iphone download several files - iphone

In my app i need to download several plist. 
to download a plist i use the NSURLconnection 
in my code i use an UIAlertView with a UIActivityIndicator then when the download is finished i add a button to the alert to dismiss it. 
To download the plist i use somewhere in my code an NSURL set to the adresse where the plist is, next i set a NSURLRequest with the url cache policy and a timeout interval. 
Then i set my NSMutableData to the NSURL connection with a NSURLRequest. 
In the delegate didReceiveData: i append data to my mutable data object, in the didFailWithError: i handle error. And finaly in the connectionDidFinishLoading  i serialize my data to a plist so i can write to file my plist, and release my alertview. 
My problem is : how can i do if i have sevetal file to download because the connectionDidFinishLoading is called each time my NSURLConnection is finished but i want to release my UiAlert when everything is finished. But when the first plist is downloaded my code in the connectionDidFinishLoading will fire. 
here is my code : 
in the view did load : 
// set the UiAlert in the view did load 
NSURL *theUrl = [NSURL URLWithString:#"http://adress.com/plist/myPlist.plist"];
NSURLRequest *theRequest = [NSURLRequest requestWithURL:theUrl cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:60.0];
self.plistConnection = [[ NSURLConnection alloc] initwithRequest:theRequest delegate:self startImmediatly:YES];
//plistConnection is a NSURLConnection
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data { 
[incomingPListData appendData:data];
}
-(void)connection:(NSURLConnection *)connectionDidFailWithError:(NSError *)error {
// handle error here 
}
-(void)connectionDidFinisloading:(NSURLConnection *) connection { 
NSPropertyListFormat format;
NSString *serialErrorString; 
NSData *plist = [NSPropertyListSerialisation propertyListFromData:incomingPlistData mutabilityOption:NSPropertyListImmutable format:&format errorDescription:&serialErrorString];
if (serialErrorString) {//error}
else { // create path and write plist to path}
// change message and title of the alert
so if i want todownload an another file  where do i put the request the connection and how can i tell the didFinishLoading to fire code when all my file are downloaded. 
thanks to all 

You can iterate over an array of resources you wish to download, and allocate a request for each of them. It is possible to set a tag to a connection (e.g. the index of the URL in the array) which you can evaluate in the connectionDidFinishLoading. If you hold the information, which requests are sent and which are finished, you can easily see, if all files have been loaded.

I think unset provided a good answer. I understand that you don't get it (you will someday), as I remember myself being new to programming and such.
I therefore provide another, much simpler option to evaluate if all downloads did finish.
you simply use a counter that you define in your .h file,
int activeDownloads;
in your implementation (.m) File, wherever you start all your downloads, set activeDownloads to zero before any of your downloads start
activeDownloads = 0;
before you start a download you increase the number of activeDownloads
++activeDownloads;
if a download finishes or fails you decrease the same countervariable
- (void)connectionDidFinishLoading:(NSURLConnection *)connection { --activeDownloads;}
(i didn't write down the method that gets called if a download fails...
also everytime a connection finishes or fails you have to check if the one that finished or railed was the last one.
you do that by simply checking if activeDownloads is equal to zero. If that is the case, you can add the "close" Button to your AlertView.
The drawback of this solution is, that you're unable to track which connection succeeded and which failed. (well, you are, but activeDownloads don't help you with that)
hope i could help
cheers

