I have a video file on S3 that I am trying to save to disk. However, if the file already exists on disk, I want to overwrite it. I wrote this function to download the file but it never saves the file. I can see the progress % increasing. But, how do I access the resulting file and save it to disk?
var finalPath: NSURL?
Alamofire.download(.GET, s3Url) { temporaryURL, response in
let fileManager = NSFileManager.defaultManager()
if let directoryURL = fileManager.URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)[0] as? NSURL {
let pathComponent = response.suggestedFilename
finalPath = directoryURL.URLByAppendingPathComponent(pathComponent!)
println(finalPath)
//remove the file if it exists
if fileManager.fileExistsAtPath(finalPath!.absoluteString!) {
println("file exists on disk, removing..")
fileManager.removeItemAtPath(finalPath!.absoluteString!, error: nil)
}
return finalPath!
}
return temporaryURL
}
.validate()
.progress { bytesRead, totalBytesRead, totalBytesExpectedToRead in
let progress = (Double(totalBytesRead) / Double(totalBytesExpectedToRead)) * 100
println(String(format: "%.2f", progress))
}
.response { request, response, data, error in
println(request)
println(response)
if let mediaData = data {
println("saving file to disk")
mediaData.writeToURL(finalPath!, atomically: true)
}
}
Normally I would use the example provided in the docs, but It fails if the file already exists. ie:
let destination = Alamofire.Request.suggestedDownloadDestination(directory: .DocumentDirectory, domain: .UserDomainMask)
So, how can I download the file, overwrite it if it exists and record the path that the file is written to to my coreData database?
You need to delete the file first. Alamofire only tries to move the file from the temp location to the final location that you provide in the destination closure.
You can create an extension on Alamofire.DownloadRequest to provide options for how to download the file where you can use the option DownloadRequest.DownloadOptions.removePreviousFile.
for details on how to do that see my answer to this question.
Related
I'm currently trying to store some files on my iOS device. The contents of the file are encrypted, but I was wondering if I can append some kind of integrity check to the file as well, preferably using the FileAttributeKey.
I tried the following, which doesn't work
extension FileAttributeKey {
static let integrity = FileAttributeKey("NSFileIntegrity")
}
let docs = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!
let fileName = "test"
let filePath = docs.appendingPathComponent(fileName).path
defer {
try! FileManager.default.removeItem(atPath: filePath)
}
let data = Data("Hello world".utf8)
// This line fails too
// FileManager.default.createFile(atPath: filePath, contents: data, attributes: [.integrity: "SHA256"])
FileManager.default.createFile(atPath: filePath, contents: data, attributes: [:])
do {
try FileManager.default.setAttributes([.integrity: "SHA256"], ofItemAtPath: filePath)
} catch {
print(error)
}
print(try FileManager.default.attributesOfItem(atPath: filePath))
So the questions are:
Is there a way to create and append a custom FileAttributeKey to a file.
Is there a (better) way to add integrity checks to a file?
If you use authenticated encryption then you get integrity checks for free. Every time you decrypt, integrity will be checked for you and in case of errors the decryption will fail. Just use a mode like GCM or OCB and you are done.
I'm getting an Uncaught exemption within a http closure related to a dictionary stating there's an uncaught exemption. When I set a breakpoint exemptions, it points to a dictionary. The dictionary in question is declared in a struct as a static var and has multiple values already in it so how can this be happening? Here's the http request.
session.dataTask(with: request){ (data, response, error) in
if let data = data,
let tile = UIImage(data: data),
let documentsURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first{
let fileName = Date().timeIntervalSince1970
let filePath = documentsURL.appendingPathComponent(String(describing: fileName))
Maps.tileCachePath[url] = fileName //<- this is where the exception happens
//make sure there is no old file and if so delete it
if FileManager.default.fileExists(atPath: filePath.path){
do {
try FileManager.default.removeItem(at: filePath)
} catch{
print("error deleting old tile")
}
}
//now write the new file
FileManager.default.createFile(atPath: filePath.path, contents: data, attributes: nil)
print(filePath.path)
//return
result(tile, error)
} else {
result(nil, error)
}
}.resume()
It's a typo
Replace
Maps.tileCachePath[url] = fileName
with
Maps.tileCachePath[url] = filePath
Basically Date().timeIntervalSince1970 as a filename is a very bad idea. The number contains fractional seconds which are treated as a file extension.
Use a more reliable file name like a formatted date or at least remove the fractional seconds and add a real file extension.
Date().timeIntervalSince1970
is a double, you might need a string value there.
I’m trying to get String from txt file inside the zip file using native libcompression library. Actually I use the code from
https://github.com/mw99/DataCompression/blob/master/Sources/DataCompression.swift.
At first, I was doing:
let zip = try? Data(contentsOf: "/.../test.zip")
let tmp: Data? = zip?.unzip()
let txt: String? = String(data: tmp!, encoding: .utf8)
But how do I get the contents of zip file and how do I get data from certain txt file?
ZIP Foundation supports accessing individual entries in ZIP archives.
You have to initialize an archive by passing a file URL to the Archive initializer.
