I'm trying to add a QLPreviewController's view as a subview (no--I cannot use a nav controller or modal). It only shows the fabric background of the QLPreviewController.
I create one and add it as a subview:
QLPreviewController* preview = [[[QLPreviewController alloc] init] autorelease];
preview.dataSource = self;
preview.delegate = self;
preview.view.frame = CGRectMake(0, 0, self.pdfPreviewView.frame.size.width, self.pdfPreviewView.frame.size.height);
self.pdfPreviewView.previewController = preview;
[self.pdfPreviewView addSubview:preview.view];
[preview reloadData];
My QLPreviewControllerDataSource methods work fine (viewing 1 pdf at a time):
- (id <QLPreviewItem>) previewController: (QLPreviewController *) controller previewItemAtIndex: (NSInteger) index
{
NSString *path = [[ResourceManager defaultManager] pathForPDF:self.currentPDF];
NSURL *url = [NSURL fileURLWithPath:path];
if ([QLPreviewController canPreviewItem:url]) {
return url; // This always returns
}
return nil; // This line is never executed
}
- (NSInteger)numberOfPreviewItemsInPreviewController:(QLPreviewController *)controller
{
return 1;
}
The data source method always returns the file url, and QLPreviewController says it can open the file, but it never actually does. I just get the background. The self.currentPDF is set before I create the QLPreviewController and does contain the correct information (from CoreData).
The delegate methods never get called. But I'm also not using it in a standard way, so that's not totally unexpected.
I've also tried calling [preview setNeedsLayout], [preview setNeedsDisplay'], and [preview refreshCurrentPreviewItem] but those just call the data source methods and don't change anything.
The PDFs are valid. I can open them in both Xcode and Preview, so that's not the problem. I'm kind of stumped as to why this won't work. Any help would be appreciated in getting this to work.
Turns out I was sending QLPreviewController the wrong path. It wasn't finding the PDF in the bundle correctly. I needed to use pathForResource:ofType:inDirectory.
Related
While using NSURLSession to download files and display them in UICollectionView I found a problem where cells do not update correctly from NSOperationQueue block. Download part and file store works correctly every time. But update cell progress or images works only on initial load of controller. If I navigate to root and then again to my Collection controller download works but cells no longer update. I found this interesting discussion but it did not help in my case.
More details, the controller that starts URL session and handles tasks gets loaded from storyboard segue. I noticed app is creating new controller instance every time. On 2nd navigation visit cells do not show progress or update but task/files are download correctly. It seem that my download tasks are getting copy of cells from some other controller instance. But it does not make sense from what I see in debugger, delegates are working correctly, task completes with success.
Here is code method that fail to update cells on 2nd visit to controller:
-(void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask didWriteData:(int64_t)bytesWritten totalBytesWritten:(int64_t)totalBytesWritten totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite{
if (totalBytesExpectedToWrite == NSURLSessionTransferSizeUnknown) {
NSLog(#"Unknown transfer size");
}
else{
// Locate the FileDownloadInfo object in array based on my unique key in URL.
int index = [self getFileDownloadInfoIndexWithTaskURL:downloadTask.originalRequest.URL.lastPathComponent];
// Get singleton download object list from app delegate
NSMutableArray *globalFileDownloadData = [self getGlobalDownloadFileList];
FileDownloadInfo *fdi = [globalFileDownloadData objectAtIndex:index];
// Get the progress view of the appropriate cell and update its progress.
NSArray *arr = [self.fileDispCollection visibleCells];
for(FileItemCell* cell in arr){
if ([fdi.contentId isEqualToString:cell.testLbl.text]){
[[NSOperationQueue mainQueue] addOperationWithBlock:^{
// This code works when app start initial visit to controller
// but does not work on2nd 3rd or other revisit
// even cells found correctly, files also loaded saved
// the progress does not show and no update
cell.downloadProgress.hidden = NO;
cell.downloadProgress.progress = fdi.downloadProgress;
}];
}
}
}
}
I initialize my singleton session using this method:
- (NSURLSession *)backgroundSession {
//disptach_once ensure that multiple background sessions are not
//created in this instance of the application.