Related

Showing Accurate Progress In UIProgressView While Downloading Images in iphone

I have four urls which consists images...
I'm downloding those images and placing them into documents folder..
here is my code..
-(void)viewDidLoad
{
NSMutableArray *myUrlsArray=[[NSMutableArray alloc]init];
[myUrlsArray addObject:#"http://blogs.sfweekly.com/thesnitch/steve_jobs3.jpg"];
[myUrlsArray addObject:#"http://www.droid-life.com/wp-content/uploads/2012/12/Steve-Jobs-Apple.jpg"];
[myUrlsArray addObject:#"http://2.bp.blogspot.com/-T6nbl0rQoME/To0X5FccuCI/AAAAAAAAEZQ/ipUU7JfEzTs/s1600/steve-jobs-in-time-magazine-front-cover.png"];
[myUrlsArray addObject:#"http://images.businessweek.com/ss/08/09/0929_most_influential/image/steve_jobs.jpg"];
[myUrlsArray addObject:#"http://cdn.ndtv.com/tech/gadget/image/steve-jobs-face.jpg"];
for (int i=0; i<myUrlsArray.count; i++)
{
[self downloadImageFromURL:[myUrlsArray objectAtIndex:i] withName:[NSString stringWithFormat:#"MyImage%i.jpeg",i]];
}
}
#pragma mark- downloading File
-(void)downloadImageFromURL:(NSString *)myURLString withName:(NSString *)fileName
{
UIImage *image = [[UIImage alloc] initWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:myURLString]]];
NSLog(#"%f,%f",image.size.width,image.size.height);
// Let's save the file into Document folder.**
NSString *documentsPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask, YES) objectAtIndex:0];
NSString *jpegPath = [NSString stringWithFormat:#"%#/%#",documentsPath,fileName];// this path if you want save reference path in sqlite
NSData *data2 = [NSData dataWithData:UIImageJPEGRepresentation(image, 1.0f)];//1.0f = 100% quality
[data2 writeToFile:jpegPath atomically:YES];
}
NOW... I need to display a UIProgressView for above downloading progress accurately.
how can i achieve this functionality...
Can any one provide some guidelines to achieve this..
Thanks in advance...
I'd suggest you use some asynchronous downloading technique (either AFNetworking, SDWebImage, or roll your own with delegate-based NSURLSession) rather than dataWithContentsOfURL so that (a) you don't block the main queue; and (b) you can get progress updates as the downloads proceed.
I'd also suggest creating a NSProgress for each download. When your delegate method gets updates about how many bytes have been downloaded, update the NSProgress object.
You then can associate each NSProgress with a observedProgress for a UIProgressView, and when you update your NSProgress, the UI can be updated automatically.
Or, if you and a single UIProgressView to show the aggregate progress of all of the NSProgress for each download, you can create a parent NSProgress, establish each download's NSProgress as a child of the parent NSProgress, and then, as each download updates its respective NSProgress, this will automatically trigger the calculation of the parent NSProgress. And again, you can tie that parent NSProgress to a master UIProgressView, and you'll automatically update the UI with the total progress, just by having each download update its individual NSProgress.
There is a trick, though, insofar as some web services will not inform you of the number of bytes to be expected. They'll report an "expected number of bytes" of NSURLResponseUnknownLength, i.e. -1! (There are logical reasons why it does that which are probably beyond the scope of this question.) That obviously makes it hard to calculate what percentage has been downloaded.
In that case, there are a few approaches:
You can throw up your hands and just use an indeterminate progress indicator;
You can try changing the request such that web service will report meaningful "expected number of bytes" values (e.g. https://stackoverflow.com/a/22352294/1271826); or
You can use an "estimated download size" to estimate the percentage completion. For example, if you know your images are, on average, 100kb each, you can do something like the following to update the NSProgress associated with a particular download:
if (totalBytesExpectedToWrite >= totalBytesWritten) {
self.progress.totalUnitCount = totalBytesExpectedToWrite;
} else {
if (totalBytesWritten <= 0) {
self.progress.totalUnitCount = kDefaultImageSize;
} else {
double written = (double)totalBytesWritten;
double percent = tanh(written / (double)kDefaultImageSize);
self.progress.totalUnitCount = written / percent;
}
}
self.progress.completedUnitCount = totalBytesWritten;
This is a bit of sleight of hand that uses the tanh function to return a "percent complete" value that smoothly and asymptotically approaches 100%, using the kDefaultImageSize as the basis for the estimation.
It's not perfect, but it yields a pretty decent proxy for percent completion.
Your call to dataWithContentsOfURL is synchronous, meaning you don't get updates as the download is in process.
You can use a library like AFNetworking (https://github.com/AFNetworking/AFNetworking) which has callbacks to the progress of the download.
Actually a better solution is to use SDWebImage manager which will load the images in the background for you and cache them. Then the next time you use that image it will check the cache. Google it.
That way the user also doesn't have to sit around and wait while you're downloading stuff..
Then look at this other question that has some ideas on how to do a status:
How to show an activity indicator in SDWebImage
Do not use dataWithContentsOfURL, you are blocking the main thread until the data arrives.
Instead create your own connection with NSURLConnection and start listening to your delegate.
connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response: get the total data size with [response expectedContentLength].
connection:(NSURLConnection *)connection didReceiveData:(NSData *)data: This is where you do your calculations and update your UIProgressView. Something like, loadedBytes/total data size.
Good luck.

