入:https://github.com/shoumikhin/StreamScanner
只需指定文件路径和数据分隔符,如下所示:
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。
答案 8 :(得分:3)
亚当当前接受的答案对我来说有些错误,但这是我如何重写他的答案并让我为我工作。
let file = "file.txt"
let dirs: [String]? = NSSearchPathForDirectoriesInDomains(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomainMask.AllDomainsMask, true) as? [String]
if (dirs != nil) {
let directories:[String] = dirs!
let dirs = directories[0]; //documents directory
let path = dirs.stringByAppendingPathComponent(file);
let text = "some text"
//writing
text.writeToFile(path, atomically: false, encoding: NSUTF8StringEncoding, error: nil);
//reading
var error:NSError?
//reading
let text2 = String(contentsOfFile: path, encoding:NSUTF8StringEncoding, error: &error)
if let theError = error {
print("\(theError.localizedDescription)")
}
}
答案 9 :(得分:2)
为了避免混淆和增加简易性,我创建了两个函数来读取和写入文档目录中的文件。以下是功能:
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
}
以下是它们的使用示例:
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.'
希望这有帮助!
Xcode版本:6.3.2
答案 10 :(得分:2)
我不得不像这样重新编码:
let path = NSBundle.mainBundle().pathForResource("Output_5", ofType: "xml")
let text = try? NSString(contentsOfFile: path! as String, encoding: NSUTF8StringEncoding)
print(text)
答案 11 :(得分:2)
在函数示例中,(read | write)DocumentsFromFile(...)具有一些函数包装器当然似乎有意义,因为OSx和iOS中的所有内容似乎需要实例化三个或四个主要类以及一堆属性,已配置,链接,实例化和设置,只是为182个国家/地区的文件写“嗨”。
但是,这些示例不够完整,无法在实际程序中使用。 write函数不会报告创建或写入文件的任何错误。在阅读中,我不认为返回错误,该文件不存在作为应该包含已读取数据的字符串。你会想知道它失败了,为什么,通过一些通知机制,就像一个例外。然后,您可以编写一些输出问题所在的代码,并允许用户更正它,或者“正确”地破坏程序。
您不希望只返回一个字符串,其中包含“错误文件不存在”。然后,您必须每次从调用函数中查找字符串中的错误并在那里处理它。您也可能无法确定错误字符串是否实际从实际文件中读取,或者是否是从您的代码生成的。
你甚至无法在swift 2.2和Xcode 7.3中调用这样的读取,因为NSString(contentsOfFile ...)会抛出异常。如果您没有任何代码来捕获它并对其执行某些操作,例如将其打印到stdout,或者更好,错误弹出窗口或stderr,那么这是一个编译时错误。我听说Apple正在逐渐尝试捕获和异常,但这将是一个漫长的举动,没有这个就不可能编写代码。我不知道& error参数来自哪里,可能是旧版本,但NSString.writeTo [File | URL]目前没有NSError参数。它们在NSString.h中定义如下:
public func writeToURL(url: NSURL, atomically useAuxiliaryFile: Bool, encoding enc: UInt) throws
public func writeToFile(path: String, atomically useAuxiliaryFile: Bool, encoding enc: UInt) throws
public convenience init(contentsOfURL url: NSURL, encoding enc: UInt) throws
public convenience init(contentsOfFile path: String, encoding enc: UInt) throws
此外,文件不存在只是您的程序可能读取文件的许多潜在问题之一,例如权限问题,文件大小或许多其他您甚至不想尝试编码的问题每个人的处理程序。如果出现问题,最好只是假设它是正确的并捕捉和打印或处理异常,此时,你还没有真正的选择。
以下是我的重写:
func writeToDocumentsFile(fileName:String,value:String) {
let documentsPath = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0] as NSString!
let path = documentsPath.stringByAppendingPathComponent(fileName)
do {
try value.writeToFile(path, atomically: true, encoding: NSUTF8StringEncoding)
} catch let error as NSError {
print("ERROR : writing to file \(path) : \(error.localizedDescription)")
}
}
func readFromDocumentsFile(fileName:String) -> String {
let documentsPath = NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0] as NSString
let path = documentsPath.stringByAppendingPathComponent(fileName)
var readText : String = ""
do {
try readText = NSString(contentsOfFile: path, encoding: NSUTF8StringEncoding) as String
}
catch let error as NSError {
print("ERROR : reading from file \(fileName) : \(error.localizedDescription)")
}
return readText
}
答案 12 :(得分:2)
我的txt文件以这种方式工作:
let myFileURL = NSBundle.mainBundle().URLForResource("listacomuni", withExtension: "txt")!
