How to download file in swift?

Example downloader class without 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()    }}

This is how to use it in your own code:

class Foo {    func bar() {        if var URL = NSURL(string: "http://www.mywebsite.com/myfile.pdf") {            Downloader.load(URL)        }    }}

Swift 3 Version

Also note to download large files on disk instead instead in memory. see `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()    }}

Swift 4 and Swift 5 Version if Anyone still needs this

import Foundationclass FileDownloader {    static func loadFileSync(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)        {            print("File already exists [\(destinationUrl.path)]")            completion(destinationUrl.path, nil)        }        else if let dataFromURL = NSData(contentsOf: url)        {            if dataFromURL.write(to: destinationUrl, atomically: true)            {                print("file saved [\(destinationUrl.path)]")                completion(destinationUrl.path, nil)            }            else            {                print("error saving file")                let error = NSError(domain:"Error saving file", code:1001, userInfo:nil)                completion(destinationUrl.path, error)            }        }        else        {            let error = NSError(domain:"Error downloading file", code:1002, userInfo:nil)            completion(destinationUrl.path, error)        }    }    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)        {            print("File already exists [\(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()        }    }}

Here is how to call this method :-

let url = URL(string: "http://www.filedownloader.com/mydemofile.pdf")FileDownloader.loadFileAsync(url: url!) { (path, error) in    print("PDF File downloaded to : \(path!)")}

Here's an example that shows how to do sync & async.

import Foundationclass 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()        }    }}

Here's how to use it in your code:

let url = NSURL(string: "http://www.mywebsite.com/myfile.pdf") HttpDownloader.loadFileAsync(url, completion:{(path:String, error:NSError!) in                println("pdf downloaded to: \(path)")            })