¿Cómo descargar un archivo en swift?
Acabo de empezar a aprender Apple swift programación para iOS procedente de Android. Básicamente ahora puedo leer y manipular el código swift y también aprendí algunas clases comunes que se usan en la programación swift de iOS, pero todavía tengo cierta confusión con la sintaxis y todo.
Estoy tratando de descargar el archivo. Como, vamos a decir que viene de esta URL
var url = "http://www.mywebsite.com/myfile.pdf"
En un clic de botón. Tal vez con el progreso visual también
Al buscar aquí en stackoverflow, me topé con Alamofire. Me podría intentarlo, pero no estoy seguro de si esta es la mejor manera de hacerlo.
Por lo tanto, me gustaría preguntar cómo y cuáles son mis opciones (iOS7 e iOS8) para lograr mi objetivo. Además, pros y contras sería increíble!
10 answers
Ejemplo de clase de downloader sin Alamofire:
class Downloader {
class func load(URL: NSURL) {
let sessionConfig = NSURLSessionConfiguration.defaultSessionConfiguration()
let session = NSURLSession(configuration: sessionConfig, delegate: nil, delegateQueue: nil)
let request = NSMutableURLRequest(URL: URL)
request.HTTPMethod = "GET"
let task = session.dataTaskWithRequest(request, completionHandler: { (data: NSData!, response: NSURLResponse!, error: NSError!) -> Void in
if (error == nil) {
// Success
let statusCode = (response as NSHTTPURLResponse).statusCode
println("Success: \(statusCode)")
// This is your file-variable:
// data
}
else {
// Failure
println("Failure: %@", error.localizedDescription);
}
})
task.resume()
}
}
Esta es la forma de usarlo en su propio código:
class Foo {
func bar() {
if var URL = NSURL(string: "http://www.mywebsite.com/myfile.pdf") {
Downloader.load(URL)
}
}
}
Versión Swift 3
También tenga en cuenta que debe descargar archivos grandes en el disco en lugar de en la memoria. ver ' downloadTask:
class Downloader {
class func load(url: URL, to localUrl: URL, completion: @escaping () -> ()) {
let sessionConfig = URLSessionConfiguration.default
let session = URLSession(configuration: sessionConfig)
let request = try! URLRequest(url: url, method: .get)
let task = session.downloadTask(with: request) { (tempLocalUrl, response, error) in
if let tempLocalUrl = tempLocalUrl, error == nil {
// Success
if let statusCode = (response as? HTTPURLResponse)?.statusCode {
print("Success: \(statusCode)")
}
do {
try FileManager.default.copyItem(at: tempLocalUrl, to: localUrl)
completion()
} catch (let writeError) {
print("error writing file \(localUrl) : \(writeError)")
}
} else {
print("Failure: %@", error?.localizedDescription);
}
}
task.resume()
}
}
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2016-09-16 09:20:46
Aquí hay un ejemplo que muestra cómo sincronizar y asincronar.
import Foundation
class HttpDownloader {
class func loadFileSync(url: NSURL, completion:(path:String, error:NSError!) -> Void) {
let documentsUrl = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask).first as! NSURL
let destinationUrl = documentsUrl.URLByAppendingPathComponent(url.lastPathComponent!)
if NSFileManager().fileExistsAtPath(destinationUrl.path!) {
println("file already exists [\(destinationUrl.path!)]")
completion(path: destinationUrl.path!, error:nil)
} else if let dataFromURL = NSData(contentsOfURL: url){
if dataFromURL.writeToURL(destinationUrl, atomically: true) {
println("file saved [\(destinationUrl.path!)]")
