I'm running into a problem that I'm not sure how to solve. Let me just give some relevant code.
FrontpageViewController (viewDidLoad)
NewsFetcher *newsFetcher = [[NewsFetcher alloc] initWithURL:url];
newsFetcher.delegate = self;
[newsFetcher loadData];
NewsFetcher.h
#property (nonatomic, unsafe_unretained) id <NewsFetcherDelegate> delegate;
I'm using unsafe_unretained because I want my app to work with iOS 4 as well, while still using ARC for convenience.
NewsFetcher.m
- (id)initWithURL:(NSURL *)url {
self = [super init];
if (self) {
self.url = url;
self.receivedData = [[NSData alloc] init];
}
return self;
}
- (void)loadData {
NSLog(#"%#", self.delegate); // FrontpageViewController, as expected
NSURLRequest *request = [NSURLRequest requestWithURL:self.url
cachePolicy:NSURLRequestReloadIgnoringCacheData
timeoutInterval:15];
if (self.connectionInProgress)
[self.connectionInProgress cancel];
self.connectionInProgress = [[NSURLConnection alloc] initWithRequest:request
delegate:self
startImmediately:YES];
}
This all works fine. NewsFetcher conforms to the NSURLConnectionDelegate protocol, so the next method that's being called is connection:didReceiveData:. However, when I do another NSLog(#"%#", self.delegate) within that method, I get varied results (EXEC_BAD_ACCESS, NSCFDictionary, etc.). I think this means that my delegate property points to a released object, which is weird because it's supposed to be the view controller that's still on screen (and therefore couldn't have been released, right?).
How is my delegate available in one method, but not anymore in the next method? Does it have to do with the unsafe_unretained?
Delegate objects are not retained (by convention) by callers. The expectation is that the caller who set it on your object will retain it. Recommend you use the Instruments tool with zombies (and then with leaks) to see what's going on.
Related
I have 2 classes as NSObject subclasses:
1st class is more likely act as adapter. It send data to Class2 for process async task. When delegaton fired I would like to post back data to adaptor class.
In adaptor class:
Class2 *cls = [[Class2 alloc] init];
[ftc fetchLocation];
In Class2.m
-(void)fetchLocation{
if(IS_OS_8_OR_LATER) {
[self.locationManager requestAlwaysAuthorization];
}
self.locationManager = [[CLLocationManager alloc] init];
if ([CLLocationManager locationServicesEnabled]){
NSLog(#"Enable");
}
self.locationManager.delegate =self;
self.locationManager.desiredAccuracy = kCLLocationAccuracyBest;
[self.locationManager requestWhenInUseAuthorization];
[self.locationManager requestAlwaysAuthorization];
[self.locationManager startUpdatingLocation];
}
When I call fetch-location method from adaptor, it really calls and reads lines, but after that, Class2 disappears and gone back to Adapter class without waiting delegation (didUpdateLocations)
-(void)locationManager:(CLLocationManager *)manager didUpdateLocations:(NSArray *)locations{
NSString *latitude = [NSString stringWithFormat:#"%f",self.locationManager.location.coordinate.latitude];
NSString *longtitude = [NSString stringWithFormat:#"%f",self.locationManager.location.coordinate.longitude];
NSString *altitude = [NSString stringWithFormat:#"%f",self.locationManager.location.altitude];
NSString *speed = [NSString stringWithFormat:#"%f",self.locationManager.location.speed];
NSDictionary *locationDictionary = #{#"latitude":latitude,#"longtitude":longtitude,#"altitude":altitude,#"speed":speed};
if (locations.count >0 && [locations isKindOfClass:[NSArray class]]) {
[self.delegate userLocationHasUpdated:self :locationDictionary];
[self.locationManager stopUpdatingLocation];
self.locationManager = nil;
return;
}
}
But if I just run Class2 and remove adapter from compile (with first initialiser) it runs as expected, How can I achieve to handle delegation methods from another class that fired ?
Best Regards.
You have several options, really. One could be making your second class a property of your first class (singleton pattern would fit nice here, I guess). Then you can either declare a protocol in your second class and notify your first class via delegate methods (non-singleton implementation) or use NSNotificationCenter to post a notification (singleton implementation).
