iOS – Downloading a file from URL using an Alamofire

Himanshu Jindal

26 October 2021

There are various ways to download the files from a URL but the best way to download it using Alamofire because it provides us various sub functionalities like:

a) downloadProgress : For showing the fraction completed while downloading the files.

b) validation : Allows to check the errors while downloading the files.

c) responseData: Contains the response for download.

Here is the code for using the Almofire for downloading from the URL :

// MARK: - Load URL
    func downloadUsingAlamofire(url: URL, fileName: String) {
        
        let manager = Alamofire.SessionManager.default
        
        let destination: DownloadRequest.DownloadFileDestination = { _, _ in
            self.documentsURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]
            self.documentsURL.appendPathComponent(fileName)
            print(self.documentsURL)
            return (self.documentsURL, [.removePreviousFile])
        }
        
        manager.download(url, to: destination)
            
            .downloadProgress(queue: .main, closure: { (progress) in
                //progress closure
                print(progress.fractionCompleted)
            })
            .validate { request, response, temporaryURL, destinationURL in
                // Custom evaluation closure now includes file URLs (allows you to parse out error messages if necessary)
                GlobalData.sharedInstance.dismissLoader()
                return .success
            }
            
            .responseData { response in
                if let destinationUrl = response.destinationURL as? URL {
                    print(destinationUrl)
                    
                    if let statusCode = (response as? HTTPURLResponse)?.statusCode {
                        print("Success: \(statusCode)")
                        GlobalData.sharedInstance.dismissLoader()
                    }
                    
                    let AC = UIAlertController(title:GlobalData.sharedInstance.language(key: "success"), message:GlobalData.sharedInstance.language(key: "filesavemessage"), preferredStyle: .alert)
                    let okBtn = UIAlertAction(title: "view", style: .default, handler: {(_ action: UIAlertAction) -> Void in
                        self.documentPathUrl = response.destinationURL
                        //open file
                    })
                    let noBtn = UIAlertAction(title: GlobalData.sharedInstance.language(key: "cancel"), style: .destructive, handler: {(_ action: UIAlertAction) -> Void in
                    })
                    AC.addAction(okBtn)
                    AC.addAction(noBtn)
                    self.present(AC, animated: true, completion: { })
                } else {
                    GlobalData.sharedInstance.dismissLoader()
                }
            }
    }

// MARK: - Load URL

func downloadUsingAlamofire(url: URL, fileName: String) {

let manager = Alamofire.SessionManager.default

let destination: DownloadRequest.DownloadFileDestination = { _, _ in

self.documentsURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]

self.documentsURL.appendPathComponent(fileName)

print(self.documentsURL)

return (self.documentsURL, [.removePreviousFile])

}

manager.download(url, to: destination)

.downloadProgress(queue: .main, closure: { (progress) in

//progress closure

print(progress.fractionCompleted)

})

.validate { request, response, temporaryURL, destinationURL in

// Custom evaluation closure now includes file URLs (allows you to parse out error messages if necessary)

GlobalData.sharedInstance.dismissLoader()

return .success

}

.responseData { response in

if let destinationUrl = response.destinationURL as? URL {

print(destinationUrl)

if let statusCode = (response as? HTTPURLResponse)?.statusCode {

print("Success: \(statusCode)")

GlobalData.sharedInstance.dismissLoader()

}

let AC = UIAlertController(title:GlobalData.sharedInstance.language(key: "success"), message:GlobalData.sharedInstance.language(key: "filesavemessage"), preferredStyle: .alert)

let okBtn = UIAlertAction(title: "view", style: .default, handler: {(_ action: UIAlertAction) -> Void in

self.documentPathUrl = response.destinationURL

//open file

})

let noBtn = UIAlertAction(title: GlobalData.sharedInstance.language(key: "cancel"), style: .destructive, handler: {(_ action: UIAlertAction) -> Void in

})

AC.addAction(okBtn)

AC.addAction(noBtn)

self.present(AC, animated: true, completion: { })

} else {

GlobalData.sharedInstance.dismissLoader()

}

I hope from this, it will make you more comfortable using Alamofire functionality for downloading from the URL into your app. Thanks for tuning in once again!