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

问题

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?

回答1:

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...

回答2:

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!)
        }
 }

回答3:

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!)
                }
            }
    }

回答4:

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)")
            }
    }

}

回答5:

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))")
}

来源：https://stackoverflow.com/questions/26307170/alamofire-download-method-where-is-the-file-and-did-it-save-successfully

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