An app I'm building needs to periodically check a known location for an updated file. It happens to be a PDF. If x amount of time has passed, the app needs to upload a new copy of the file. The following code snippet works. It downloads the file. But the app displays a cached version of the PDF instead of the new one. I confirmed this by looking in the app bundle. After this code runs, there is definitely a new file in the Documents directory. But in the bundle's tmp/DiskImageCache-[random gibberish string] there is a copy of the old version of the PDF - and that is what is being displayed by my UIWebView.
I searched the NSFileManager docs and of course, schmoogled up a storm, but I have not been able to find a way to get the app to show the new upload instead of the cached version of the PDF.
Thanks a ton for any assistance you can render with this problem.
-(void) checkFile:(NSString *)url andSaveTo:(NSString __autoreleasing *)filename {
NSFileManager *manager = [NSFileManager defaultManager];
NSError *error = nil;
NSDictionary *attributes = nil;
if ([manager fileExistsAtPath:filename]) {
attributes = [manager attributesOfItemAtPath:filename error:nil];
double updateInterval = [[attributes fileCreationDate] timeIntervalSinceNow];
cacheInterval = CacheInterval;
if (ABS(updateInterval) > CacheInterval) {
[self downloadFile:url andSaveTo:fileName];
}
}
}
you can always thwart caching by appending a random number to your url as a parameter
ex: address/yourfilehere.pdf?rand=0323094230948203984
and give your long random parameter a new randomly generated number each time
Related
We've written a media application that allows you to get a list of latest videos as json list using BACKGROUND FETCH
then it uses BACKGROUND TRANSFER to tell iOS to download the video one by one and go back to sleep and to wake the app when its done.
It does all that but we've noticed that Space Usage is growing and growing.
We added code to clear all downloaded videos but space usage stayed hi in settings.
We downloaded the app folders using Xcode > Organizer> Devices and found the BACKGROUND TRANSFER tmp folder was dull of tmp files.
Shouldn't these be getting cleared out
This is in general the code I use.
I think the main is I attach multiple DownloadTask(can be up to 30) to one background session. files vary in size from movies to pdfs.
NSURLSession * backgroundSession_ = [NSURLSessionConfiguration backgroundSessionConfigurationWithIdentifier:identifier];
backgroundSession_ = [NSURLSession sessionWithConfiguration:urlSessionConfigurationBACKGROUND_
delegate:self
delegateQueue:[NSOperationQueue mainQueue]];
NSOperationQueue *mainQueue_ = [NSOperationQueue mainQueue];
NSURLSessionDownloadTask * downloadTask_ = [backgroundSession_ downloadTaskWithURL:url_];
downloadStarted_ = TRUE;
[downloadTask_ resume];
Try something like this before returning from didFinishDownloadingToURL:
// App's Documents directory path
NSString *docsPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)firstObject];
// Creating the path for the downloaded file
docsPath = [docsPath stringByAppendingPathComponent:downloadTask.response.suggestedFilename];
// Moving the file from temp location to App's Documents directory
[[NSFileManager defaultManager] moveItemAtPath:location.path toPath:docsPath error:NULL];
The documentation states that you should "move the file to a permanent location in your app’s sandbox container directory before returning from this delegate method" (perhaps the Documents directory).
The temp files that gets cleared out after you return from didFinishDownloadingToURL (or if the download failed) - at the OS's discretion (usually under memory pressure).
I have the same issue but in a bit different circumstances:
on older devices (iPhone 4S or older) the app is usually killed during the background fetching by the OS. Probably to free memory. In this case the tmp files are retained (and untracked). Next time the app has an opportunity to fetch, new files are created... and this cycle goes on and on till the user recognises the app uses 4gb of storage space - and deletes it.
I haven't found the perfect solution yet - even after I set the background configuration's -NSURLSessionConfiguration URLCache to a custom one (documentation says it's nil by default) with a path the same directory (defaultCacheDir/com.apple.nsurlsessiond/...) was used - but made a cleanup method and use it when I sure there is no download in progress.