How store a video while streaming that? [duplicate]

So far I know how to stream a video and how to download it and afterwards stream it, but here's the tricky bit: streaming it once, storing it on the device and in the future play it from the device.
Is that possible?
Not quite sure here how you get your stream but look in to the AVAssetWriter, AVAssetWriterInput and AVAssetWriterPixelBufferAdaptor and as soon as you receive data you should be able to append the data to the to the pixel buffer adaptor using:
appendPixelBuffer:withPresentationTime:
not sure it will work for you but with some fiddling you should be able to adapt your input to match this method. There are lots of example code for setting up the writer
It's quite easy to save the video. Do something similar to this:
//Saving Movie
NSMutableData *data = [[NSMutableData alloc] init];
NSKeyedArchiver *archiver = [[NSKeyedArchiver alloc] initForWritingWithMutableData:data];
[archiver encodeObject:*MovieObject* forKey:#"MovieObjectDataKey"];
[archiver finishEncoding];
[[NSUserDefaults standardUserDefaults] setObject:data forKey:#"MovieObjectDefaultsDataKey"];
[archiver release];
[data release];
//Retrieving movie
NSData *savedMovieData = [[NSUserDefaults standardUserDefaults] objectForKey:#"MovieObjectDefaultsDataKey"];
if (savedMovieData != nil) {
NSKeyedUnarchiver *unarchiver = [[NSKeyedUnarchiver alloc] initForReadingWithData:savedMovieData];
*MovieObject* = [[unarchiver decodeObjectForKey:#"MovieObjectDataKey"] retain];
[unarchiver finishDecoding];
[savedMovieData release];
[unarchiver release];
} else {
//Download Stream of Your Movie
}
The only thing you really have to change there is * MovieObject *, once in each step.
I know what you want to achieve, I only got a workaround. I had to implement the same behavior and ended up with streaming the video from the server and downloading it next to streaming. Next time the user tries to stream the video determine whether it was downloaded to disk, otherwise stream it again. In a normal case the video was downloaded properly and could be reviewed offline.
BOOL fileExists = [[NSFileManager defaultManager] fileExistsAtPath:somePath];
and
fileURLWithPath:isDirectory:
Initializes and returns a newly created NSURL object as a file URL with a specified path.
+ (id)fileURLWithPath:(NSString *)path isDirectory:(BOOL)isDir
Parameters
path
The path that the NSURL object will represent. path should be a valid system path. If path begins with a tilde, it must first be expanded with stringByExpandingTildeInPath. If path is a relative path, it is treated as being relative to the current working directory.
Passing nil for this parameter produces an exception.
isDir
A Boolean value that specifies whether path is treated as a directory path when resolving against relative path components. Pass YES if the path indicates a directory, NO otherwise.
Return Value
An NSURL object initialized with path.
Availability
Available in iOS 2.0 and later.
You can't stream it and save it at the same time, especially with large video files as the Apple doc sais that you must use a transport stream for HTTP Live Streaming.
ASIHttpRequest might make your life easier.
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
[request setDownloadDestinationPath:#"video.m4v"]; // use [NSBundle mainBundle] to find a better place
From your delegate, handle this:
- (void)request:(ASIHTTPRequest *)request didReceiveData:(NSData *)data;
Do whatever data transcoding with data as you get it and push it off to your AVAssetWriter or movie player layer in real time, whatever you are using. When you're done, the asset should still be saved so you can get it later.