completion(path: destinationUrl.path!, error:nil)
} else {
println("error saving file")
let error = NSError(domain:"Error saving file", code:1001, userInfo:nil)
completion(path: destinationUrl.path!, error:error)
}
} else {
let error = NSError(domain:"Error downloading file", code:1002, userInfo:nil)
completion(path: destinationUrl.path!, error:error)
}
}
class func loadFileAsync(url: NSURL, completion:(path:String, error:NSError!) -> Void) {
let documentsUrl = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask).first as! NSURL
let destinationUrl = documentsUrl.URLByAppendingPathComponent(url.lastPathComponent!)
if NSFileManager().fileExistsAtPath(destinationUrl.path!) {
println("file already exists [\(destinationUrl.path!)]")
completion(path: destinationUrl.path!, error:nil)
} else {
let sessionConfig = NSURLSessionConfiguration.defaultSessionConfiguration()
let session = NSURLSession(configuration: sessionConfig, delegate: nil, delegateQueue: nil)
let request = NSMutableURLRequest(URL: url)
request.HTTPMethod = "GET"
let task = session.dataTaskWithRequest(request, completionHandler: { (data: NSData!, response: NSURLResponse!, error: NSError!) -> Void in
if (error == nil) {
if let response = response as? NSHTTPURLResponse {
println("response=\(response)")
if response.statusCode == 200 {
if data.writeToURL(destinationUrl, atomically: true) {
println("file saved [\(destinationUrl.path!)]")
completion(path: destinationUrl.path!, error:error)
} else {
println("error saving file")
let error = NSError(domain:"Error saving file", code:1001, userInfo:nil)
completion(path: destinationUrl.path!, error:error)
}
}
}
}
else {
println("Failure: \(error.localizedDescription)");
completion(path: destinationUrl.path!, error:error)
}
})
task.resume()
}
}
}
Aquí está cómo usarlo en su código:
let url = NSURL(string: "http://www.mywebsite.com/myfile.pdf")
HttpDownloader.loadFileAsync(url, completion:{(path:String, error:NSError!) in
println("pdf downloaded to: \(path)")
})
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2015-05-07 16:33:05
Las soluciones de Devran y djunod funcionan siempre que su aplicación esté en primer plano. Si cambia a otra aplicación durante la descarga, fallará. Mis tamaños de archivo son de alrededor de 10 MB y tarda algún tiempo en descargarse. Así que necesito que mi función de descarga funcione incluso cuando la aplicación pasa a segundo plano.
Tenga en cuenta que activé "Modos de fondo / Búsqueda de fondo" en "Capacidades".
Dado que el controlador de terminación no fue soportado, la solución no es encapsulado. Disculpame por eso.
Swift Swift 2.3 {
import Foundation
class Downloader : NSObject, NSURLSessionDownloadDelegate
{
var url : NSURL?
// will be used to do whatever is needed once download is complete
var yourOwnObject : NSObject?
init(yourOwnObject : NSObject)
{
self.yourOwnObject = yourOwnObject
}
//is called once the download is complete
func URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask, didFinishDownloadingToURL location: NSURL)
{
//copy downloaded data to your documents directory with same names as source file
let documentsUrl = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask).first
let destinationUrl = documentsUrl!.URLByAppendingPathComponent(url!.lastPathComponent!)
let dataFromURL = NSData(contentsOfURL: location)
dataFromURL?.writeToURL(destinationUrl, atomically: true)
//now it is time to do what is needed to be done after the download
yourOwnObject!.callWhatIsNeeded()
}
//this is to track progress
func URLSession(session: NSURLSession, downloadTask: NSURLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64)
{
}
// if there is an error during download this will be called
func URLSession(session: NSURLSession, task: NSURLSessionTask, didCompleteWithError error: NSError?)
{
if(error != nil)
{
//handle the error
print("Download completed with error: \(error!.localizedDescription)");
}
}
//method to be called to download
func download(url: NSURL)
{
self.url = url
//download identifier can be customized. I used the "ulr.absoluteString"
let sessionConfig = NSURLSessionConfiguration.backgroundSessionConfigurationWithIdentifier(url.absoluteString)
let session = NSURLSession(configuration: sessionConfig, delegate: self, delegateQueue: nil)
let task = session.downloadTaskWithURL(url)
task.resume()
}
}
Y aquí está cómo llamar en Swift Swift 2.3 {
let url = NSURL(string: "http://company.com/file.txt")
Downloader(yourOwnObject).download(url!)