static NSURLSession *session = nil;
static dispatch_once_t onceToken;
NSArray *URLs = [[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask];
self.docDirectoryURL = [URLs objectAtIndex:0];
dispatch_once(&onceToken, ^{
NSURLSessionConfiguration *sessionConfiguration = [NSURLSessionConfiguration backgroundSessionConfigurationWithIdentifier:#"com.Transport.demo"];
sessionConfiguration.HTTPMaximumConnectionsPerHost = 3;
sessionConfiguration.discretionary = NO;
session = [NSURLSession sessionWithConfiguration:sessionConfiguration
delegate:self
delegateQueue:nil];
});
return session;
}
What can cause a 2nd copy of cells or simply collection cell not to respond to calls or data reload on 2nd navigation round? Hope somebody have a solution for this problem.
try to put you update UI code in the main thread like this:
dispatch_async(dispatch_get_main_queue(), ^{
//your update UI code
});
The answer turned out in my question. The storyboard segue was creating new controller that was creator and handler for URLSession download tasks. Session was singleton that kept initial controller stack and delegate. So new controller instance will start downloads but all responses will go to old controller instance.
Fix was simple not use performSegueWithIdentifier, instead create single controller instance, in this case is actually better solution.
if (!self.library){
UIStoryboard *storyboard = [UIStoryboard storyboardWithName:#"MainStoryboard" bundle: nil];
self.library = [storyboard instantiateViewControllerWithIdentifier:#"libraryScene"];
}
self.library.model = self.selectNode;
[self.navigationController pushViewController:self.library animated:YES];
I'm trying to write a simple (toy) program that uses the NSFilePresenter and NSFileCoordinator methods to watch a file for changes.
The program consists of a text view that loads a (hardcoded) text file and a button that will save the file with any changes. The idea is that I have two instances running and saving in one instance will cause the other instance to reload the changed file.
Loading and saving the file works fine but the NSFilePresenter methods are never called. It is all based around a class called FileManager which implements the NSFilePresenter protocol. The code is as follows:
Interface:
#interface FileManager : NSObject <NSFilePresenter>
#property (unsafe_unretained) IBOutlet NSTextView *textView;
- (void) saveFile;
- (void) reloadFile;
#end
Implementation:
#implementation FileManager
{
NSOperationQueue* queue;
NSURL* fileURL;
}
- (id) init {
self = [super init];
if (self) {
self->queue = [NSOperationQueue new];
self->fileURL = [NSURL URLWithString:#"/Users/Jonathan/file.txt"];
[NSFileCoordinator addFilePresenter:self];
}
return self;
}
- (NSURL*) presentedItemURL {
NSLog(#"presentedItemURL");
return self->fileURL;
}
- (NSOperationQueue*) presentedItemOperationQueue {
NSLog(#"presentedItemOperationQueue");
return self->queue;
}
- (void) saveFile {
NSFileCoordinator* coordinator = [[NSFileCoordinator alloc] initWithFilePresenter:self];
NSError* error;
[coordinator coordinateWritingItemAtURL:self->fileURL options:NSFileCoordinatorWritingForMerging error:&error byAccessor:^(NSURL* url) {
NSString* content = [self.textView string];
[content writeToFile:[url path] atomically:YES encoding:NSUTF8StringEncoding error:NULL];
}];
}
- (void) reloadFile {
NSFileManager* fileManager = [NSFileManager defaultManager];
NSFileCoordinator* coordinator = [[NSFileCoordinator alloc] initWithFilePresenter:self];
NSError* error;
__block NSData* content;
[coordinator coordinateReadingItemAtURL:self->fileURL options:0 error:&error byAccessor:^(NSURL* url) {
if ([fileManager fileExistsAtPath:[url path]]) {
content = [fileManager contentsAtPath:[url path]];
}
}];
dispatch_async(dispatch_get_main_queue(), ^{
[self.textView setString:[[NSString alloc] initWithData:content encoding:NSUTF8StringEncoding]];
});
}
// After this I implement *every* method in the NSFilePresenter protocol. Each one
// simply logs its method name (so I can see it has been called) and calls reloadFile
// (not the correct implementation for all of them I know, but good enough for now).
#end
Note, reloadFile is called in applicationDidFinishLaunching and saveFile gets called every time the save button is click (via the app delegate).
The only NSFilePresenter method that ever gets called (going by the logs) is presentedItemURL (which gets called four times when the program starts and loads the file and three times whenever save is clicked. Clicking save in a second instance has no noticeable effect on the first instance.
