I'm trying to use MBProgressHUD to show a loading animation while I'm accessing information to smooth out the process of going from a UITableView listing to a UIWebView that has detailed information of the item selected. If I call [self fetchPlayer]; without using MBProgressHUD I have no issues and everything works fine albeit without the animation. But if I call [self loadingAnimation]; it half works. The first time I select something from the UITableView it loads correctly every time, but if I go back and select the same or different item I will quite often get null values for playerDetails items. I'm not sure what the MBProgressHUD method could be doing to cause this but here is the code. The NSLog is displaying the correct information - but the main class that is calling the two methods does not output it correctly.
- (void)loadingAnimation {
// The hud will dispable all input on the view (use the higest view possible in the view hierarchy)
HUD = [[MBProgressHUD alloc] initWithView:self.navigationController.view];
// Add HUD to screen
[self.navigationController.view addSubview:HUD];
HUD.labelText = #"Loading";
// Show the HUD while the provided method executes in a new thread
[HUD showWhileExecuting:#selector(fetchPlayer) onTarget:self withObject:nil animated:YES];
}
- (void)fetchPlayer {
NSManagedObjectContext *pcontext = [[AppController sharedAppController] managedObjectContext];
NSFetchRequest *pfetch = [[NSFetchRequest alloc] init];
NSEntityDescription *pentity = [NSEntityDescription entityForName:#"Players"
inManagedObjectContext:pcontext];
[pfetch setEntity:pentity];
NSPredicate *ppredicate = [NSPredicate predicateWithFormat:#"playerID=%#", [playerNews playerID]];
[pfetch setPredicate:ppredicate];
NSError *perror;
NSArray *plist = [pcontext executeFetchRequest:pfetch error:&perror];
playerDetails = [plist objectAtIndex:0];
NSLog(#"%# %# %# %# %#", [playerNews playerID],
[playerDetails valueForKey:#"playerFirstName"],
[playerDetails valueForKey:#"playerLastName"],
[playerDetails valueForKey:#"position"],
[playerDetails valueForKey:#"dateOfBirth"]);
[pfetch release];
NSManagedObjectContext *context = [[AppController sharedAppController] managedObjectContext];
NSFetchRequest *fetch = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Teams"
inManagedObjectContext:context];
[fetch setEntity:entity];
if (![playerDetails valueForKey:#"team"]) {
team = [playerDetail team];
} else {
team = [playerDetails valueForKey:#"team"];
}
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"team=%#", team];
[fetch setPredicate:predicate];
NSError *error;
NSArray *list = [context executeFetchRequest:fetch error:&error];
playerTeam = [list objectAtIndex:0];
[fetch release];
}
This seems to be at least a problem with threading. You are sharing your context across multiple threads as fetchPlayer is executed in a background thread by MBProgressHUD.
Create a new Context in the background thread and make sure NSManagedObjects are not shared across threads.
Related
I want to insert 200 5Mb records in my Core Database. But when I save the NSManagedObject, the memory wasn't released (autoreleased pool didn't help), and after inserting 30 records I got the memory warning and the application crashed. Here is my code
- (void)SaveItem
{
NSString *entityName = kEntityName;
AppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];
NSManagedObjectContext *context = appDelegate.managedObjectContext;
NSEntityDescription *entityDesctiption = [NSEntityDescription
entityForName: entityName
inManagedObjectContext:context];
// check if town exists
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"id == %d", self.imageID];
NSFetchRequest *requestToCheckExistense = [[NSFetchRequest alloc] init];
[requestToCheckExistense setEntity:entityDesctiption];
[requestToCheckExistense setPredicate:predicate];
NSArray *objects = [context executeFetchRequest:requestToCheckExistense error:nil];
[requestToCheckExistense release];
if (objects == nil)
{
NSLog(#"there was an error");
}
NSManagedObject *object;
if ([objects count] > 0)
{
// edit item
object = [objects objectAtIndex:0];
}
else
{
// if object doesn't exist, find max id to imlement autoincrement
NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity:entityDesctiption];
request.propertiesToFetch = [NSArray arrayWithObjects: #"id", nil];
NSArray *allobjects = [context executeFetchRequest:request error:nil];
[request release];
NSInteger newID = 1;
if ([allobjects count] > 0)
{
NSNumber *maxID = [allobjects valueForKeyPath:#"#max.id"];
newID = [maxID intValue] + 1;
}
// write item
object = [NSEntityDescription insertNewObjectForEntityForName:entityName inManagedObjectContext:context];
[object setValue:[NSNumber numberWithInt:newID] forKey:#"id"];
self.imageID = newID;
}
// fill NSManagedObject
// size of objNSData is about 5MB
NSMutableData *objNSData = [[DatabaseManager sharedDatabaseManager] encryptedDataFromImage:bigImage];
[object setValue:objNSData forKey:#"big"];
[context save:nil];
}
When I commented
[object setValue:objNSData forKey:#"big"];
everything was OK.