Swift Swift 3 {
class Downloader : NSObject, URLSessionDownloadDelegate {
var url : URL?
// will be used to do whatever is needed once download is complete
var yourOwnObject : NSObject?
init(_ yourOwnObject : NSObject)
{
self.yourOwnObject = yourOwnObject
}
//is called once the download is complete
func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL)
{
//copy downloaded data to your documents directory with same names as source file
let documentsUrl = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first
let destinationUrl = documentsUrl!.appendingPathComponent(url!.lastPathComponent)
let dataFromURL = NSData(contentsOf: location)
dataFromURL?.write(to: destinationUrl, atomically: true)
//now it is time to do what is needed to be done after the download
yourOwnObject!.callWhatIsNeeded()
}
//this is to track progress
private func URLSession(session: URLSession, downloadTask: URLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64)
{
}
// if there is an error during download this will be called
func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?)
{
if(error != nil)
{
//handle the error
print("Download completed with error: \(error!.localizedDescription)");
}
}
//method to be called to download
func download(url: URL)
{
self.url = url
//download identifier can be customized. I used the "ulr.absoluteString"
let sessionConfig = URLSessionConfiguration.background(withIdentifier: url.absoluteString)
let session = Foundation.URLSession(configuration: sessionConfig, delegate: self, delegateQueue: nil)
let task = session.downloadTask(with: url)
task.resume()
}}
Y aquí es cómo llamar en Swift Swift 3 {
let url = URL(string: "http://company.com/file.txt")
Downloader(yourOwnObject).download(url!)
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2017-03-29 13:34:20
Si necesita descargar solo el archivo de texto en String
puede usar esta manera simple, Swift 3:
let list = try? String(contentsOf: URL(string: "https://example.com/file.txt")!)
En caso de que desee un manejo no opcional de resultados o errores:
do {
let list = try String(contentsOf: URL(string: "https://example.com/file.txt")!)
}
catch {
// Handle error here
}
Debe saber que las operaciones de red pueden tomar algún tiempo, para evitar que se ejecute en el subproceso principal y bloquee su interfaz de usuario, es posible que desee ejecutar el código de forma asíncrona, por ejemplo:
DispatchQueue.global().async {
let list = try? String(contentsOf: URL(string: "https://example.com/file.txt")!)
}
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2016-08-03 09:49:17
Swift 3
Desea descargar el archivo mordida por mordida y mostrar en progreso vista así que quieres probar este código
import UIKit
class ViewController: UIViewController,URLSessionDownloadDelegate,UIDocumentInteractionControllerDelegate {
@IBOutlet weak var img: UIImageView!
@IBOutlet weak var btndown: UIButton!
var urlLink: URL!
var defaultSession: URLSession!
var downloadTask: URLSessionDownloadTask!
//var backgroundSession: URLSession!
@IBOutlet weak var progress: UIProgressView!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
let backgroundSessionConfiguration = URLSessionConfiguration.background(withIdentifier: "backgroundSession")
defaultSession = Foundation.URLSession(configuration: backgroundSessionConfiguration, delegate: self, delegateQueue: OperationQueue.main)
progress.setProgress(0.0, animated: false)
}
func startDownloading () {
let url = URL(string: "http://publications.gbdirect.co.uk/c_book/thecbook.pdf")!