Can anyone tell me what I'm doing wrong here?
I was struggling with this exact issue for quite a while. For me, the only method that would be called was -presentedSubitemDidChangeAtURL: (I was monitoring a directory rather than a file). I opened a technical support issue with Apple, and their response was that this is a bug, and the only thing we can do right now is to do everything through -presentedSubitemDidChangeAtURL: if you're monitoring a directory. Not sure what can be done when monitoring a file.
I would encourage anyone encountering this issue to file a bug (https://bugreport.apple.com) to encourage Apple to get this problem fixed as soon as possible.
(I realize that this is an old question, but... :) )
First of all, I notice you don't have [NSFileCoordinator removeFilePresenter:self]; anywhere (it should be in dealloc).
Secondly, you wrote:
// After this I implement *every* method in the NSFilePresenter protocol. Each one
// simply logs its method name (so I can see it has been called) and calls reloadFile
// (not the correct implementation for all of them I know, but good enough for now).
You're right: it's the incorrect implementation! And you're wrong: it's not good enough, because it's essential for methods like accommodatePresentedItemDeletionWithCompletionHandler: which take a completion block as a parameter, that you actually call this completion block whenever you implement them, e.g.
- (void) savePresentedItemChangesWithCompletionHandler:(void (^)(NSError * _Nullable))completionHandler
{
// implement your save routine here, but only if you need to!
if ( dataHasChanged ) [self save]; // <-- meta code
//
NSError * err = nil; // <-- = no error, in this simple implementation
completionHandler(err); // <-- essential!
}
I don't know whether this is the reason your protocol methods are not being called, but it's certainly a place to start. Well, assuming you haven't already worked out what was wrong in the past three years! :-)
In iOS 6 the QLPreviewController no longer loads a PDF from a URL. It works fine in iOS 5. I have implemented the QLPreviewControllerDataSource methods as documented here.
#pragma mark - QLPreviewControllerDataSource
- (NSInteger)numberOfPreviewItemsInPreviewController:(QLPreviewController *)controller {
return 1;
}
- (id <QLPreviewItem>) previewController: (QLPreviewController *) controller previewItemAtIndex: (NSInteger) index;
{
NSURL *fileURL = [NSURL URLWithString:#"http://www.bliley.net/XTAL/PDF_Instructions/Test_File.pdf"];
return fileURL;
}
This works perfectly in iOS 5, however in iOS 6 the console outputs:
Couldn't issue file extension for path: /XTAL/PDF_Instructions/Test_File.pdf
Have you tried using fileURLWithPath instead of URLWithString? I had other issues that were fixed by doing so.
Also not sure if QLPreviewController will handle remote URLs. If not, you could download the file and then display it.
I downloaded the file from remote url and saved locally, then I display the PDF using the QLPreviewController .In iOS 6 its working.
First i saved the file from remote url using the following code :
NSString *local_location;
NSString *path = [[NSBundle mainBundle] pathForResource:#"sampleData" ofType:#"plist"];
path = NSTemporaryDirectory();
local_location= [path stringByAppendingPathComponent:[NSString stringWithFormat:#"My_Invoice.pdf"]];
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:[NSURL URLWithString: remoteurl]];
[request setDownloadDestinationPath:local_location];
[request startSynchronous];
For showing the Pdf :
QLPreviewController* preview = [[QLPreviewController alloc] init];
preview.dataSource = self;
[self presentModalViewController:preview animated:YES];
QLPreviewController delegate methods are :
- (NSInteger) numberOfPreviewItemsInPreviewController: (QLPreviewController *) controller
{
return 1;
}
- (id <QLPreviewItem>)previewController:(QLPreviewController *)controller previewItemAtIndex:(NSInteger)index
{
return [NSURL fileURLWithPath:local_location];
}
I am having a similar issue and seems like it might stem from a stricter enforcement of the file-type URL of QLPreviewItem
#property (readonly) NSURL *previewItemURL;
Discussion
This property is used by a Quick Look preview controller to get an item’s URL. In typical use, you would implement a getter method in your preview item class to provide this value.
The value of this property must be a file-type URL.
If the item is not available for preview, this property’s getter method should return nil. In this case, the Quick Look preview controller displays a “loading” view.