I tried to add the code into #autoreleasepool , but that didn't help.
I know, that now, when I save data to database, it's still in iPhone RAM. How to release it from this memory? When I get a set of Managed Objects from the database, they are not in the RAM (I can easyly get 100 object, each of them has 5Mb fields)
object =(tblEntity *) [NSEntityDescription insertNewObjectForEntityForName:entityName inManagedObjectContext:context];
try to type cast the object,this may solve the problem
I've solved the issue.
after call of [self SaveItem];
I used
[context save];
[context reset];
[context save];
all the NSManagedObjects from the context will be released.
After that operation I can add as many big objects as I want
Because you don't own an NSManagedObject when you create it, it may be retained by the core data stack even after releasing it (when using an autoreleasepool contained inside the loop).
This may help:
Set the undo manager of your managedobjectContext to nil:
[context setUndoManager:nil];
Be sure that no properties of that object are retained anywhere, because then the managed object will not be released on time inside your loop.
Be sure to add an autorelease pool inside every loop execution, not wrapping all the loop itself, similar to:
for(i;i<n;i++) {
NSAutoreleasePool* pool = [[NSAutoreleasePool alloc] init];
[obj saveItem];
[pool drain];
}
If that object belongs to a hierarchy of NSManagedObjects, then you need to release the owner of this object too, for this one to be deallocated from memory.
You can check apple's documentation about memory management in CoreData.
Warning: big objects (> 1MB) are not recommended by Apple to be stored inside CoreData (Check this other question/answer.)
I'm facing a strange issue. I have a method which populates an array with some data (fetchData) (quite a lot actually and it's a bit slow). I'm using the array to build the rows of the table.
I've tried calling fetchData in a number of places in my code, at various times in the construction of the view and I always seem to get the following: a black screen which is shown until the data from the array is loaded. I've called fetchData from the following:
(void)viewDidLoad;
(void)viewWillAppear:(BOOL)animated;
(void)viewDidAppear:(BOOL)animated;
Since I'm using a navigation view controller, having the app appear to hang is pretty bad looking since it gets stuck on a black screen. What I was hoping my code would achieve was displaying an empty table, with a progress indicator until the data is loaded - then refresh. Unfortunately I'm not getting this far since the view isn't being loaded no matter where I call fetchData.
Help appreciated!
P.S. To get around this problem I even tried using a TTTableViewController, but the Loading view is never displayed. Typical. sigh
Your load method must be blocking the UI. You should move it to another thread and let the data load there. You can instantiate the thread in viewDidLoad.
This is a skeleton code for that you need to (using GCD)
dispatch_queue_t downloadQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_async(downloadQueue, ^{
... Move all the loading part here.
dispatch_async(dispatch_get_main_queue(),^{
... Do all the UI updates, mostly, [tableView reloadData];
})
})
It possible that you could add a timer to delay the call somewhere in your viewDidAppear method. For example:
- (void)viewDidAppear:(BOOL)animated {
[NSTimer scheduledTimerWithTimeInterval:1.0 target:self selector:#selector(fetchData) userInfo:nil repeats:NO];
}
This will give your app time to load the UI and start your loading screen, then start fetching the data later. You can also try fetching the data in a background thread if you would prefer to go that route
I was having the same issue with a table view not loading initially, but it worked n another .m file I had. Here is the one that worked:
add this to your viewDidLoad:
NSError *error = nil;
if (![[self fetchedResultsController] performFetch:&error]) {
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
and this to the implementation block:
#pragma mark -
#pragma mark Fetched results controller
- (NSFetchedResultsController *)fetchedResultsController {
if (fetchedResultsController == nil) {
// Create the fetch request for the entity.
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
// Edit the entity name as appropriate.