+ (BOOL)clearCache:(NSError * __autoreleasing *)error
{
__block BOOL successOnLegacyPath = NO;
__block NSError *errorOnLegacyPath = nil;
NSString *cacheDirPath = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];
NSArray *allSubPaths = [[NSFileManager defaultManager] subpathsAtPath:cacheDirPath];
if (!allSubPaths) {
NSLog(#"No subpaths of cache:\n%#", cacheDirPath);
} else {
[allSubPaths enumerateObjectsUsingBlock:^(NSString *subpath, NSUInteger idx, BOOL *stop) {
static NSString * const kNSURLSessionPathComponent = #"nsurlsession"; // this is a non-documented way, Uncle Apple can change the path at any time
if ([subpath containsString:kNSURLSessionPathComponent]) {
successOnLegacyPath = [[NSFileManager defaultManager] removeItemAtPath:[cacheDirPath stringByAppendingPathComponent:subpath]
error:&errorOnLegacyPath];
if (!successOnLegacyPath) {
NSLog(#"Error while deleting cache subpath:\n%#\nError:\n%#", subpath, errorOnLegacyPath);
}
// First we find is the root > bail out
*stop = YES;
}
}];
}
if (!successOnLegacyPath && !errorOnLegacyPath) {
// Couldn't find the nsurlsession's cache directory
if (error) *error = [NSError errorWithDomain:NSCocoaErrorDomain
code:NSFileNoSuchFileError
userInfo:nil];
// OR
successOnLegacyPath = YES;
}
return successOnLegacyPath;
}
This is not a solution and this is recommended to use if no download is in progress. Haven't tested what's happening if there are running downloads and trying to delete the tmp files.
Even if I find a solution, the previously created tmp files still remain untracked so those need to be deleted by a method like this.
Btw, this seems to be the same question - without conclusion.
I have a folder in image.xcassets which has more than 50 images for both iPhone and iPad.
I don't want to hard code all the names programatically. Can I get the list of images in that folder in an NSArray?
I'm not sure if this fully answers your question, but should you normally do this with the method
- (NSArray *)contentsOfDirectoryAtURL:(NSURL *)url includingPropertiesForKeys:(NSArray *)keys options:(NSDirectoryEnumerationOptions)mask error:(NSError **)error ?
This is a code snippet from a program I wrote to get all the images from a directory:
-(void)getContentOfImageDirectory
{
//Emptying the image directory content array
[_imageDirectoryContent removeAllObjects];
//Using NSFileManager to load the content of the image directory in a temporary array
NSFileManager *fm = [NSFileManager defaultManager];
NSArray *tempArray = [fm contentsOfDirectoryAtURL: _imageDirectory includingPropertiesForKeys: _imageProperties options: NSDirectoryEnumerationSkipsPackageDescendants error: nil];
//Copy the temporary array into the imageDirectoryContent before returning the NSMutableArray imageDirectoryContent
[_imageDirectoryContent addObjectsFromArray:tempArray];
}
The variable _imageProperties is just an array of "common file system resource keys" as Apple calls them. The variable _imageDirectory is the URL from which you want to get the files.
hope this helps.
I'm sorry to annoy you and misunderstood your question. However, if I use the URL file///User/<Your Userid>/your file path to the program/Images.xcassets/ I get the content of that directory.
On the other hand if I use URLsForDirectory:NSApplicationDirectory inDomains:NSUserDomainMask
and then
URLByAppendingPathComponent:#"Your Application container/Contents/Resources"
I can read all the image files of any fully compiled and operational application. I'm not aware of determining the application's resource folder in any other way.
This is a code snippet for accessing the resources directory of the Windows 7 applications folder from parallels.
-(id)initWithStartURL
{
self = [super init];
if(self)
{
//Initiating the file manager
NSFileManager *fm = [NSFileManager defaultManager];
//Getting the applications directory
NSArray *listOfURLs = [fm URLsForDirectory:NSApplicationDirectory inDomains:NSUserDomainMask];
if([listOfURLs count] >= 1)
{
_tempDirectory = [listOfURLs objectAtIndex:0];
}
_imageDirectory = [_tempDirectory URLByAppendingPathComponent:#"Windows 7 Applications.app/Contents/Resources"];
}
return self;
}
I'm working on iOS project that supports iTunes file sharing feature. The goal is realtime tracking incoming/changed data's.
