Alamofire.download() method: Where is the file and did it save successfully?

Question

The example for using Alamofire.download() works just fine, but there isn't any detail in how to access the resulting downloaded file. I can figure out where the file is and what it was named based on the destination I set and the original file request I made, but I would assume that there is a value I should be able to access to get the full final download path and file name in the response.

How do I access the name of the file and how do I know if it saved successfully? I can see delegate methods in the actual Alamofire code that appear to handle the delegate completion calls for the downloading process, but how do I / can I access the file details in the .response block?

I was about to ask the same question as I have the same problem right now! — dschlossfr, Oct 16 '14 at 17:10

score 27 · Answer 1 · edited Jan 31 '21 at 08:42

27

Swift 2.1 and a little simpler:

var localPath: NSURL?
Alamofire.download(.GET,
    "http://jplayer.org/video/m4v/Big_Buck_Bunny_Trailer.m4v",
    destination: { (temporaryURL, response) in
    let directoryURL = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)[0]
    let pathComponent = response.suggestedFilename
            
    localPath = directoryURL.URLByAppendingPathComponent(pathComponent!)
        return localPath!
    })
    .response { (request, response, _, error) in
        print(response)
        print("Downloaded file to \(localPath!)")
    }
)

Still hard to understand why they are using closures to set the destination path...

edited Jan 31 '21 at 08:42

Community

1
1

answered Nov 20 '15 at 21:56

Sam

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If the destination file already exists, the rename/move will fail, so handling that case in the closure is handy, if you want to make use of the suggested filename. – penfold Jan 04 '16 at 06:04
@penfold true this saves me a lot of effort by writing the logic to replace the existing file with new file and restoring from temp file if the download fails. Im really happy that its a closure. – spaceMonkey Jul 11 '16 at 07:08

score 13 · Accepted Answer · answered Oct 16 '14 at 21:04

The example on the Alamofire readme file actually has the file path in it, so I grab it with a separate variable to use elsewhere in my code. It is not very elegant and I am hoping there is a way to get that info in the response, but for now, this is getting the job done:

var fileName: String?
var finalPath: NSURL?

Alamofire.download(.GET, urlToCall, { (temporaryURL, response) in

    if let directoryURL = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)[0] as? NSURL {    

        fileName = response.suggestedFilename!
        finalPath = directoryURL.URLByAppendingPathComponent(fileName!)
        return finalPath!
    }

    return temporaryURL
})
    .response { (request, response, data, error) in

        if error != nil {
            println("REQUEST: \(request)")
            println("RESPONSE: \(response)")
        } 

        if finalPath != nil {
            doSomethingWithTheFile(finalPath!, fileName: fileName!)
        }
 }

you can't access to finalPath or fileName variable from there — Gabriel Goncalves, Mar 27 '15 at 15:42
If you want to access finalPath or fileName in the closure, you need to change the download call to "Alamofire.download(.GET, urlToCall, { [weak self] (temporaryURL, response) in" Then you can reference self.fileName and self.finalPath without causing a retain cycle. Also, you need to put this code in a class that's instantiated in a place where it won't go out of scope before the request completes. A simpler approach is to add a completion handling closure to the function where this code is, and pass finalPath to that completion handler. — Carl Smith, Jul 07 '16 at 20:26

score 3 · Answer 3 · answered Jun 21 '15 at 05:49

I spent about 8 hours looking for an answer to this one. The solution below works for me, and basically I chain to the download method to display the image. In the example below, I'm downloading the profile image of a user knowing his Facebook ID:

    let imageURL = "http://graph.facebook.com/\(FBId!)/picture?type=large"

    let destination: (NSURL, NSHTTPURLResponse) -> (NSURL) = {
        (temporaryURL, response) in

        if let directoryURL = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)[0] as? NSURL {
            var localImageURL = directoryURL.URLByAppendingPathComponent("\(self.FBId!).\(response.suggestedFilename!)")
            return localImageURL
        }
        return temporaryURL
    }