NSEntityDescription *entity = [NSEntityDescription entityForName:#"OMFrackinG" inManagedObjectContext:managedObjectContext];
[fetchRequest setEntity:entity];
// grouping and sorting optional
//NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"country" ascending:YES];
NSSortDescriptor *sortDescriptor1 = [[NSSortDescriptor alloc] initWithKey:#"state" ascending:YES];// was name
NSSortDescriptor *sortDescriptor2 = [[NSSortDescriptor alloc] initWithKey:#"name" ascending:YES];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor1,sortDescriptor2, nil];
[fetchRequest setSortDescriptors:sortDescriptors];
propriate.
NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:managedObjectContext sectionNameKeyPath:#"state" cacheName:nil];//#"state"
aFetchedResultsController.delegate = self;
self.fetchedResultsController = aFetchedResultsController;
[aFetchedResultsController release];
[fetchRequest release];
[sortDescriptor1 release];
[sortDescriptor2 release];
[sortDescriptors release];
}
return fetchedResultsController;
}
I basically have the core data and the app working correctly except for the code in the AppDelegate. The code I'm having problems with is the following:
- (void)applicationDidFinishLaunching:(UIApplication *)application {
RootViewController *tableController = [[RootViewController alloc] initWithStyle:UITableViewStylePlain];
tableController.managedObjectContext = [self managedObjectContext];
self.navigationController = [[UINavigationController alloc] initWithRootViewController:tableController];
[tableController release];
[window addSubview: [self.navigationController view]];
[window makeKeyAndVisible];
}
I don't want to make the managedObjectContext the root view controller upon launch. I'm wanting to make it another view controller. However, if I change the classes to the view controller that I'm needing it for, it loads that view controller upon launch of the app, which is not what I want to do. I still want to launch the root view but I want to be able to load the core data context for my other view controller. I'm really confused on how to fix this issue. I've spent 2 days so far trying to find a way to fix this but no luck yet. Any help would be appreciated.
Also, if I leave out the following in the appdelegate didfinishlaunching:
RootViewController *tableController = [[RootViewController alloc] initWithStyle:UITableViewStylePlain];
tableController.managedObjectContext = [self managedObjectContext];
self.navigationController = [[UINavigationController alloc] initWithRootViewController:tableController];
[tableController release];
I get this error:
Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: '+entityForName: could not locate an NSManagedObjectModel for entity name 'Hello'
EDIT:
Here is the entity code:
- (void)viewDidLoad {
[super viewDidLoad];
self.title = #"Lap Times";
UIBarButtonItem *addButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:#selector(addTime:)];
self.navigationItem.rightBarButtonItem = addButton;
[addButton release];
[self fetchRecords];
}
- (void)addTime:(id)sender {
addTimeEvent *event = (addTimeEvent *)[NSEntityDescription insertNewObjectForEntityForName:#"addTime" inManagedObjectContext:self.managedObjectContext];
[event setTimeStamp: [NSDate date]];
NSError *error;
if (![managedObjectContext save:&error]) {
// This is a serious error saying the record could not be saved.
// Advise the user to restart the application
}
[eventArray insertObject:event atIndex:0];
[self.tableView reloadData];
}
- (void)fetchRecords {
// Define our table/entity to use
NSEntityDescription *entity = [NSEntityDescription entityForName:#"addTime" inManagedObjectContext:self.managedObjectContext];
// Setup the fetch request
NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity:entity];
// Define how we will sort the records
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"timeStamp" ascending:NO];
NSArray *sortDescriptors = [NSArray arrayWithObject:sortDescriptor];
[request setSortDescriptors:sortDescriptors];
[sortDescriptor release];
// Fetch the records and handle an error
NSError *error;
NSMutableArray *mutableFetchResults = [[managedObjectContext executeFetchRequest:request error:&error] mutableCopy];
if (!mutableFetchResults) {
// Handle the error.
// This is a serious error and should advise the user to restart the application
}
// Save our fetched data to an array
[self setEventArray: mutableFetchResults];
[mutableFetchResults release];
[request release];
}
Also if I use my own appdelegate called MyAppDelegate
MyAppDelegate *tableController = [[MyAppDelegate alloc] initWithStyle:UITableViewStylePlain];
tableController.managedObjectContext = [self managedObjectContext];
self.navigationController = [[UINavigationController alloc] initWithRootViewController:tableController];
I get the following error:
Object cannot be set- either readonly property or no setter found
I can't see the problem with the original approach you are taking? You are basically creating the managedObjectContext in your App delegate and passing it on to the tableController via assignment.