Availability
Available in iOS 4.0 and later.
Declared In
QLPreviewItem.h
UPDATE: I have opened a bug with Apple dealing with this issue for iOS 6 and it seems they have aced it as a bug so may offer a fix in the near future. The bug I opened had to do with using custom NSURLProtocols for the preview, but may apply to other aspects as well.
Link to class
But note that QLPreviewController expects a URL to a local resource
You would need to download and save the PDF file locally first and then create a proper file URL to the local file.
I m passing an url as string from UIviewController to another uiviewcontroller..i was able to pass the url successfully but not able to load the string in the webview...in console i m getting a null value in webview could u guys help me out below is the code...
-(void)playAction1
{
webviewcontroller *newEnterNameController = [[webviewcontroller alloc] initWithItem:#"http://www.theappcodeblog.com/?p=222"];
[self.navigationController pushViewController:newEnterNameController animated:YES];
[newEnterNameController release];
}
- (id)initWithItem:(NSString *)url
{
if (self = [super initWithNibName:#"webviewcontroller" bundle:nil])
{
self.title=#"facebook";
self.url1 = [NSURL URLWithString:url];
//URL Requst Object
self.requestObj1 = [NSURLRequest requestWithURL:url1];
NSURLConnection *connection=[[[NSURLConnection alloc] initWithRequest:self.requestObj1 delegate:self]autorelease];
[self.webViewAnnouncements loadRequest:self.requestObj1];
NSLog(#"webView:%#",webViewAnnouncements);
[self.webViewAnnouncements setDelegate:self];
}
return self;
}
While what you're doing doesn't look wrong to me (in truth I'd need to see .h and .xib files) as well to be sure. I would consider the initWithItem to be an unusual pattern.
If I was you, I would init the view controller in the "normal" way using initWithNib and then create the URL as a property type and set it before you present the view controller to the screen.
I have hit the proverbial wall trying to figure out how to populate an NSImage with data returned from an asynchronous NSURLConnection in my desktop app (NOT an iPhone application!!).
Here is the situation.
I have a table that is using custom cells. In each custom cell is an NSImage which is being pulled from a web server. In order to populate the image I can do a synchronous request easily:
myThumbnail = [[NSImage alloc] initWithContentsOfFile:myFilePath];
The problem with this is that the table blocks until the images are populated (obviously because it's a synchronous request). On a big table this makes scrolling unbearable, but even just populating the images on the first run can be tedious if they are of any significant size.
So I create an asynchronous request class that will retrieve the data in its own thread as per Apple's documentation. No problem there. I can see the data being pulled and populated (via my log files).
The problem I have is once I have the data, I need a callback into my calling class (the custom table view).
I was under the impression that I could do something like this, but it doesn't work because (I'm assuming) that what my calling class really needs is a delegate:
NSImage * myIMage;
myImage = [myConnectionClass getMyImageMethod];
In my connection class delegate I can see I get the data, I just don't see how to pass it back to the calling class. My connectionDidFinishLoading method is straight from the Apple docs:
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
// do something with the data
// receivedData is declared as a method instance elsewhere
NSLog(#"Succeeded! Received %d bytes of data",[receivedData length]);
// release the connection, and the data object
[connection release];
[receivedData release];
}
I am hoping this is a simple problem to solve, but I fear I am at the limit of my knowledge on this one and despite some serious Google searches and trying many different recommended approaches I am struggling to come up with a solution.
Eventually I will have a sophisticated caching mechanism for my app in which the table view checks the local machine for the images before going out and getting them form the server and maybe has a progress indicator until the images are retrieved. Right now even local image population can be sluggish if the image's are large enough using a synchronous process.
Any and all help would be very much appreciated.
Solution Update
In case anyone else needs a similar solution thanks to Ben's help here is what I came up with (generically modified for posting of course). Bear in mind that I have also implemented a custom caching of images and have made my image loading class generic enough to be used by various places in my app for calling images.
In my calling method, which in my case was a custom cell within a table...
ImageLoaderClass * myLoader = [[[ImageLoaderClass alloc] init] autorelease];
[myLoader fetchImageWithURL:#"/my/thumbnail/path/with/filename.png"
forMethod:#"myUniqueRef"
withId:1234
saveToCache:YES
cachePath:#"/path/to/my/custom/cache"];
This creates an instance of myLoader class and passes it 4 parameters. The URL of the image I want to get, a unique reference that I use to determine which class made the call when setting up the notification observers, the ID of the image, whether I want to save the image to cache or not and the path to the cache.