    Alamofire.download(.GET, imageURL, destination).response(){
        (_, _, data, _) in
            if let directoryURL = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)[0] as? NSURL {
                var error: NSError?
                let urls = NSFileManager.defaultManager().contentsOfDirectoryAtURL(directoryURL, includingPropertiesForKeys: nil, options: nil, error: &error)

                if error == nil {
                    let downloadedPhotoURLs = urls as! [NSURL]
                    let imagePath = downloadedPhotoURLs[0] // assuming it's the first file
                    let data = NSData(contentsOfURL: imagePath)
                    self.viewProfileImage?.image = UIImage(data: data!)
                }
            }
    }

score 2 · Answer 4 · answered May 26 '16 at 08:03

Here is complete method to download file in different destination with progress

//MARK: Download methods

func downloadFile(reqType : RequestType,  urlParam: String,completionHandler: (Double?, NSError?) -> Void) {

    let documentsPath = NSURL(fileURLWithPath: NSSearchPathForDirectoriesInDomains(.DocumentDirectory, .UserDomainMask, true)[0])
    var downloadPath = documentsPath.URLByAppendingPathComponent("downloads")
    var isDirectory: ObjCBool = false
    if NSFileManager.defaultManager().fileExistsAtPath(downloadPath.path!, isDirectory: &isDirectory) {
        if(!isDirectory){
            do {
                try NSFileManager.defaultManager().createDirectoryAtPath(downloadPath.path!, withIntermediateDirectories: true, attributes: nil)
            }catch  {
                NSLog("Unable to create directory ")
            }
        }
    }else{
        do {
            try NSFileManager.defaultManager().createDirectoryAtPath(downloadPath.path!, withIntermediateDirectories: true, attributes: nil)
        }catch  {
            NSLog("Unable to create directory ")
        }

    }


    //get the url from GTM
    let urlString = self.getRequestedUrlFromIdentifier(reqType, param: urlParam)
    let destination = Alamofire.Request.suggestedDownloadDestination(directory: .DocumentDirectory, domain: .UserDomainMask)
    Alamofire.download(.GET, urlString, destination: { (temporaryURL, response) in

        let pathComponent = response.suggestedFilename
        downloadPath = downloadPath.URLByAppendingPathComponent(pathComponent!)
        if NSFileManager.defaultManager().fileExistsAtPath(downloadPath.path!) {
            do{
             try NSFileManager.defaultManager().removeItemAtPath(downloadPath.path!)
            }catch {

            }
        }
        return downloadPath
    })            .progress { bytesRead, totalBytesRead, totalBytesExpectedToRead in
            print(totalBytesRead)

            // This closure is NOT called on the main queue for performance
            // reasons. To update your ui, dispatch to the main queue.
            dispatch_async(dispatch_get_main_queue()) {
                print("Total bytes read on main queue: \(totalBytesRead)")
            }
        }
        .response { request, response, _, error in
            print(response)
            let originalPath = destination(NSURL(string: "")!, response!)
            if let error = error {
                completionHandler(500000.1 , nil)
                print("Failed with error: \(error)")
            } else {
                completionHandler(500000.0 , nil)
                print("Downloaded file successfully \(downloadPath)")
            }
    }

}

score 2 · Answer 5 · answered Aug 31 '16 at 14:10

This answer from an Alamofire member seems to be the best answer:

let destination = Alamofire.Request.suggestedDownloadDestination(
    directory: .CachesDirectory,
    domain: .UserDomainMask
)

Alamofire.download(.GET, "http://www.adobe.com/devnet/acrobat/pdfs/pdf_open_parameters.pdf", destination: destination)
    .progress { bytesRead, totalBytesRead, totalBytesExpectedToRead in
        print(totalBytesRead)
    }
    .response { request, response, _, error in
        print(response)
        print("fileURL: \(destination(NSURL(string: "")!, response))")
}

Alamofire.download() method: Where is the file and did it save successfully?

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