downloadTask = defaultSession.downloadTask(with: url)
downloadTask.resume()
}
@IBAction func btndown(_ sender: UIButton) {
startDownloading()
}
func showFileWithPath(path: String){
let isFileFound:Bool? = FileManager.default.fileExists(atPath: path)
if isFileFound == true{
let viewer = UIDocumentInteractionController(url: URL(fileURLWithPath: path))
viewer.delegate = self
viewer.presentPreview(animated: true)
}
}
// MARK:- URLSessionDownloadDelegate
func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) {
print(downloadTask)
print("File download succesfully")
let path = NSSearchPathForDirectoriesInDomains(FileManager.SearchPathDirectory.documentDirectory, FileManager.SearchPathDomainMask.userDomainMask, true)
let documentDirectoryPath:String = path[0]
let fileManager = FileManager()
let destinationURLForFile = URL(fileURLWithPath: documentDirectoryPath.appendingFormat("/file.pdf"))
if fileManager.fileExists(atPath: destinationURLForFile.path){
showFileWithPath(path: destinationURLForFile.path)
print(destinationURLForFile.path)
}
else{
do {
try fileManager.moveItem(at: location, to: destinationURLForFile)
// show file
showFileWithPath(path: destinationURLForFile.path)
}catch{
print("An error occurred while moving file to destination url")
}
}
}
func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64) {
progress.setProgress(Float(totalBytesWritten)/Float(totalBytesExpectedToWrite), animated: true)
}
func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?) {
downloadTask = nil
progress.setProgress(0.0, animated: true)
if (error != nil) {
print("didCompleteWithError \(error?.localizedDescription ?? "no value")")
}
else {
print("The task finished successfully")
}
}
func documentInteractionControllerViewControllerForPreview(_ controller: UIDocumentInteractionController) -> UIViewController
{
return self
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
}
El uso de este código que desea descargar archivo almacenar automáticamente en el Directorio de documentos en su aplicación
Este código funciona al 100%
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2017-05-18 08:38:25
Aquí está la versión Swift 4:
static func loadFileAsync(url: URL, completion: @escaping (String?, Error?) -> Void)
{
let documentsUrl = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
let destinationUrl = documentsUrl.appendingPathComponent(url.lastPathComponent)
if FileManager().fileExists(atPath: destinationUrl.path)
{
completion(destinationUrl.path, nil)
}
else
{
let session = URLSession(configuration: URLSessionConfiguration.default, delegate: nil, delegateQueue: nil)
var request = URLRequest(url: url)
request.httpMethod = "GET"
let task = session.dataTask(with: request, completionHandler:
{
data, response, error in
if error == nil
{
if let response = response as? HTTPURLResponse
{
if response.statusCode == 200
{
if let data = data
{
if let _ = try? data.write(to: destinationUrl, options: Data.WritingOptions.atomic)
{
completion(destinationUrl.path, error)
}
else
{
completion(destinationUrl.path, error)
}
}
else
{
completion(destinationUrl.path, error)
}
}
}
}
else
{
completion(destinationUrl.path, error)
}
})
task.resume()
}
}
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2018-03-11 09:08:17
Pruebe Este Código solo Swift 3.0 Primero Crea un Archivo de Objeto NS Copie este código en el archivo creado
import UIKit
class Downloader : NSObject, URLSessionDownloadDelegate {
var url : URL?
// will be used to do whatever is needed once download is complete
var obj1 : NSObject?
init(_ obj1 : NSObject)
{
self.obj1 = obj1
}
//is called once the download is complete
func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL)
{
//copy downloaded data to your documents directory with same names as source file
let documentsUrl = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first
let destinationUrl = documentsUrl!.appendingPathComponent(url!.lastPathComponent)
let dataFromURL = NSData(contentsOf: location)
dataFromURL?.write(to: destinationUrl, atomically: true)
//now it is time to do what is needed to be done after the download
//obj1!.callWhatIsNeeded()
}
//this is to track progress
private func URLSession(session: URLSession, downloadTask: URLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64)
{
}
// if there is an error during download this will be called
func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?)