ASIHTTPRequest for download documents fail second time

I'm using ASIHTTP for download some documents from a server. I have a button that first control the differences between the local version (saved on iPad file system) and the server version and then (after a confirm alert view) starts the downloads.
To download the documents I use this code:
for (SyncNode *node in _syncDocuments) {
//SyncNode is a my Class that handle document
// start the download
NSString *filename = [NSString stringWithFormat:#"%#.%#",node.uniqueIdentifier,node.extension];
NSString *tempPath = [SavedDocument pathToSyncFile:filename];
// tempPath is a string like this
// /var/mobile/Applications/5C05AA6F-55B3-46FD-8330-094BD0E61973/Documents/SyncDocumentsFolder/D49B421C-7528-4A3D-A8F6-942FF03881D0/f2e650e2-cff7-4485-9152-5445bee436f2.jpg
//BaseHTTPRequest is an extension of ASIHTTPRequest
BaseHTTPRequest *request = [[[BaseHTTPRequest alloc] initWithURL:[NSURL URLWithString:node.contentLocation] accountUUID:_uuid] autorelease];
request.userInfo = [NSDictionary dictionaryWithObject:[NSNumber numberWithInt:i+1] forKey:#"requestNumber"];
[request setDelegate:self];
[request setShowAccurateProgress:YES];
[request setDownloadProgressDelegate:self];
[request setDownloadDestinationPath:tempPath];
[request startAsynchronous];
}
Scenario.
I don't have any local file stored on iPad
I push the button and the routine calculate the size of the download
I accept the download and a routine dowloads all documents. When I try to display one of this documents (in a web view) it works fine and I can see the document.
I delete all local documents (the delete process works perfectly, in fact the documents exists on the file system).
Now, I'am in the same situation of 1. but when I try to dowload the same documents again (the second time) all ASIHTTPRequest return and call my - (void)requestFinished:(ASIHTTPRequest *)request method, in a very short time interval.
Example: I have a directory with 8MB of documents; the first time the routine needs 11 or 12 seconds to complete all download. Instead the second time the same routine, with the same documents needs less than 1 second to complete all downloads.
It's seem that the download not run, but ASIHTTP doesn't call any error delegate methods.
When I try to show a document downloaded (the second time) I see this error message in the console:
Error copying file to temp path Error Domain=NSCocoaErrorDomain Code=260 "The operation
couldn’t be completed. (Cocoa error 260.)" UserInfo=0x1229e900
{NSFilePath=/var/mobile/Applications/5C05AA6F-55B3-46FD-8330-
094BD0E61973/Documents/SyncDocumentsFolder/D49B421C-7528-4A3D-A8F6-942FF03881D0/f2e650e2-cff7-
4485-9152-5445bee436f2.jpg, NSUnderlyingError=0x1229e570 "The operation couldn’t be completed.
No such file or directory"}
This problem drive me crazy !
Any ideas ?
Try to set a cache policy for your request using setCachePolicy propery.
[request setCachePolicy:(ASIDoNotReadFromCacheCachePolicy | ASIDoNotWriteToCacheCachePolicy)];
For more informations read this: http://allseeing-i.com/ASIHTTPRequest/How-to-use#using_a_download_cache

NSURLConnection and Content-Encoding

I have an NSURLConnection which is downloading a web page. I get the Content-Length which is much smaller than the actual size of the file.
I noticed that the header also says:
Content-Encoding:gzip
I guess the size returned by Content-Length is the compressed size, however the NSData returned by NSURLConnection has been decompressed.
Firstly does NSURLConnection automatically decompress it?
And how do I get the length of either the uncompressed file (instead of Content-Length)
If you need a progress bar, why not try ASIHTTPRequest? It has a number of built in features that help manage a progress bar.
If what you're trying to do is make some sort of progress bar or progress indicator for an NSURLConnection download, try the below code. It works like a charm in a few of my apps.
- (void) connection:(NSURLConnection *)connection didReceiveData:(NSData *)data {
// append the new data to receivedData (a global variable).
[receivedData appendData:data];
// calculate number of kilobytes
int kb = [receivedData length] / 1024;
// update a label, or some other visula thingy
self.downloadProgressLabel.text = [NSString stringWithFormat:#"Downloaded\n%d kB", kb];
}

