I'm currently using a singleton as a data store for my app. I essentially store a number of events that are pulled and parsed from a web service and then added as needed. Each time I make a request from the web service, I parse the results and see if the items already exist. If they do, I delete them and add the updated version provided by the web service.
Everything appeared to be working properly until I fired up the Instruments panel to find out that my system is leaking the objects every time it loads them from the web service (from the second time on). The core method where things appear to be messing up is this one, which is located in my HollerStore singleton class:
- (void)addHoller: (Holler *)h
{
//Take a holler, check to see if one like it already exists
int i = 0;
NSArray *theHollers = [NSArray arrayWithArray:allHollers];
for( Holler *th in theHollers )
{
if( [[th hollerId]isEqualToString:[h hollerId]] )
{
NSLog(#"Removing holler at index %i", i);
[allHollers removeObjectAtIndex:i];
}
i++;
}
[allHollers addObject:h];
}
Quick explanation: I decided to copy the allHollers NSMutableArray into theHollers because it's being updated asynchronously by NSURLConnection. If I update it directly, it results in a crash. As such, I switched to this model hoping to solve the problem, however the Instruments panel is telling me that my objects are leaking. All the counts are exactly the # of items I have in my data set.
From what I can tell removeObjectAtIndex isn't effectively removing the items. Would love to get the thoughts of anybody else out there on three things:
Is my analysis correct that something else must be retaining the individual hollers being added?
Should I be using CoreData or SQLite for storing information pulled from the web service?
Do you know how long data stored in a Singleton should be available for? Until the app is killed?
Update
I think I've found the source, however perhaps someone can provide some clarity on the proper way to do this. I've created a method called parseHoller which takes a dictionary object created through SBJSON and returns my own model (Holler). Here are the last couple lines:
Holler *h = [[[Holler alloc] initFromApiResponse:hollerId
creatorId:creatorId
creatorName:creatorName
creatorImageUrl:creatorImage
comments:comments
attendees:attendees
wishes:wishes
invitees:invites
createdAt:createdAt
text:text
title:title
when:when]autorelease];
//(some other autorelease stuff is here to clean up the internal method)
return h;
I figured that since I'm returning an autoreleased object, this should be fine. Do you see anything wrong with this?
Have you tried to do a retain count on the objects that is leaking? Maybe that could clear up when or where it is being retained.
The code should be
[putObjectHere retainCount];
and then write to an NSLog
Hope it gives you something
Peter
Related
I have been working on an app where the user inputs data stored in core data everyday (two attributes an NSNumber and one as NSDate) and I wanted to improve that by allowing the user to import data from a external file such as csv or any other supported format through a button click. Any suggestions on how to proceed efficiently to do this?
Thank you.
Edit: Just adding a screenshot of the csv file as well as the output of the csv parser as NSArray. Basicly need to fetch the attribute separately and store them in core data on button click.
- The input file as csv:
- Sample csv parser output(NSarray):
I needed to achieve something similar recently.
A couple of members of my project team wanted to take our app prototype out to show potential clients, but wanted to show different data to each client. We solved this by allowing members of our project team to create their own test data before meeting with the client.
I achieved this by creating an example .csv file and distributing it to the other guys in the project team. They populate it with their own test data and use iTunes File Sharing to drop the .csv test data file on to the device.
On load, the app scans its Documents directory for a the test data file. If it exists, it parses the .csv file and persists to the database.
For the CSV parsing, I used Dave DeLong's CHCSVParser: https://github.com/davedelong/CHCSVParser
Plenty of help is available on setting up iTunes file sharing for your app. A quick Google finds this tutorial (http://www.raywenderlich.com/1948/how-integrate-itunes-file-sharing-with-your-ios-app) which should help you out, if you need it.