My ImageLoaderClass defines the method called above where I set what is passed from the calling cell:
-(void)fetchImageWithURL:(NSString *)imageURL
forMethod:(NSString *)methodPassed
withId:(int)imageIdPassed
saveToCache:(BOOL)shouldISaveThis
cachePath:(NSString *)cachePathToUse
{
NSURLRequest *theRequest=[NSURLRequest requestWithURL:[NSURL URLWithString:imageURL]
cachePolicy:NSURLRequestUseProtocolCachePolicy
timeoutInterval:60.0];
// Create the connection with the request and start loading the data
NSURLConnection *theConnection=[[NSURLConnection alloc] initWithRequest:theRequest delegate:self];
if (theConnection) {
// Create the NSMutableData that will hold
// the received data
// receivedData is declared as a method instance elsewhere
receivedData = [[NSMutableData data] retain];
// Now set the variables from the calling class
[self setCallingMethod:methodPassed];
[self setImageId:imageIdPassed];
[self setSaveImage:shouldISaveThis];
[self setImageCachePath:cachePathToUse];
} else {
// Do something to tell the user the image could not be downloaded
}
}
In the connectionDidFinishLoading method I saved the file to cache if needed and made a notification call to any listening observers:
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
NSLog(#"Succeeded! Received %d bytes of data",[receivedData length]);
// Create an image representation to use if not saving to cache
// And create a dictionary to send with the notification
NSImage * mImage = [[NSImage alloc ] initWithData:receivedData];
NSMutableDictionary * mDict = [[NSMutableDictionary alloc] init];
// Add the ID into the dictionary so we can reference it if needed
[mDict setObject:[NSNumber numberWithInteger:imageId] forKey:#"imageId"];
if (saveImage)
{
// We just need to add the image to the dictionary and return it
// because we aren't saving it to the custom cache
// Put the mutable data into NSData so we can write it out
NSData * dataToSave = [[NSData alloc] initWithData:receivedData];
if (![dataToSave writeToFile:imageCachePath atomically:NO])
NSLog(#"An error occured writing out the file");
}
else
{
// Save the image to the custom cache
[mDict setObject:mImage forKey:#"image"];
}
// Now send the notification with the dictionary
NSNotificationCenter *nc = [NSNotificationCenter defaultCenter];
[nc postNotificationName:callingMethod object:self userInfo:mDict];
// And do some memory management cleanup
[mImage release];
[mDict release];
[connection release];
[receivedData release];
}
Finally in the table controller set up an observer to listen for the notification and send it off to the method to handle re-displaying the custom cell:
-(id)init
{
[super init];
NSNotificationCenter *nc = [NSNotificationCenter defaultCenter];
[nc addObserver:self selector:#selector(updateCellData:) name:#"myUniqueRef" object:nil];
return self;
}
Problem solved!
My solution is to use Grand Central Dispatch (GCD) for this purpose, you could save the image to disc too in the line after you got it from the server.
- (NSView *)tableView:(NSTableView *)_tableView viewForTableColumn:(NSTableColumn *)tableColumn row:(NSInteger)row
{
SomeItem *item = [self.items objectAtIndex:row];
NSTableCellView *cell = [_tableView makeViewWithIdentifier:tableColumn.identifier owner:self];
if (item.artworkUrl)
{
cell.imageView.image = nil;
dispatch_async(dispatch_queue_create("getAsynchronIconsGDQueue", NULL),
^{
NSURL *url = [NSURL URLWithString:item.artworkUrl];
NSImage *image = [[NSImage alloc] initWithContentsOfURL:url];
cell.imageView.image = image;
});
}
else
{
cell.imageView.image = nil;
}
return cell;
}
(I am using Automatic Reference Counting (ARC) therefore there are no retain and release.)
Your intuition is correct; you want to have a callback from the object which is the NSURLConnection’s delegate to the controller which manages the table view, which would update your data source and then call -setNeedsDisplayInRect: with the rect of the row to which the image corresponds.
Have you tried using the initWithContentsOfURL: method?