concurrent background downloads on iphone

I am trying to create class that will handle multiple downloads at same time (I need to download a lot of small files) and I have problems with "disappearing" connections.
I have function addDonwload that adds url to list of urls to download, and checks if there is free download slot available. If there is one it starts download immediately. When one of downloads finishes, I pick first url form list and start new download.
I use NSURLConnection for downloading, here is some code
- (bool) TryDownload:(downloadInfo*)info
{
int index;
#synchronized(_asyncConnection)
{
index = [_asyncConnection indexOfObject:nullObject];
if(index != NSNotFound)
{
NSLog(#"downloading %# at index %i", info.url, index);
activeInfo[index] = info;
NSURLRequest *request = [NSURLRequest requestWithURL:info.url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:15];
[_asyncConnection replaceObjectAtIndex:index withObject:[[NSURLConnection alloc] initWithRequest:request delegate:self startImmediately:TRUE]];
//[[_asyncConnection objectAtIndex:i] scheduleInRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];
return true;
}
}
return false;
}
- (void)connectionDidFinishLoading:(NSURLConnection*)connection
{
[self performSelectorOnMainThread:#selector(DownloadFinished:) withObject:connection waitUntilDone:false];
}
- (void)DownloadFinished:(id)connection
{
NSInteger index = NSNotFound;
#synchronized(_asyncConnection)
{
index = [_asyncConnection indexOfObject:(NSURLConnection*)connection];
}
[(id)activeInfo[index].delegate performSelectorInBackground:#selector(backgroundDownloadSucceededWithData:) withObject:_data[index]];
[_data[index] release];
[activeInfo[index].delegate release];
#synchronized(_asyncConnection)
{
[[_asyncConnection objectAtIndex:index] release];
[_asyncConnection replaceObjectAtIndex:index withObject:nullObject];
}
#synchronized(downloadQueue)
{
[downloadQueue removeObject:activeInfo[index]];
[self NextDownload];
}
}
- (void)NextDownload
{
NSLog(#"files remaining: %i", downloadQueue.count);
if(downloadQueue.count > 0)
{
if([self TryDownload:[downloadQueue objectAtIndex:0]])
{
[downloadQueue removeObjectAtIndex:0];
}
}
}
_asyncConnection is my array of download slots (NSURLConnections)
downloadQueue is list of urls to download
What happens is, at the beginning everything works ok, but after few downloads my connections start to disappear. Download starts but connection:didReceiveResponse: never gets called. There is one thing in output console that I don't understand I that might help a bit. Normaly there is something like
2010-01-24 21:44:17.504 appName[3057:207]
before my NSLog messages. I guess that number in square brackets is some kind of app:thread id? everything works ok while there is same number, but after some time, "NSLog(#"downloading %# at index %i", info.url, index);" messages starts having different that second number. And when that happens, I stop receiving any callbacks for that urlconnection.
This has been driving me nuts as I have strict deadlines and I can't find problem. I don't have many experiences with iphone dev and multithreaded apps. I have been trying different approaches so my code is kinda messy, but I hope you will see what I am trying to do here :)
btw is anyone of you know about existing class/lib I could use that would be helpful as well. I want parallel downloads with ability o dynamically add new files to download (so initializing downloader at the beginning with all urls is not helpful for me)
You've got a bunch of serious memory issues, and thread synchronization issues in this code.
Rather than go into them all, I'll ask the following question: You are doing this on a background thread of some kind? Why? IIRC NSURLConnection already does it's downloads on a background thread and calls your delegate on the thread that the NSURLConnection was created upon (e.g., your main thread ideally).
Suggest you step back, re-read NSURLConnection documentation and then remove your background threading code and all the complexity you've injected into this unnecessarily.
Further Suggestion: Instead of trying to maintain parallel positioning in two arrays (and some sketchy code in the above relating to that), make one array and have an object that contains both the NSURLConnection AND the object representing the result. Then you can just release the connection instance var when the connection is done. And the parent object (and thus the data) when you are done with the data.
I recommend that you take a look at this:
http://allseeing-i.com/ASIHTTPRequest/
It's a pretty sophisticated set of classes with liberal licensing terms (free too).
It may provide a lot of the functionality that you are wanting.
This snippet can be the source of the bug, you release the object pointed to by the activeInfo[index].delegate pointer right after issuing async method call on that object.
[(id)activeInfo[index].delegate performSelectorInBackground:#selector(backgroundDownloadSucceededWithData:) withObject:_data[index]];
[_data[index] release];
[activeInfo[index].delegate release];
Do you use connection:didFailWithError: ? There may be a timeout that prevents the successful download completion.
Try to get rid of the #synchronized blocks and see what happens.
The string inside the square brackets seems to be thread identifier as you guessed. So maybe you get locked in the #synchronized. Actually, I don't see a reason for switching thread - all the problematic code should run in the main thread (performSelectorOnMainThread)...
Anyhow, there is no need to use both the #synchronized and the performSelectorOnMainThread.
BTW, I didn't see the NSURLConnection *connection = [[NSURLConnection alloc] initWithRequest:request delegate:self]; line. Where do you initiate the connection?
As for the parallel downloads - I think that you can download more than one file in a time with the same code that you use here. Just create a separate connection for each download.
Consider just keeping a download queue along with a count of active connections, popping items off the top of the queue when downloads complete and a slot becomes free. You can then fire off NSURLConnection objects asynchronously and process events on the main thread.
If you find that your parallel approach prohibits doing all of the processing on the main thread, consider having intermediary manager objects between your main thread download code and NSURLConnection. Using that approach, you'd instantiate your manager and get it to use NSURLConnection synchronously on a background thread. That manager then completely deals with the downloading and passes the result back to its main thread delegate using a performSelectorOnMainThread:withObject: call. Each download is then just a case of creating a new manager object when you've a slot free and setting it going.