Afterwards you can access a specific entry via subscripting:
let fileManager = FileManager()
let currentWorkingPath = fileManager.currentDirectoryPath
var archiveURL = URL(fileURLWithPath: currentWorkingPath)
archiveURL.appendPathComponent("test.zip")
guard let archive = Archive(url: archiveURL, accessMode: .read) else {
return
}
guard let entry = archive["file.txt"] else {
return
}
var destinationURL = URL(fileURLWithPath: currentWorkingPath)
destinationURL.appendPathComponent("out.txt")
do {
try archive.extract(entry, to: destinationURL)
} catch {
print("Extracting entry from archive failed with error:\(error)")
}
You can also directly access the contents of entry by using the closure based API. This allows you to process the entry without writing it to the file system first:
try archive.extract(entry, consumer: { (data) in
print(data.count)
})
how can i keep a track or record of already downloaded files in alamofire swift 2.1 so that i don t have to download the same file again ? do we have any native method for that provided by alamofire or we have to do a check before downloading any file on our directory if we already have file with that name there ???? i'm confused on how to accomplish this with a proper approach
if anybody would clear my confusion about this then it'll be so helpful for me thanks
UPDATE:
let documentsURL = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)[0]
let fileUrl = documentsURL.URLByAppendingPathComponent(suggestedFileName)
print(fileUrl)
if !(NSFileManager.defaultManager().fileExistsAtPath(fileUrl.path!)){
self.suggestedFileName = (self.request?.response?.suggestedFilename)! // here how can i get the suggested download name before starting the download preocess ???
print("\(destination)")
request = Alamofire.download(.GET, "http://contentserver.adobe.com/store/books/GeographyofBliss_oneChapter.epub", destination: destination)
.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)")
self.progressView.setProgress(Float(totalBytesRead) / Float(totalBytesExpectedToRead), animated: true)
}
}
.response { _, _, _, error in
if let error = error {
print("Failed with error: \(error)")
} else {
print("Downloaded file successfully")
}
}
}else {
print("file already exists")
}
in the above update am trying to get the suggestedFileName which is generated by alamofire but there's one problem when am trying to get sugestedFileName like this : suggestedFileName = (request?.response?.suggestedFilename)! in viewdidload am getting a null exception off course because there's no suggestedFileName because download not yet started so my question is that how can i get the suggestedFileName from response before starting the download ??
According to the docs https://github.com/Alamofire/Alamofire#downloading, you can download to a file. If your file destinations names are predictable, you could simply check to see if the contents of the file exists. For example if your are downloading data:
if let data = NSData(contentsOfURL: yourDestinationURL) {
//Do your stuff here
}
else {
//Download it
}
If you want consistency between names I suggest you avoid the Alamofire suggested destination and do this instead:
let path = NSFileManager.defaultManager().URLsForDirectory(.ApplicationSupportDirectory, inDomains: .UserDomainMask)[0] as NSURL
let newPath = path.URLByAppendingPathComponent(fileName)
Alamofire.download(.GET, "https://httpbin.org/stream/100", destination: { _ in
newPath //You have to give the destination in this closure. We could say 'return newPath' instead, they're the same thing.
})
.progress({ _ in
//progress stuff
})
.response { _, _, data, _ in
//Handle response once it's all over
}
In reviewing the SwiftyDropbox tutorial in the v2 Dropbox API, it shows how to perform a download:
// Download a file
let destination : (NSURL, NSHTTPURLResponse) -> NSURL = { temporaryURL, response in
let fileManager = NSFileManager.defaultManager()
let directoryURL = fileManager.URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)[0]
// generate a unique name for this file in case we've seen it before
let UUID = NSUUID().UUIDString
let pathComponent = "\(UUID)-\(response.suggestedFilename!)"
return directoryURL.URLByAppendingPathComponent(pathComponent)
}
client.files.download(path: "/MyFile.db", destination: destination).response { response, error in
if let (metadata, url) = response {
print("*** Download file ***")
let data = NSData(contentsOfURL: url)
print("Downloaded file name: \(metadata.name)")
print("Downloaded file url: \(url)")
print("Downloaded file data: \(data)")
} else {
print(error!)
}
}
I'm unclear what's going on with the destination part. Why do I need to generate a random string for the filename?
When I try to specify my own filename, the download doesn't seem to work:
let destination : (NSURL, NSHTTPURLResponse) -> NSURL = { temporaryURL, response in
let directoryURL = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)[0]
return directoryURL.URLByAppendingPathComponent("MyFile.db")
}
I want to download a file from Dropbox named MyFile.db and I want to put it in my device's documents directory with the name MyFile.db and overwrite it if it's already there.
How can I do that?
When you say it doesn't seem to work, I expect you mean you get an error like this:
Error Domain=NSCocoaErrorDomain Code=516 "“CFNetworkDownload_bPYhu1.tmp” couldn’t be moved to “Documents” because an item with the same name already exists." UserInfo={NSSourceFilePathErrorKey=..., NSUserStringVariant=(
Move
), NSDestinationFilePath=..., NSUnderlyingError=0x7fda0a67cea0 {Error Domain=NSPOSIXErrorDomain Code=17 "File exists"}}
SwiftyDropbox, by virtue of using AlamoFire, doesn't currently let you overwrite files using the download function.
Specifically, SwiftyDropbox calls download in AlamoFire, and AlamoFire calls NSFileManager.moveItemAtURL. The documentation for NSFileManager.moveItemAtURL says:
If an item with the same name already exists at dstURL, this method aborts the move attempt and returns an appropriate error.
So, it seems like it's just being cautious, and making it hard for your app to accidentally overwrite (ad potentially lose) data. If you definitely know you want to overwrite a particular file, you'll need to do so explicitly, after the Dropbox API call. We'll consider this a feature request though.
Update: SwiftyDropbox now offers the ability to overwrite the files directly as of version 3.1.0, e.g., using download(path:rev:overwrite:destination:).