I'm using (kinda modified) DirectoryWatcher class from Apple's sample code
and also tried this source code.
The data is NSBundle (*.bundle) and some bundles are in 100-500 MB ranges, depends on its content, some video/audio stuff. The bundles has xml based descriptor file in it.
The problem is any of these codes above fires notification or whatever else when the data just started copying and but not when the copy/change/remove process finished completely.
Tried next:
checking file attributes:
NSDictionary *fileAttrs = [[NSFileManager defaultManager] attributesOfItemAtPath:[contURL path] error:nil];
BOOL fileBusy = [[fileAttrs objectForKey:NSFileBusy] boolValue];
looking for the fileSize changes:
dispatch_async(_checkQueue, ^{
for (NSURL *contURL in tempBundleURLs) {
NSInteger lastSize = 0;
NSDictionary *fileAttrs = [[NSFileManager defaultManager] attributesOfItemAtPath:[contURL path] error:nil];
NSInteger fileSize = [[fileAttrs objectForKey:NSFileSize] intValue];
do {
lastSize = fileSize;
[NSThread sleepForTimeInterval:1];
fileAttrs = [[NSFileManager defaultManager] attributesOfItemAtPath:[contURL path] error:nil];
fileSize = [[fileAttrs objectForKey:NSFileSize] intValue];
NSLog(#"doing job");
} while (lastSize != fileSize);
NSLog(#"next job");
}
);
any other solutions?
The solution above works great for bin files, but not for .bundle (as .bundle files are directory actually). In order to make it work with .bundle, you should iterate each file inside .bundle
You can use GCD's dispatch sources mechanism - using it you can observe particular system events (in your case, this is vnode type events, since you're working with file system).
To setup observer for particular directory, i used code like this:
- (dispatch_source_t) fileSystemDispatchSourceAtPath:(NSString*) path
{
int fileDescr = open([path fileSystemRepresentation], O_EVTONLY);// observe file system events for particular path - you can pass here Documents directory path
//observer queue is my private dispatch_queue_t object
dispatch_source_t source = dispatch_source_create(DISPATCH_SOURCE_TYPE_VNODE, fileDescr, DISPATCH_VNODE_ATTRIB| DISPATCH_VNODE_WRITE|DISPATCH_VNODE_LINK|DISPATCH_VNODE_EXTEND, observerQueue);// create dispatch_source object to observe vnode events
dispatch_source_set_registration_handler(source, ^{
NSLog(#"registered for observation");
//event handler is called each time file system event of selected type (DISPATCH_VNODE_*) has occurred
dispatch_source_set_event_handler(source, ^{
dispatch_source_vnode_flags_t flags = dispatch_source_get_data(source);//obtain flags
NSLog(#"%lu",flags);
if(flags & DISPATCH_VNODE_WRITE)//flag is set to DISPATCH_VNODE_WRITE every time data is appended to file
{
NSLog(#"DISPATCH_VNODE_WRITE");
NSDictionary* dict = [[NSFileManager defaultManager] attributesOfItemAtPath:path error:nil];
float size = [[dict valueForKey:NSFileSize] floatValue];
NSLog(#"%f",size);
}
if(flags & DISPATCH_VNODE_ATTRIB)//this flag is passed when file is completely written.
