I have this code that saves a JSON file:
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
tabController = [self.storyboard instantiateViewControllerWithIdentifier:#"cCustomTabController"];
dValue = [dConfiguration objectForKey:#"Buttons"];
int i = 0;
for (NSString* sProperty in dValue) {
NetworkStatus internetStatus = [_reachabilityInfo currentReachabilityStatus];
NSData *itemData = Nil;
if (internetStatus != NotReachable)
itemData = [util getSpecificJsonData:[sProperty valueForKeyPath:#"Item"]];
if(itemData != nil){
[util saveJSON:itemData withName:[NSString stringWithFormat:#"%#%#",[sProperty valueForKeyPath:#"Item"],[CommonsUtils getCommonUtil].getAppLanguage]];
i++;
}
}
});
Let's say that I use this JSON to configure my next screen, so in my bundle I already have a JSON file to avoid the file does not exist but I always update it from the server to have the last configuration possible.
My problem is the sometimes it takes a while to save or download the file and my next screen goes black because it does not get the file property, so is my guess that the file at that moment is being written.
So my question is if there is a way to know if the file is being written or there is a workaround to confirm that the file is some how accesible to then read it.
This is an example of what I do when I read the file:
if (_JsonData == nil) {
NSString *jsonPath = [NSString stringWithFormat:#"%#/%#.json",[NSSearchPathForDirectoriesInDomains (NSDocumentDirectory,NSUserDomainMask, YES) objectAtIndex:0],_JsonConfigFile];
_JsonData = [NSData dataWithContentsOfFile:jsonPath];
}
if (_JsonData != nil) {
dConfiguration =[NSJSONSerialization JSONObjectWithData:_JsonData options:kNilOptions error:nil];
}
EDIT 1:
I need to use a queue to speed up things, so is necessary to my app, in fact I'm changing the code to this because the app takes too much time to get this files, it depends on the client but now one of them is pulling 7 files of configuration and the performance is bean affected.
i'm facing the same issue..
I believe the only solution is to monitor the target file path by setting up callbacks of "file was modified", waiting a short bit of time, and if you receive none... you know it's free and clear
Related
My app offers the option to download 3430 high resolution images from our server, each image of size 50k - 600k bytes.
The original approach was to just download all of them - but we realized that gave a lot of NSURLErrorTimedOut errors and crashed our program. We then implemented it such that we download all of the images, but in batches of 100 images at a time. Someone on SO suggested we actually implement our download like this:
Create a list of all file URLs that need to be downloaded.
Write your code so that it downloads these URLs sequentially. I.e. do
not let it start downloading a file until the previous one has
finished (or failed and you decided to skip it for now).
Use NSURLSession's support for downloading an individual file to a
folder, don't use the code to get an NSData and save the file
yourself. That way, your application doesn't need to be running while
the download finishes.
Ensure that you can tell whether a file has already been downloaded or
not, in case your download gets interrupted, or the phone is restarted
in mid-download. You can e.g. do this by comparing their names (if
they are unique enough), or saving a note to a plist that lets you
match a downloaded file to the URL where it came from, or whatever
constitutes an identifying characteristic in your case.
At startup, check whether all files are there. If not, put the missing
ones in above download list and download them sequentially, as in #2.
Before you start downloading anything (and that includes downloading
the next file after the previous download has finished or failed), do
a reachability check using the Reachability API from Apple's
SystemConfiguration.framework. That will tell you whether the user has
a connection at all, and whether you're on WiFi or cellular (in
general, you do not want to download a large number of files via
cellular, most cellular connections are metered).
