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."
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 []
}
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 []
}
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)
对于读写，您应该使用一个可写的位置，例如文档目录。下面的代码展示了如何读写一个简单的字符串。你可以在操场上测试。
斯威夫特3。X - 5.x
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 */}
}
斯威夫特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 */}
}
快1.倍
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)
}