The second option would be to pass a block with completion handler to the second class. You could declare your method in the second class like this, for example (adjust return type and arguments of the block, if needed):
- (void)updateLocationWithCompletionHandler:(void (^)(void))completion;
Implement it so that you call the completion block after you get the geolocation update results.
And call it from the first class like:
[self.secondClass updateLocationWithCompletionHandler:^
{
// Your completion code here.
}];
Hope this helps (sorry, didn't check the code in Xcode, get rid of typos, if any).
Possible duplicate of iOS CLLocationManager in a separate class. You have to create a singleton class for to get the location if you want to have seperate class for handing the location manager. You will find the guidance from the shared link
REVISED...
The crux of the app is communicating with a database server. Responses from the server to the app are all in XML. There are several screens. Example, screen 1 lists the user's information, screen 2 lists the user's past trades, allows new trades, and so on.
Here is some code from my AppDelegate:
StartViewController *svc = [[StartViewController alloc] init];
TradeViewController *tvc = [[TradeViewController alloc] init];
CashViewController *cvc = [[CashViewController alloc] init];
ComViewController *covc = [[ComViewController alloc] init];
PrefsViewController *pvc = [[PrefsViewController alloc] init];
NSMutableArray *tabBarViewControllers = [[NSMutableArray alloc] initWithCapacity:5];
UITabBarController *tabBarController = [[UITabBarController alloc] init];
UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:svc];
[tabBarViewControllers addObject:navigationController];
navigationController = nil;
navigationController = [[UINavigationController alloc] initWithRootViewController:tvc];
[tabBarViewControllers addObject:navigationController];
navigationController = nil;
navigationController = [[UINavigationController alloc] initWithRootViewController:cvc];
[tabBarViewControllers addObject:navigationController];
navigationController = nil;
navigationController = [[UINavigationController alloc] initWithRootViewController:covc];
[tabBarViewControllers addObject:navigationController];
navigationController = nil;
navigationController = [[UINavigationController alloc] initWithRootViewController:pvc];
[tabBarViewControllers addObject:navigationController];
navigationController = nil;
[tabBarController setViewControllers:tabBarViewControllers];
[[self window] setRootViewController:tabBarController];
self.window.backgroundColor = [UIColor whiteColor];
[self.window makeKeyAndVisible];
Trying to stick with the MVC style, I have a singleton class which does all of the "processing".
Now an example on how I run into a wall… the user can change their email address on screen 5. Enter new email address into text field and click the save button. The button then calls a method from the singleton class which sends the new email address to the server and (via the URL) and receives a XML response confirming the change.
Here are my problems:
1. I start the spinner from the view controller before I make the singleton class method call - but not knowing when the app to server send/receive is finished, how do I make the spinner stop at the right time? I can't of it from the singleton class, I tried that. From what I know, it has to be from within the VC or is there a way to change VC output from my singleton class?
The singleton class NSURLConnection is handling ALL of my communication. Everything from a simple, email change all the way to updating transaction tables. This just seems wrong to me and makes it very difficult to keep track on who is calling what. Again, I am going by my interpretation of MVC. I think it would be much easier to have a NSURLConnection for every VC and do some processing in those classes. However that would not be MVC(ish).
I have close to a 100 variables, arrays, etc… in my singleton class which I use to assign values to all my VC. This also seems wrong to me but I can't think of any other way.
how can I distinguish in the NSURLConnection delegate
(connectionDidFinishLoading) which URL call is being made?
Each of the delegate methods (such as -connectionDidFinishLoading:) has a connection parameter that tells you which connection sent the message. A given connection can only load one URL at a time, so there's a one to one correspondence between URLs and connections.
How can I tell outside of "connectionDidFinishLoading" when the download is completed?
That method tells you when the connection is finished. It's up to you to store that information somewhere where it's useful to your app.
Update: Based on what you've added, your "processing" class is your app's model. The rest of the app shouldn't care that each transaction involves a message to the server -- that's the model's business alone. Also, there's no reason that the model has to be a single object (let alone a singleton) -- it can be a group of objects that work together.
So, you might have a class (let's call it Processor) that represents the application's interface to the model (some might even call this a "model controller"). An instance of Processor might create a local database for storing the current local state of the app.You might also have a Transaction class that represents a single transaction with the server. A transaction could create a request, send it to the server, get the response, update the database, and tell the Processor that the transaction is done. Or, maybe when some other part of the app (like one of your view controllers) asks the Processor to process a new transaction, the Processor passes the requesting object along to the transaction that it creates so that the transaction can update the requestor directly.