We create a list of all images to download here:
- (void)generateImageURLList:(BOOL)batchDownloadImagesFromServer
{
NSError* error;
NSFetchRequest* leafletURLRequest = [[[NSFetchRequest alloc] init] autorelease];
NSEntityDescription* leafletURLDescription = [NSEntityDescription entityForName:#"LeafletURL" inManagedObjectContext:managedObjectContext];
[leafletURLRequest setEntity:leafletURLDescription];
numberOfImages = [managedObjectContext countForFetchRequest:leafletURLRequest error:&error];
NSPredicate* thumbnailPredicate = [NSPredicate predicateWithFormat:#"thumbnailLocation like %#", kLocationServer];
[leafletURLRequest setPredicate:thumbnailPredicate];
self.uncachedThumbnailArray = [managedObjectContext executeFetchRequest:leafletURLRequest error:&error];
NSPredicate* hiResPredicate = [NSPredicate predicateWithFormat:#"hiResImageLocation != %#", kLocationCache];
[leafletURLRequest setPredicate:hiResPredicate];
self.uncachedHiResImageArray = [managedObjectContext executeFetchRequest:leafletURLRequest error:&error];
}
We use NSURLSession to download an individual image to a folder by calling hitServerForUrl and implementing didFinishDownloadingToURL:
- (void)hitServerForUrl:(NSURL*)requestUrl {
NSURLSessionConfiguration *defaultConfigurationObject = [NSURLSessionConfiguration defaultSessionConfiguration];
NSURLSession *defaultSession = [NSURLSession sessionWithConfiguration:defaultConfigurationObject delegate:self delegateQueue: nil];
NSURLSessionDownloadTask *fileDownloadTask = [defaultSession downloadTaskWithURL:requestUrl];
[fileDownloadTask resume];
}
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didFinishDownloadingToURL:(NSURL *)location {
if (isThumbnail)
{
leafletURL.thumbnailLocation = kLocationCache;
}
else
{
leafletURL.hiResImageLocation = kLocationCache;
}
// Filename to write to
NSString* filePath = [leafletURL pathForImageAtLocation:kLocationCache isThumbnail:isThumbnail isRetina:NO];
// If it's a retina image, append the "#2x"
if (isRetina_) {
filePath = [filePath stringByReplacingOccurrencesOfString:#".jpg" withString:#"#2x.jpg"];
}
NSString* dir = [filePath stringByDeletingLastPathComponent];
[managedObjectContext save:nil];
NSError* error;
[[NSFileManager defaultManager] createDirectoryAtPath:dir withIntermediateDirectories:YES attributes:nil error:&error];
NSURL *documentURL = [NSURL fileURLWithPath:filePath];
NSLog(#"file path : %#", filePath);
if ([[NSFileManager defaultManager] fileExistsAtPath:filePath]) {
//Remove the old file from directory
}
[[NSFileManager defaultManager] moveItemAtURL:location
toURL:documentURL
error:&error];
if (error){
//Handle error here
}
}
This code calls loadImage, which calls `hitServer:
-(void)downloadImagesFromServer{
[self generateImageURLList:NO];
[leafletImageLoaderQueue removeAllObjects];
numberOfHiResImageLeft = [uncachedHiResImageArray count];
for ( LeafletURL* aLeafletURL in uncachedHiResImageArray)
{
//// Do the same thing again, except set isThumb = NO. ////
LeafletImageLoader* hiResImageLoader = [[LeafletImageLoader alloc] initWithDelegate:self];
[leafletImageLoaderQueue addObject:hiResImageLoader]; // do this before making connection!! //
[hiResImageLoader loadImage:aLeafletURL isThumbnail:NO isBatchDownload:YES];
//// Adding object to array already retains it, so it's safe to release it here. ////
[hiResImageLoader release];
uncachedHiResIndex++;
NSLog(#"uncached hi res index: %ld, un cached hi res image array size: %lu", (long)uncachedHiResIndex, (unsigned long)[uncachedHiResImageArray count]);
}
}
- (void)loadImage:(LeafletURL*)leafletURLInput isThumbnail:(BOOL)isThumbnailInput isBatchDownload:(BOOL)isBatchDownload isRetina:(BOOL)isRetina