{
if(error != nil)
{
//handle the error
print("Download completed with error: \(error!.localizedDescription)");
}
}
//method to be called to download
func download(url: URL)
{
self.url = url
//download identifier can be customized. I used the "ulr.absoluteString"
let sessionConfig = URLSessionConfiguration.background(withIdentifier: url.absoluteString)
let session = Foundation.URLSession(configuration: sessionConfig, delegate: self, delegateQueue: nil)
let task = session.downloadTask(with: url)
task.resume()
}}
Luego Copie el Código de abajo y coloque el código en el lugar de desea descargar el archivo
object = "http://www.mywebsite.com/myfile.pdf"
let url1 = URL(string: object!)
Downloader(url1! as NSObject).download(url: url1!)
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2017-05-18 08:30:00
Swift 3
class ViewController: UIViewController {
var urlLink: URL!
var defaultSession: URLSession!
var downloadTask: URLSessionDownloadTask!
}
// MARK: Button Pressed
@IBAction func btnDownloadPressed(_ sender: UIButton) {
let urlLink1 = URL.init(string: "https://github.com/VivekVithlani/QRCodeReader/archive/master.zip")
startDownloading(url: urlLink!)
}
@IBAction func btnResumePressed(_ sender: UIButton) {
downloadTask.resume()
}
@IBAction func btnStopPressed(_ sender: UIButton) {
downloadTask.cancel()
}
@IBAction func btnPausePressed(_ sender: UIButton) {
downloadTask.suspend()
}
func startDownloading (url:URL) {
let backgroundSessionConfiguration = URLSessionConfiguration.background(withIdentifier: "backgroundSession")
defaultSession = Foundation.URLSession(configuration: backgroundSessionConfiguration, delegate: self, delegateQueue: OperationQueue.main)
downloadProgress.setProgress(0.0, animated: false)
downloadTask = defaultSession.downloadTask(with: urlLink)
downloadTask.resume()
}
// MARK:- URLSessionDownloadDelegate
func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) {
print("File download succesfully")
}
func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64) {
downloadProgress.setProgress(Float(totalBytesWritten)/Float(totalBytesExpectedToWrite), animated: true)
}
func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?) {
downloadTask = nil
downloadProgress.setProgress(0.0, animated: true)
if (error != nil) {
print("didCompleteWithError \(error?.localizedDescription)")
}
else {
print("The task finished successfully")
}
}
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2017-01-11 07:00:25
Sí puede descargar Archivos fácilmente desde la Url remota Utilizando este código. Este Código funciona bien para Mí.
func DownlondFromUrl(){
// Create destination URL
let documentsUrl:URL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first as URL!
let destinationFileUrl = documentsUrl.appendingPathComponent("downloadedFile.jpg")
//Create URL to the source file you want to download
let fileURL = URL(string: "https://s3.amazonaws.com/learn-swift/IMG_0001.JPG")
let sessionConfig = URLSessionConfiguration.default
let session = URLSession(configuration: sessionConfig)
let request = URLRequest(url:fileURL!)
let task = session.downloadTask(with: request) { (tempLocalUrl, response, error) in
if let tempLocalUrl = tempLocalUrl, error == nil {
// Success
if let statusCode = (response as? HTTPURLResponse)?.statusCode {
print("Successfully downloaded. Status code: \(statusCode)")
}
do {
try FileManager.default.copyItem(at: tempLocalUrl, to: destinationFileUrl)
} catch (let writeError) {
print("Error creating a file \(destinationFileUrl) : \(writeError)")
}
} else {
print("Error took place while downloading a file. Error description: %@", error?.localizedDescription);
}
}
task.resume()
}
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2018-07-20 12:06:20
Use URLSessionDownloadTask
para descargar archivos en segundo plano para que puedan completarse incluso si la aplicación se termina.
Para más información ver:
Https://www.ralfebert.de/snippets/ios/urlsession-background-downloads /
También muestra cómo implementar el monitoreo de progreso para múltiples tareas que se ejecutan en paralelo:
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2017-05-18 08:16:26