It's hard to say what the best plan for your app is without knowing where you're planning on taking it, but the usual guidelines hold:
break your problem into parts that are easier to solve
limit the scope of each class's responsibilities
if something seems to complicated, it probably is
Breaking your model up into several classes will make it easier to test, as well. You can imagine how easy it would be to write a set of unit tests for the Transaction class. The same goes for Processor -- if the server transaction stuff is in a different class, it's easier to test that the Processor is doing the right thing.
If you have multiple NSURLConnections for the same delegate, consider using a global (well, let's say rather an instance variable) NSMutableDictionary instance, in which you store the data depending on which NSURLConnection is being called. You can use, for example, the in-memory address of the connections converted to an NSString (something like
[NSString stringWithFormat:#"%p", connection]
should do the trick).
Also, in the connectionDidFinishLoading: and connection:didFailLoadWithError: methods, remove the keys corresponding to the NSURLConnections. Thus, you can tell it from 'outside' if a connection is finished: just check if it is in the dictionary or not.
If you're downloading any data over a network connection, I would suggest using ASIHttpRequest. This will allow you to download files asynchronously, meaning your interface doesn't freeze during the download process.
If you use ASIHttpRequest, you can also set the didFinishSelector. By doing this, you can control which method is called when a specific URL has finished loading.
Have a look at this:
NSURL *url = [NSURL URLWithString:#"http://allseeing-i.com"];
ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];
[request setDelegate:self];
[request startAsynchronous];
[request setDidFinishSelector:#selector(requestDone:)];
Then:
- (void)requestDone:(ASIHTTPRequest *)request
{
// Use when fetching text data
NSString *responseString = [request responseString];
// Use when fetching binary data
NSData *responseData = [request responseData];
// If you want, you can get the url of the request like this
NSURL *url = [request url];
}
As for the second part of your question, if the requestDone: method has not been called, you know the download has not completed.
If you want to do something more complicated with multiple downloads, ASIHttpRequest offers queue functionality too. Take a look here.
Hope this will help you.
- (void)connectionDidFinishLoading:(NSURLConnection*)connection
{
NSString *urlString = [[[connection originalRequest] URL] absoluteString];
if ([urlString caseInsensitiveCompare:#"http://www.apple.com"] == NSOrderedSame) {
//Do Task#1
}
else if ([urlString caseInsensitiveCompare:#"http://www.google.com"] == NSOrderedSame)
{
//Do Task#2
}
}
I would recommend subclassing NSURLConnection. Simply add two properties: an NSInteger, tag, and a BOOL, isFinished. This way, you can #define tags for each different request and then identify them by tag in your delegate methods. In connectionDidFinishLoading, you can set the isFinished BOOL to YES, and then you can check in other methods if then connection is finished.
Here's my own NSURLConnection subclass, TTURLConnection:
TTURLConnection.h:
#import <Foundation/Foundation.h>
#interface TTURLConnection : NSURLConnection <NSURLConnectionDelegate>
#property (nonatomic) NSInteger tag;
#property (nonatomic) BOOL isLocked;
- (id)initWithRequest:(NSURLRequest *)request delegate:(id)delegate startImmediately:
(BOOL)startImmediately tag:(NSInteger)tagParam;
#end
TTURLConnection.m:
#import "TTURLConnection.h"
#implementation TTURLConnection
#synthesize tag;
- (id)initWithRequest:(NSURLRequest *)request delegate:(id)delegate startImmediately:
(BOOL)startImmediately tag:(NSInteger)tagParam {
self = [super initWithRequest:request delegate:delegate
startImmediately:startImmediately];
if(self) {
self.tag = tagParam;
}
return self;
}
#end
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.
Hey all, I'm trying to use Yahoo's PlaceFinder to do reverse geocoding for an app I'm making. Problem is I need to use the NSURLConnection to call to my database. So I decided to make a custom class that is initialized with the user's latitude and longitude, and only store a string variable containing the state the user is in.
Update the following code now works fine....