{
NSLog(#"DISPATCH_VNODE_ATTRIB");
dispatch_source_cancel(source);
}
if(flags & DISPATCH_VNODE_LINK)
{
NSLog(#"DISPATCH_VNODE_LINK");
}
if(flags & DISPATCH_VNODE_EXTEND)
{
NSLog(#"DISPATCH_VNODE_EXTEND");
}
NSLog(#"file = %#",path);
NSLog(#"\n\n");
});
dispatch_source_set_cancel_handler(source, ^{
close(fileDescr);
});
});
//we have to resume dispatch_objects
dispatch_resume(source);
return source;
}
I found two rather reliable (i.e. not 100% reliable but reliable enough for my needs) approaches, which only work in conjunction with polling the contents of the directory:
Check NSURLContentModificationDateKey. While the file is being transferred, this value is set to the current date. After transfer has finished, it is set to the value the original file had: BOOL busy = (-1.0 * [modDate timeintervalSinceNow]) < pollInterval;
Check NSURLThumbnailDictionaryKey. While the file is being transferred, this value is nil, afterwards it cointains a thumbnail, but probably only for file types from which the system can produce a thumbnail. Not a problem for me cause I only care about images and videos, but maybe for you. While this is more reliable than solution 1, it hammers the CPU quite a bit and may even cause your app to get killed if you have a lot of files in the import directory.
Dispatch sources and polling can be combined, i.e. when a dispatch source detects a change, start polling until no busy files are left.
I'm working on iOS project that supports iTunes file sharing feature. The goal is realtime tracking incoming/changed data's.
I'm using (kinda modified) DirectoryWatcher class from Apple's sample code
and also tried this source code.
The data is NSBundle (*.bundle) and some bundles are in 100-500 MB ranges, depends on its content, some video/audio stuff. The bundles has xml based descriptor file in it.
The problem is any of these codes above fires notification or whatever else when the data just started copying and but not when the copy/change/remove process finished completely.
Tried next:
checking file attributes:
NSDictionary *fileAttrs = [[NSFileManager defaultManager] attributesOfItemAtPath:[contURL path] error:nil];
BOOL fileBusy = [[fileAttrs objectForKey:NSFileBusy] boolValue];
looking for the fileSize changes:
dispatch_async(_checkQueue, ^{
for (NSURL *contURL in tempBundleURLs) {
NSInteger lastSize = 0;
NSDictionary *fileAttrs = [[NSFileManager defaultManager] attributesOfItemAtPath:[contURL path] error:nil];
NSInteger fileSize = [[fileAttrs objectForKey:NSFileSize] intValue];
do {
lastSize = fileSize;
[NSThread sleepForTimeInterval:1];
fileAttrs = [[NSFileManager defaultManager] attributesOfItemAtPath:[contURL path] error:nil];
fileSize = [[fileAttrs objectForKey:NSFileSize] intValue];
NSLog(#"doing job");
} while (lastSize != fileSize);
NSLog(#"next job");
}
);
any other solutions?
The solution above works great for bin files, but not for .bundle (as .bundle files are directory actually). In order to make it work with .bundle, you should iterate each file inside .bundle
You can use GCD's dispatch sources mechanism - using it you can observe particular system events (in your case, this is vnode type events, since you're working with file system).
To setup observer for particular directory, i used code like this:
- (dispatch_source_t) fileSystemDispatchSourceAtPath:(NSString*) path
{
int fileDescr = open([path fileSystemRepresentation], O_EVTONLY);// observe file system events for particular path - you can pass here Documents directory path
//observer queue is my private dispatch_queue_t object
dispatch_source_t source = dispatch_source_create(DISPATCH_SOURCE_TYPE_VNODE, fileDescr, DISPATCH_VNODE_ATTRIB| DISPATCH_VNODE_WRITE|DISPATCH_VNODE_LINK|DISPATCH_VNODE_EXTEND, observerQueue);// create dispatch_source object to observe vnode events
dispatch_source_set_registration_handler(source, ^{
NSLog(#"registered for observation");
//event handler is called each time file system event of selected type (DISPATCH_VNODE_*) has occurred
dispatch_source_set_event_handler(source, ^{
dispatch_source_vnode_flags_t flags = dispatch_source_get_data(source);//obtain flags
NSLog(#"%lu",flags);
if(flags & DISPATCH_VNODE_WRITE)//flag is set to DISPATCH_VNODE_WRITE every time data is appended to file
{
NSLog(#"DISPATCH_VNODE_WRITE");
NSDictionary* dict = [[NSFileManager defaultManager] attributesOfItemAtPath:path error:nil];
float size = [[dict valueForKey:NSFileSize] floatValue];
NSLog(#"%f",size);
}
if(flags & DISPATCH_VNODE_ATTRIB)//this flag is passed when file is completely written.