The alternative way to go about it is to get your viewController to "ask" for the managedObjectContext from the App delegate. So you'd still have your CoreData methods placed in your AppDelegate and use the following where you want to get a reference to the context. Because the managedObjectContext is lazily loaded on request, it will only get instantiated the first time you access the managedObjectContext method in your app delegate.
AppDelegate *theDelegate = (AppDelegate*)[[UIApplication sharedApplication] delegate];
self.managedObjectContext = theDelegate.managedObjectContext;
PS1: obviously you need to replace AppDelegate with the correct name for your App.
PS2: the reason you're getting the error when you make the changes is that there is no context available for CoreData to work with.
There is nothing magical about the RootViewController beside the name. You can rename it or you can exchange it with any other View Controller as long as these View Controller are configured right. You might want to take the RootViewController and adjust your new View Controller accordingly.
That said I don't understand what you want to do. You might want to post the code that doesn't work.
if you get an exception for +entityForName: you should post the code around +entityForName:.
If I had to make a guess I would say that your code looks like this:
entity = [NSEntityDescription entityForName:#"Hello"
inManagedObjectContext:managedObjectContext];
^^^^^^^^^^^^^^^^^^^^
this means you are using the managedObjectContext without the getter. And the getter uses lazy loading to load the context if it is needed for the first time.
I bet managedObjectContext is nil at this point. Use the debugger to check this out.
And then change the line like this:
entity = [NSEntityDescription entityForName:#"Hello"
inManagedObjectContext:self.managedObjectContext];
^^^^^^^^^^^^^^^^^^^^^^^^^
The code works when you include the four line about the rootviewcontroller because of this call:
tableController.managedObjectContext = [self managedObjectContext];
^^^^^^^^^^^^^^^^^^^^^^^^^^^
this will create the context if it is nil. Lazy loading.
[self managedObjectContext] is the same as self.managedObjectContext
but everything in my post is a guess because you didn't include the code around +entityForName:inManagedObjectContext:
I have some NSOperations subclasses that handle CoreData imports. I believe i've ticked most of the non-main thread issues
I create my own autorelease pool in the
main method
I create a NSManagedObjectContext for each
operation
These operations are loaded into a NSOperationQueue, with the maximum number of concurrent operations set 1.
The code works perfectly on a iOS 4.0.1, however on a iOS 3.1.3 device a get a lot of log messages like the following
*** _NSAutoreleaseNoPool(): Object 0x5f926c0 of class NSCFDictionary autoreleased with no pool in place - just leaking
NSOperation Subclass main method
-(void) main{
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
#try {
//Start Operation
//====================================
NSManagedObjectID *objID = nil;
NSError *err = nil;
id user = nil;
if( !(userID = [self __lookup:[self userID] inContext: [self threadContext]]) ){
//Set the name of the element
user = [[self threadContext] objectWithID:objID];
//Update the name
[user setValue:#"John Doe" forKey:#"name"];
[user setValue:#"Hello world" forKey:#"status"];
}
if( ![[self threadContext] save:&err] ){
DebugLog(#"Couldn't savechanges %#", err);
}
//====================================
//End Operation
}
#catch (NSException * e) {
DebugLog(#"Exception %#",e);
}
//====================================
[pool drain];
}
The __lookup:inContext: method
-(NSManagedObjectID*) __lookup:(id)aID inContext:(NSManagedObjectContext*) aContext{
NSPredicate *predicate = nil;
NSEntityDescription *entity;
NSFetchRequest *fetchRequest = nil;
NSError *err = nil;
predicate = [NSPredicate predicateWithFormat:#"userID == %#",aID];
entity = [NSEntityDescription entityForName:#"User" inManagedObjectContext:aContext];
fetchRequest = [[[NSFetchRequest alloc] init] autorelease];
[fetchRequest setPredicate:predicate];
[fetchRequest setEntity:entity];
//Only fetch id's for speed
[fetchRequest setResultType:NSManagedObjectIDResultType];
return [[aContext executeFetchRequest:fetchRequest error:&err] lastObject];
}
Most of the other methods instance methods, ie threadContext look similar to the __lookup:inContext: method. I'm aware that i don't create Autorelease pools for the instance methods, but according to my understanding of how autorelease works, as long as these methods are only called inside the main method, after the NSAutoreleasePool has been created, the outer most pool should be used. I create objects such as the NSManagedObjectContext lazily, and in most cases don't use the start method
Solved it, This operation was launching a NSURLConnection using the advice in an article by Dave Dribin. However, where possible i try to never cut and paste other peoples code, so i can always filter what i am putting into my own code.
