我需要从一个文本文件读取和写入数据,但我还没有弄清楚怎么做。
我在Swift的iBook中找到了这个示例代码,但我仍然不知道如何写入或读取数据。
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."
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
}
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 []
}
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)!)