{
NSLog(#"DISPATCH_VNODE_ATTRIB");
dispatch_source_cancel(source);
}
if(flags & DISPATCH_VNODE_LINK)
{
NSLog(#"DISPATCH_VNODE_LINK");
}
if(flags & DISPATCH_VNODE_EXTEND)
{
NSLog(#"DISPATCH_VNODE_EXTEND");
}
NSLog(#"file = %#",path);
NSLog(#"\n\n");
});
dispatch_source_set_cancel_handler(source, ^{
close(fileDescr);
});
});
//we have to resume dispatch_objects
dispatch_resume(source);
return source;
}
I found two rather reliable (i.e. not 100% reliable but reliable enough for my needs) approaches, which only work in conjunction with polling the contents of the directory:
Check NSURLContentModificationDateKey. While the file is being transferred, this value is set to the current date. After transfer has finished, it is set to the value the original file had: BOOL busy = (-1.0 * [modDate timeintervalSinceNow]) < pollInterval;
Check NSURLThumbnailDictionaryKey. While the file is being transferred, this value is nil, afterwards it cointains a thumbnail, but probably only for file types from which the system can produce a thumbnail. Not a problem for me cause I only care about images and videos, but maybe for you. While this is more reliable than solution 1, it hammers the CPU quite a bit and may even cause your app to get killed if you have a lot of files in the import directory.
Dispatch sources and polling can be combined, i.e. when a dispatch source detects a change, start polling until no busy files are left.
I'm trying to copy a downloaded file to a specific folder in the app's documents directory but can't seem to get it working. The code I'm using is:
NSString *itemPathString = #"http://pathToFolder/folder/myFile.doc";
NSURL *myUrl = [NSURL URLWithString:itemPathString];
NSArray *paths = [fm URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask];
NSURL *folderPath = [[paths objectAtIndex:0] URLByAppendingPathComponent:#"folder"];
NSURL *itemURL = [documentsPath URLByAppendingPathComponent:#"myFile.doc"];
// copy to documents directory asynchronously
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
NSFileManager *theFM = [[NSFileManager alloc] init];
NSError *error;
[theFM copyItemAtURL:myUrl toURL:itemURL error:&error];
}
});
I can retrieve the file OK but can't copy it. Can anyone tell me if there's anything wrong with the above code?
If downloading a file from a server, if it's a reasonably small file (e.g. measured in kb, not mb), you can use dataWithContentsOfURL. You can use that method to load the file into memory, and then use the NSData instance method writeToFile to save the file.
But, if it's a larger file, you will want to use NSURLConnection, which doesn't try to hold the whole file in memory, but rather writes it to the file system when appropriate. The trick here, though, is if you want to download multiple files, you either have to download them sequentially, or encapsulate the NSURLConnection and the NSOutputStream such that you can have separate copies of those for each simultaneous download.
I have uploaded a project, Download Manager that demonstrates what a NSURLConnection implementation might look like, but it's non-trivial. You might rather want to contemplate using an established, third-party library, such as ASIHTTPRequest or RestKit.
If you want to access a folder with a given name you should check if it exists and if not create it. That could quite easy be done like this:
NSString *folder = [documentsPath stringByAppendingPathComponent:folderName];
NSFileManager *fileManager = [NSFileManager defaultManager];
NSError *error = nil;
if (![fileManager fileExistsAtPath:folder]) {
[fileManager createDirectoryAtPath:folder withIntermediateDirectories:YES attributes:nil error:&error];
}
if (error != nil) {
NSLog(#"Some error: %#", error);
return;
}
EDIT
If you want to check if the folder was created properly on your device got to Organizer -> Devices -> [YourDevelopingDeviceWhereTheAppWasInstalled] -> Applications -> [YourApplication]
In the lower section you should at least see some folders like Documents. And if successful your created folders as well.
You need to create any intermediate directories prior to copying files. Check in the Simulator folder to see wether the "folder" directory is created in the applications Documents-folder.
Path to simulator is /Users/$username/Library/Application Support/iPhone Simulator/