{
isRetina_ = isRetina;
if (mConnection)
{
[mConnection cancel];
[mConnection release];
mConnection = nil;
}
if (mImageData)
{
[mImageData release];
mImageData = nil;
}
self.leafletURL = leafletURLInput;
self.isThumbnail = isThumbnailInput;
NSString* location = (self.isThumbnail) ?leafletURL.thumbnailLocation :leafletURL.hiResImageLocation;
//// Check if the image needs to be downloaded from server. If it is a batch download, then override the local resources////
if ( ([location isEqualToString:kLocationServer] || (isBatchDownload && [location isEqualToString:kLocationResource])) && self.leafletURL.rawURL != nil )
{
//NSLog(#"final loadimage called server");
//// tell the delegate to get ride of the old image while waiting. ////
if([delegate respondsToSelector:#selector(leafletImageLoaderWillBeginLoadingImage:)])
{
[delegate leafletImageLoaderWillBeginLoadingImage:self];
}
mImageData = [[NSMutableData alloc] init];
NSURL* url = [NSURL URLWithString:[leafletURL pathForImageOnServerUsingThumbnail:self.isThumbnail isRetina:isRetina]];
[self hitServerForUrl:url];
}
//// if not, tell the delegate that the image is already cached. ////
else
{
if([delegate respondsToSelector:#selector(leafletImageLoaderDidFinishLoadingImage:)])
{
[delegate leafletImageLoaderDidFinishLoadingImage:self];
}
}
}
Currently, I'm trying to figure out how to download the images sequentially, such that we don't call hitServer until the last image is finished downloading. Do I need to be downloading in the background? Thank you for suggestions!
My app offers the option to download 3430 high resolution images from our server, each image of size 50k - 600k bytes.
This seems like a job for on-demand resources. Just turn these files into on-demand resources obtained from your own server, and let the system take care of downloading them in its own sweet time.
This sounds very much like an architectural issue. If you fire off downloads without limiting them of course you're going to start getting timeouts and other things. Think about other apps and what they do. Apps that give the user the ability to do multiple downloads often limit how may can occur at once. iTunes for example can queue up thousands of downloads, but only runs 3 at a time. Limiting to just one at a time will only slow things down for your users. You need a balance that consider your user's available bandwidth.
The other part of this is to again consider what your users want. Does every one of your uses want every single image? I don't know what you are offering them, but in most apps which access resources like images or music, it's up to the user what and when they download. Thus they only download what they are interested in. So I'd recommend only downloading what the users are viewing or have somehow requested they want to download.
I've a messages app and I started to create a widget.
Updating the core data with the new messages happens when user open the app.
My wish is when:
- (void)widgetPerformUpdateWithCompletionHandler:(void (^)(NCUpdateResult))completionHandler
called I will get the UIViewController and call the my get messages thread.
Linking the UIViewController against my widget target gave me an error:
'sharedApplication' is unavailable....
So I canceled it.
What I'm trying to achieve:
1. widgetPerformUpdateWithCompletionHandler is being called
2. Application start the get messages thread/method
3. when it finish, it send back data to the widget using NSUserDefaults
My code:
1:
- (void)widgetPerformUpdateWithCompletionHandler:(void (^)(NCUpdateResult))completionHandler
{
// Perform any setup necessary in order to update the view.
