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."
斯威夫特3。X - 5.x
最好的例子是创建一个扩展名为.txt的本地日志文件
可以在“文件应用程序”中显示当前日期和时间作为文件名
只需在信息中添加此代码。请启用这两个功能
UIFileSharingEnabled
LSSupportsOpeningDocumentsInPlace
和下面的函数
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 */}
}
}
[1]: https://i.stack.imgur.com/4eg12.png
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, Swift 3从应用程序包中读取文件的方法:
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
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()
你几乎总是想要一个行数组:
let r:[String] = "yourFile.txt"
.contentsOrBlank()
.characters
.split(separator: "\n", omittingEmptySubsequences:ignore)
.map(String.init)
斯威夫特3。X - 5.x
最好的例子是创建一个扩展名为.txt的本地日志文件
可以在“文件应用程序”中显示当前日期和时间作为文件名
只需在信息中添加此代码。请启用这两个功能
UIFileSharingEnabled
LSSupportsOpeningDocumentsInPlace
和下面的函数
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 */}
}
}
[1]: https://i.stack.imgur.com/4eg12.png