let myText = try! String(contentsOfURL: myFileURL, encoding: NSISOLatin1StringEncoding)
print(String(myText))
答案 13 :(得分:2)
最新的swift3代码
您可以使用下面的代码从文本文件中读取数据
这是我的文本文件
{
"NumberOfSlices": "8",
"NrScenes": "5",
"Scenes": [{
"dataType": "label1",
"image":"http://is3.mzstatic.com/image/thumb/Purple19/v4/6e/81/31/6e8131cf-2092-3cd3-534c-28e129897ca9/mzl.syvaewyp.png/53x53bb-85.png",
"value": "Hello",
"color": "(UIColor.red)"
}, {
"dataType": "label2",
"image":"http://is1.mzstatic.com/image/thumb/Purple71/v4/6c/4c/c1/6c4cc1bc-8f94-7b13-f3aa-84c41443caf3/mzl.hcqvmrix.png/53x53bb-85.png",
"value": "Hi There",
"color": "(UIColor.blue)"
}, {
"dataType": "label3",
"image":"http://is1.mzstatic.com/image/thumb/Purple71/v4/6c/4c/c1/6c4cc1bc-8f94-7b13-f3aa-84c41443caf3/mzl.hcqvmrix.png/53x53bb-85.png",
"value": "hi how r u ",
"color": "(UIColor.green)"
}, {
"dataType": "label4",
"image":"http://is1.mzstatic.com/image/thumb/Purple71/v4/6c/4c/c1/6c4cc1bc-8f94-7b13-f3aa-84c41443caf3/mzl.hcqvmrix.png/53x53bb-85.png",
"value": "what are u doing ",
"color": "(UIColor.purple)"
}, {
"dataType": "label5",
"image":"http://is1.mzstatic.com/image/thumb/Purple71/v4/6c/4c/c1/6c4cc1bc-8f94-7b13-f3aa-84c41443caf3/mzl.hcqvmrix.png/53x53bb-85.png",
"value": "how many times ",
"color": "(UIColor.white)"
}, {
"dataType": "label6",
"image":"http://is1.mzstatic.com/image/thumb/Purple71/v4/5a/f3/06/5af306b0-7cac-1808-f440-bab7a0d18ec0/mzl.towjvmpm.png/53x53bb-85.png",
"value": "hi how r u ",
"color": "(UIColor.blue)"
}, {
"dataType": "label7",
"image":"http://is5.mzstatic.com/image/thumb/Purple71/v4/a8/dc/eb/a8dceb29-6daf-ca0f-d037-df9f34cdc476/mzl.ukhhsxik.png/53x53bb-85.png",
"value": "hi how r u ",
"color": "(UIColor.gry)"
}, {
"dataType": "label8",
"image":"http://is2.mzstatic.com/image/thumb/Purple71/v4/15/23/e0/1523e03c-fff2-291e-80a7-73f35d45c7e5/mzl.zejcvahm.png/53x53bb-85.png",
"value": "hi how r u ",
"color": "(UIColor.brown)"
}]
}
您可以使用此代码从swift3
中的文本json文件中获取数据 let filePath = Bundle.main.path(forResource: "nameoftheyourjsonTextfile", ofType: "json")
let contentData = FileManager.default.contents(atPath: filePath!)
let content = NSString(data: contentData!, encoding: String.Encoding.utf8.rawValue) as? String
print(content)
let json = try! JSONSerialization.jsonObject(with: contentData!) as! NSDictionary
print(json)
let app = json.object(forKey: "Scenes") as! NSArray!
let _ : NSDictionary
for dict in app! {
let colorNam = (dict as AnyObject).object(forKey: "color") as! String
print("colors are \(colorNam)")
// let colour = UIColor(hexString: colorNam) {
// colorsArray.append(colour.cgColor)
// colorsArray.append(colorNam as! UIColor)
let value = (dict as AnyObject).object(forKey: "value") as! String
print("the values are \(value)")
valuesArray.append(value)
let images = (dict as AnyObject).object(forKey: "image") as! String
let url = URL(string: images as String)
let data = try? Data(contentsOf: url!)
print(data)
let image1 = UIImage(data: data!)! as UIImage
imagesArray.append(image1)
print(image1)
}
答案 14 :(得分:2)
这适用于Linux上的Swift 3.1.1:
import Foundation
let s = try! String(contentsOfFile: "yo", encoding: .utf8)
答案 15 :(得分:1)
在ViewDidLoad中写入
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 []
}
答案 16 :(得分:1)
早期的解决方案可以回答问题,但是在我的情况下,在写入时删除文件的旧内容是一个问题。
因此,我创建了一段代码,用于写入文件目录中的文件,而不删除先前的内容。您可能需要更好的错误处理,但是我相信这是一个很好的起点。迅捷4。 用法:
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)
}
Helper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
}
}
答案 17 :(得分:0)
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
}
答案 18 :(得分:0)
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")
}
将文件写入文件
NSKeyedArchiver.archiveRootObject(finalDataDict, toFile:(jsonFilePath?.absoluteString)!)
答案 19 :(得分:0)
最好的示例是创建带有扩展名Logfile
的本地.txt
可以显示并在"Files App"
中显示,并以当前日期和时间作为文件名
只需添加此代码
info.plist中的
启用这两个功能
UIFileSharingEnabled
LSSupportsOpeningDocumentsInPlace
以及下面的此功能
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 */}
}
}
答案 20 :(得分:0)
建议异步读写文件!在纯Swift中非常容易做到,
这是协议:
type="button"
如您所见,它允许您同步或异步读取和写入文件。
这是我在Swift 5中的实现:
protocol FileRepository {
func read(from path: String) throws -> String
func readAsync(from path: String, completion: @escaping (Result<String, Error>) -> Void)
func write(_ string: String, to path: String) throws
func writeAsync(_ string: String, to path: String, completion: @escaping (Result<Void, Error>) -> Void)
}