[self startGetMessages];
// If an error is encountered, use NCUpdateResultFailed
// If there's no update required, use NCUpdateResultNoData
// If there's an update, use NCUpdateResultNewData
completionHandler(NCUpdateResultNewData);
}
2:
- (void)startGetMessages
{
NSLog(#"%s", __PRETTY_FUNCTION__);
NSBundle *deviceBundle = [NSBundle mainBundle];
UIStoryboard *storyboard = [UIStoryboard storyboardWithName:#"Main" bundle:deviceBundle];
id MainController = [storyboard instantiateViewControllerWithIdentifier:#"MainTableViewController"];
SEL getMessagesSelector = NSSelectorFromString(#"startGetMessages:");
if (MainController)
{
NSThread *startGetMessagesThread = [[NSThread alloc] initWithTarget:MainController
selector:getMessagesSelector
object:StringForInt(HRTableDataSourceKindUpdate)];
[startGetMessagesThread start];
}
}
3:
- (void)notifyWidgetForChanges
{
__block NSMutableDictionary *newMessages = [NSMutableDictionary new];
NSArray *results = [CoreDataPhotoRecord MR_findAllSortedBy:#"message.originalDate"
ascending:NO
withPredicate:[NSPredicate predicateWithFormat:#"(message.delete_message == %#) AND (message.type.integerValue == %d) AND (message.originalDate >= %#)",
#NO, NORMAL_MESSAGE, _notiftWidgetDate]];
NSLog(#"%s, _notiftWidgetDate: %#, newMessages.count: %d", __PRETTY_FUNCTION__, _notiftWidgetDate, newMessages.count);
[results enumerateObjectsUsingBlock:^(CoreDataPhotoRecord *photoDetails, NSUInteger idx, BOOL *stop)
{
if (photoDetails != nil && photoDetails.message != nil)
{
NSString *cleanMobile = [[ABAddressBook sharedAddressBook] getCleanMobile:photoDetails.message.mobile];
Contact *person = [[ABAddressBook sharedAddressBook] findContactWithPhoneNumber:cleanMobile];
ContactWidget *contact = [[ContactWidget alloc] init];
contact.name = (person != nil && person.name != nil && person.name.length > 0) ? person.name : cleanMobile;
[newMessages setObject:contact forKey:cleanMobile];
}
}];
[SharedUtilities archiveObject:newMessages.copy forKey:MESSAGES_KEY_NEW widget:true];
[DEFAULTS_WIDGET setObject:#"111" forKey:#"111"];
[DEFAULTS_WIDGET synchronize];
newMessages = nil;
results = nil;
}
widgetDefaults = [[NSUserDefaults alloc] initWithSuiteName:WIDGET_GROUP_NAME];
Nothing is happen since the MainController in step 2 is nil.
What can I do?
The nil problem occurs because you try to access application's storyboard from widget. It's not straightforward, since the containing app and widget extension are being kept in a separate bundles. So the [NSBundle mainBundle] in step 2) is not the same bundle as the one in your app.
Possible solutions include:
including the app's Main.storyboard in extensions bundle either via adding it to Copy Bundle resources list at widget's target Build Phases tab or just adding widget target to Main.storyboard list of Target Membership
moving the code responsible for getting the messages from MainController startGetMessages: into a shared framework that will be accessible both from the app and the widget, preferably into a dedicated object.
The second one is way better. As a rule of thumb it's best to follow SOLID principles when doing the object-oriented programming, where S stands for single responsibility. It should not be a responsibility of view controller to provide the messages fetching system-wide. Creating a dedicated object that will have only one job - to get messages - and sharing it across the targets is a way to go.
Please consult the docs for the detailed explanation on how to create the shared framework: https://developer.apple.com/library/prerelease/ios/documentation/General/Conceptual/ExtensibilityPG/ExtensionScenarios.html#//apple_ref/doc/uid/TP40014214-CH21-SW1
I'm using Nico Kreipke's FTPManager (click here to go to GiHub) to download some data from an FTP address.
The code works if it's run before the user's first interaction, after that it will usually fail (about 9 out of 10).
When it fails, the following message is written (0x_ are actually valid addresses):
request (0x_) other than the current request(0x0) signalled it was complete on connection 0x_
That message isn't written by neither my code nor by FTPManager, but by Apple's. On its GitHub, I've found some one with the same error, but the source of it could possible be the same as mine. (That person wasn't using ARC.)
If I try to print the objects of those addresses with the pocommand, the console writes that there's no description available.
Also, the memory keeps adding up until the app receives a memory warning, and soon after the OS terminates it.
By pausing the app when that message appears, I can see that the main thread is in a run loop.
CFRunLoopRun();
The Code
self.ftpManager = [[FTPManager alloc] init];
[self downloadFTPFiles:#"192.168.2.1/sda1/1668"];
ftpManageris a strong reference.