Turns out i forgot to add this check
if( ![NSThread isMainThread] ){
[self performSelectorOnMainThread:#selector(start)
withObject:nil
waitUntilDone:NO];
return;
}
Which ensures that the start method runs on the main thread, where a NSAutoreleasePool already exists. Simple mistake, easy solution.
I'm stuck trying to figure out how to modify the data contained on the persistent store.
I'm writing an application with several views using a UITabBarController, my core data methods are located mainly on the main application delegate but I will only be using this data from the UItableViewController view.
In order to use the managedObjectContext created in the main application delegate from the UITableViewController I use the following on the viewDidLoad: method:
MessageAppDelegate *appDelegate = (MessageAppDelegate *)[[UIApplication sharedApplication] delegate];
managedObjectContext = [appDelegate managedObjectContext];
The application then displays some messages in the table and when a user selects a UITableViewCell (didSelectRowAtIndexPath) I get the ID of the message object and call the following method:
[self readMessage:pk];
-(void)readMessage:(NSInteger)pk {
// First I select the data
NSFetchRequest *request = [[NSFetchRequest alloc] init];
// had to setReturnsObjectsAsFaults to NO so I could access the message data
[request setReturnsObjectsAsFaults:NO];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Message" inManagedObjectContext:self.managedObjectContext];
[request setEntity:entity];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"pk == %d", pk];
[request setPredicate:predicate];
NSError *error;
NSArray *items = [self.managedObjectContext executeFetchRequest:request error:&error];
[request release];
// Then I update the object
for (Message *thisMessage in items) {
//I display the message to the console before updating to check the value
DLog(#"before reading message %#", thisMessage);
// we set the message flat to YES
[thisMessage setRead:YES];
// we set some sample text here (just for testing)
[thisMessage setMessageText:#"New message text"];
// I then display the message to the console checking that the flag and text has been updated
DLog(#"read message %#", thisMessage);
}
// Finally I save the updated message calling the function posted below
[self saveMOC];
}
- (void)saveMOC {
NSError *error;
if (![managedObjectContext save:&error]) {
NSLog(#"there was an error saving the message!");
}
}
After that the data gets updated correctly and if I fetch the data from the managedObjectContext after saving it I get the correct values.
I verified this by adding the following code to at the end of readMessage method:
request = [[NSFetchRequest alloc] init];
//required to avoid presenting objects as faults!!
[request setReturnsObjectsAsFaults:NO];
entity = [NSEntityDescription entityForName:#"Message" inManagedObjectContext:[self managedObjectContext]];
[request setEntity:entity];
//Set the sort descriptor
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"pk" ascending:NO];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
[request setSortDescriptors:sortDescriptors];
[sortDescriptors release];
[sortDescriptor release];
//Execute the request
NSMutableArray *mutableFetchResults = [[self.managedObjectContext executeFetchRequest:request error:&error] mutableCopy];
if (mutableFetchResults == nil) {
// Handle the error later
DLog(#"ERROR: Unable to fetch the results");
}
[self setMessagesArray:mutableFetchResults];
NSLog(#"Data now is: %#", mutableFetchResults);
[mutableFetchResults release];
[request release];
The problem is that if I exit from the application and launch it again all my messages lose the read property (or any other changes I make) and the tableview loads the data as it was first saved onto the persistent store.
Try this and see if the object changes are actually being saved
- (void)saveMOC {
NSError *error;
if (![managedObjectContext save:&error]) {
NSLog(#"there was an error saving the message!");
} else {
NSLog(#"The message was saved!");
}
}
So for each call of saveMOC which is successful, you should see a console message. If it is being called and you're seeing the messages, then you must not be altering the 'read message' property. You could check this by inspecting the value of the 'read message' property before and after setting it either using a breakpoint or by using NSLog messages to print its value
Is -readMessage: method defined in your app delegate or in your view controller? My guess is that you're changing properties of an object in different managed object context than one where you try to save changes (MOC in your app delegate), which actually doesn't have an idea that something has changed. On the other hand, MOC which keeps your changes is never saved (changes are kept only in memory) and that for your changes are lost after you restart your app.
Can this be the situation?