Here is the .h
#import <Foundation/Foundation.h>
#import "CJSONDeserializer.h"
#interface StateFinder : NSObject
{
NSString *userState;
NSURLConnection *connection;
}
-(id)initwithLatitude:(NSString *)latitude andLongitude:(NSString *)longitude;
#property (nonatomic, retain) NSString *userState;
#property (nonatomic, retain) NSURLConnection *connection;
#end
and the .m
#import "StateFinder.h"
#implementation StateFinder
#synthesize userState;
#synthesize connection;
-(id)initwithLatitude:(NSString *)latitude andLongitude:(NSString *)longitude
{
if(self = [super init])
{
NSString *lat = latitude;
NSString *lon = longitude;
NSString *stateURLFinder = [NSString stringWithFormat:#"http://where.yahooapis.com/geocode?q=%#,+%#&gflags=R&flags=J&appid=zqoGxo7k", lat, lon];
//NSLog(stateURLFinder);
NSURL *stateURL = [NSURL URLWithString:stateURLFinder];
NSURLRequest *request = [[NSURLRequest alloc] initWithURL: stateURL];
connection = [[NSURLConnection alloc] initWithRequest:request delegate:self];
[request release];
}
return self;
}
-(void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
NSLog(#"didReceiveResponse");
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
NSLog(#"didFinishLoading");
}
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
NSLog(#"didFailWithError");
}
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)data
{
// Store incoming data into a string
NSString *jsonString = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
NSLog(jsonString);
// Yes, this is incomplete, but I was waiting for the method to fire before going
// any further. This will at least show me the JSON data being returned from yahoo
// in string format so I can output it to the console via NSLog
}
- (void)dealloc
{
[userState release];
[connection release];
[super dealloc];
}
#end
This is the current code I'm using and it works fine. All I did was include the connectionDidFinishLoading and didFailWithError methods to the original code. With regards to the connection being released before it was made, I used the code above as is without the previously mentioned methods and neither didReceiveData/didReceiveResponse would hit. It wasn't until those 2 methods were included that the methods began getting called. Not sure how, not sure why, but that was the only change among all of those suggested that worked. Big thanks to #Jiva DeVoe , #XJones , #jlehr and #Aby for all the tips/hints/suggestions!
Actually, I advise that you definitely do not use sendSynchronousRequest. You should always try to use asynchronous networking unless the app you're developing is a command line app without a run loop.
I suspect your problem may be that you're releasing the connection immediately, so it's never getting a chance to run. You should add a member variable and keep it around until you've received a response or whatever.
Bonus tip:
Guessing you're probably doing this for either iOS or the Mac, and writing GUI apps. These apps have run loops. When you use synchronous networking like the prior answer suggests, you prevent that runloop from executing. This means that if the request takes longer than a few seconds, your iOS app will be killed by the OS, and your Mac app will appear non-responsive. Neither of these are good results.
You're sending a release message to the connection before it's had a chance to run; don't do that. With regards to JSON, the string you said was returned from the server is JSON. Were you expecting something else?
Get rid of the line:
[connection scheduleInRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];
Once you've initialized the connection with the request it runs automatically. You have other problems as well. Your implementation of the NSURLConnectionDelegate protocol is wrong. You need to incrementally add data received in connection:didReceiveResponse to an NSMutableData object. You can convert it to JSON in `connectionDidFinishLoading:'.
As for the memory leak, release the connection in connectionDidFinishLoading: or connection:didFailWithError: You are guaranteed to receive one but not both of them.
Everything you need to know is here
[EDIT: added NSURLConnection code sample]
// Attach this to the touchUpInside event of a UIButton
// Note that all objects will be autoreleased
// Note that you can comment out any or all of the NSURLConnection delegate methods
// and the request will execute
- (IBAction)initiateRequest
{
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL urlWithString:#"http://www.google.com"]];
NSURLConnection *connection = [NSURLConnection connectionWithRequest:request delegate:self];
}
- (void)connection:(NSURLConnection *)connection didRecieveData:(NSData *)date
{
NSLog(#"connection:didReceiveData");
}
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
NSLog(#"connection:didReceiveResponse:");
}
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
NSLog(#"connectionDidFinishLoading:");
}
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
NSLog(#"connection:didFailWithError:");
}
Thanks to XJones for the suggestion. I wasn't including the two methods didFinishLoading or didFailWithError once inserted into my code, both didReceiveResponse and didReceiveData both began to hit. Thank you all for the tips, advice and suggestions and hopefully this helps someone else out down the road.
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?