The downloadFTPFiles: method:
- (void) downloadFTPFiles:(NSString*) basePath
{
NSLog(#"Reading contents of path: %#", basePath);
FMServer* server = [FMServer serverWithDestination: basePath username:#"test" password:#"test"];
NSArray* serverData = [self.ftpManager contentsOfServer:server];
NSLog(#"Number of items: %d", serverData.count);
for(int i=0; i < serverData.count; i++)
{
NSDictionary * sDataI = serverData[i];
NSString* name = [sDataI objectForKey:(id)kCFFTPResourceName];
NSNumber* type = [sDataI objectForKey:(id)kCFFTPResourceType];
if([type intValue] == 4)
{
NSLog(#"%# is Folder", name);
NSString * nextDestination = [basePath stringByAppendingPathComponent: name];
[self downloadFTPFiles:nextDestination];
}
else
{
NSLog(#"%# is File", name);
[self.ftpManager downloadFile:name toDirectory:[NSURL fileURLWithPath:NSHomeDirectory()] fromServer:server];
}
}
}
What I've Done
I've tried running that code on several places:
The app delegate's application:didFinishLaunchingWithOptions:;
The viewDidLoad, viewWillAppear: and viewDidAppear: of the a view controller loaded just after the app launches and a view controller presented later.
By an action triggered with a button event.
The download of the data is always well performed when executed by the delegate or a view controller loaded with the app (with an exception). But when run after the user's first interaction with the app, it'll most likely fail with the mentioned error.
The exception for view controllers loaded before the user's first interaction is when the call is in either the viewWillAppear: or viewDidAppear: methods. When it's called a second time (for example, a tab of a tab bar controller) it'll also, most likely, fail.
The Question
Does anyone have an idea of what may be happening, or if I'm doing something wrong? Or any alternative solution, maybe?
Any help to solve this problem will be welcomed.
Thanks,
Tiago
I ended up sending the downloadFile:toDirectory:fromServer: message inside a dispatch_async block. I've also created an FTPManage for every file downloaded.
It worked, but I have no idea why.
I'm leaving this answer to whomever crosses with this problem.
If anyone can let me know why this technique worked, please comment bellow so I can update the answer.
Here's the new way I'm downloading each file:
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
FTPManager *manager = [[FTPManager alloc] init];
[manager downloadFile:name toDirectory:[NSURL fileURLWithPath:path] fromServer:server];
});
Again, If you know why this worked, let me know.
Thanks.
Full Method
- (void) downloadFTPFiles:(NSString*) basePath
{
NSLog(#"Reading contents of path: %#", basePath);
FMServer *server = [FMServer serverWithDestination:basePath username:#"test" password:#"test"];
NSArray *serverData = [self.ftpManager contentsOfServer:server];
NSLog(#"Number of items: %d", serverData.count);
for(int i=0; i < serverData.count; i++)
{
NSDictionary *sDataI = serverData[i];
NSString *name = [sDataI objectForKey:(id)kCFFTPResourceName];
NSNumber *type = [sDataI objectForKey:(id)kCFFTPResourceType];
if([type intValue] == 4)
{
NSLog(#"%# is Folder", name);
NSString *nextDestination = [basePath stringByAppendingPathComponent:name];
[self downloadFTPFiles:nextDestination];
}
else
{
NSLog(#"%# is File", name);
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
FTPManager *manager = [[FTPManager alloc] init];
[manager downloadFile:name toDirectory:[NSURL fileURLWithPath:path] fromServer:server];
});
}
}
}
Is there any way to capture the event occurs when a user connects to a particular WiFi network in iOS app. It is fine even if this can be achieved using any private library which doesn't require super user privileges (jail break). I just want to capture the changing event of the connected SSID.
I would recommend simply using what Larme posted, and setting up an NSTimer to check every second or so, what the SSID of your current network is, if you detect a change, simply do whatever you need to do. Keep in mind, changing WiFi networks is not something that happens instantaneously, so having a 1 second resolution is not bad
In applicationDidFinishLoading
NSTimer *ssidTimer = [NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:#selector(fetchSSIDInfo) userInfo:nil repeats:YES];
In AppDelegate
- (id)fetchSSIDInfo {
NSArray *ifs = (__bridge_transfer id)CNCopySupportedInterfaces();
NSLog(#"Supported interfaces: %#", ifs);
id info = nil;
NSString *ifnam = #"";
for (ifnam in ifs) {
info = (__bridge_transfer id)CNCopyCurrentNetworkInfo((__bridge CFStringRef)ifnam);
NSLog(#"%# => %#", ifnam, info);
if (info && [info count]) { break; }
}
if ([info count] >= 1 && [ifnam caseInsensitiveCompare:prevSSID] != NSOrderedSame) {
// Trigger some event
prevSSID = ifnam;
}
return info;
}
Something like that. I can not check if code is typo free as I am not in front of a mac, but it should not be too different
You can fetch details from your wifi connection:
- (NSDictionary *)getConnectionDetails
{
NSDictionary *connectionDetails = [NSDictionary dictionary];
CFArrayRef myArray = CNCopySupportedInterfaces();
if (myArray) {
CFDictionaryRef myDict = CNCopyCurrentNetworkInfo(CFArrayGetValueAtIndex(myArray, 0));
connectionDetails = (__bridge_transfer NSDictionary*)myDict;
}
return connectionDetails;
}
And then if check [connectionDetails valueForKey:#"BSSID"] you will get BSSID.
Also please note that you must to import #import <SystemConfiguration/CaptiveNetwork.h>
You want SystemConfiguration, which has facilities for seeing notifications on all sorts of networking changes. In particular you'll want to use SCDynamicStoreSetNotificationKeys to listen for changes to the devices and SCNetworkConfiguration to get information about the available interfaces.
I'm new to ios development.My app gets slower when i'm parsing image using json parser in ios 5.
Please could anybody help to solve this problem.
-(NSDictionary *)Getdata
{
NSString *urlString = [NSString stringWithFormat:#"url link"];
urlString = [urlString stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceAndNewlineCharacterSet]];
NSURL *url = [NSURL URLWithString:urlString];
NSData* data = [NSData dataWithContentsOfURL:url];
NSError* error;
NSDictionary* json;
if (data) {
json = [NSJSONSerialization JSONObjectWithData:data options:kNilOptions error:&error];
NSLog(#"json...%#",json);
}
if (error) {
NSLog(#"error is %#", [error localizedDescription]);
// Handle Error and return
// return;
}
return json;
}
Your description of the problem isn't exactly helpful. It's unclear to me if everything in your app is slow, or just certain operations; if you exprience a slow action and then it becomes fast again or if it continues to perform slowly.
Whatever, the general rule is to performan all network communication including the parsing of the answer on a separate thread, i.e. not on the main thread that is responsible for managing the user interface. That way the app remains responsive and appears to be fast.
If you can download the images separately, you can already display the result and put a placeholder where the image will appear. Later, when you have received the image you remove the placeholder and put the image there.
This line is probably the culprit.
NSData* data = [NSData dataWithContentsOfURL:url];
If you're calling this on the main thread (and because you haven't mentioned threads at all I suspect that you are) it will block everything and wait until the server has responded.
This is a spectacularly bad experience for the user :)
You need to do all of this on a background thread and notify the main thread when you're done. There's a couple of ways of doing this (NSOperation etc) but the simplest is just this :
// Instead of calling 'GetData', do this instead
[self performSelectorOnBackgroundThread:#selector(GetData) withObject:nil];
// You can't return anything from this because it's going to be run in the background
-(void)GetData {
...
...
// Instead of 'return json', you need to pass it back to the main thread
[self performSelectorOnMainThread:#selector(GotData:) withObject:json waitUntilDone:NO];
}
// This gets run on the main thread with the JSON that's been got and parsed in the background
- (void)GotData:(NSDictionary *)json {
// I don't know what you were doing with your JSON but you should do it here :)
}