Edit- added help on storing data from .csv in Core Data
You stated in your original post that you store an NSNumber and NSDate. Taking that as a starting point, you might have a .csv file in the following form:
+----------------+--------------+
+ NSNumberColumn | NSDateColumn |
+----------------+--------------+
+ 1 | 2013-05-15 |
+ 2 | 2013-06-15 |
+ 3 | 2013-07-15 |
+----------------+--------------+
Assuming the output from the CSV parser is an NSArray of NSArrays, you could create the Core Data objects as follows:
I would create a couple of macros for the column numbers:
#define NSNumberColumn 0
#define NSDateColumn 1
Then iterate over the rows in the .csv file:
NSArray *rows = [NSArray arrayWithContentsOfCSVFile:pathToFile]; //CHCSVParser specific parsing method
for (NSArray *row in rows)
{
NSString *numberString = [parsedCsvRow objectAtIndex:NSNumberColumn];
NSString *dateString = [parsedCsvRow objectAtIndex:NSDateColumn];
NSNumber *number = // parse numberString to an NSNumber. Plenty of other posts on achieving this.
NSDate *date = // parse NSDate from dateString. Plenty of other posts on achieving this.
NSManagedObjectContext *context = [self managedObjectContext];
NSManagedObject *myCoreDataObject = [NSEntityDescription insertNewObjectForEntityForName:#"MyCoreDataObject" inManagedObjectContext:context];
[myCoreDataObject setValue:number forKey:#"NSNumberColumn"];
[myCoreDataObject setValue:date forKey:#"NSDateColumn"];
NSError *error;
if (![context save:&error]) {
NSLog(#"%#", [error localizedDescription]);
}
}
Note: Input validation and null checks have been ommited for brevity. I have also taken the liberty of making up your NSManagedObject property names, this will need updating. The above code should be separated in to a more suitable class structure.
I'm not at a Mac right now, so unfortunately I can't check if this works.
Hope that helps.
Try to use plist or json, they are already supported on iOS instead of CSV. CSV would require an third party parser. Using json or plist you will only need to loop throught the elemnts of the collections to create you persistent store. If you have just the CSV you can do a mid conversion using different free tools that you can find for free on the internet and later add to your bundle or publish to your site.
Here's what you do when you already have your CSV file parsed and data is ready to use in Objective-C.
Create a separate context for the import. You don't know how big the data can be, so you probably don't want to block one of your existing contexts while importing.
Iterate through the entries in the parsed data and insert new managed objects configured from each entry.
Every 200, 500, or 1000 entries (different for everybody, you'll need to test what's working best for you) save the context and, if needed, post a notification that a batch has been imported.
To keep the memory low, reset the context and forget all the objects that you created in this import context.
After the loop is finished, don't forget to save the last time.
Now how do you bring the data into another context, say, UI context?
This depends on the way you organized your Core Data stack. For example, import context can be configured as a child of the UI context. In this case, after each save to the import context the changes will be pushed to the UI context (and don't forget to save the UI context as well to push changes further).
But this is not the most efficient approach, because UI context, which is a context on the main thread, is involved in the import, and additional work is done on the UI thread that blocks it. I recommend creating the import context not as a child, but connected to the persistent store coordinator directly. To bring changes to the UI context in this case you either need to call mergeChangesFromContextDidSaveNotification: method after each save or you just refetch in the UI context after each save and in the end. The latter is easier on the UI context and particularly on NSFetchedResultsController, if you use it, because it doesn't need to replay changes to the updated objects one-by-one.
When I click a button, a UIAlertView prompts the user to type a name. This name is then created as a new 'Customer' object and inserted into a mutable array.
There is a separate mutable array called 'CustListByName', which stores a list of all names.
The problem im having is that when adding a second or third name, the app crashes. Sometimes it happens on the second try, other times on the third try. There is no information given in the debugger except for (lldb). The program reports EXC_BAD_ACCESS and then it dumps me to a screen with a bunch of assembly code.
The crash is happening in these lines of code:
Essentially, it clears the array of names and then repopulates it based upon the object array. I've studied in step by step with a breakpoint but everything seems correct up until the point of crash. It is also confusing why this happens on the second or third try, never the first.
[custListByName removeAllObjects];
for (Customer *object in custListByObject) {
[custListByName addObject:object->name];
}
Here is the code where a customer is created and inserted everytime the new customer button is clicked:
Customer *tempCust = [[Customer alloc] init];
tempCust->name =[[alertView textFieldAtIndex:0] text];
[custListByObject addObject:tempCust];
[tempCust release];
I would really appreciate help with this, thanks!
What I suspect is happening is that the UIPickerView is attempting to load a row using information from your customer array after you have already cleared it, and before you repopulate it. This would cause a bad access error.
What you may consider doing instead, is keeping two arrays, an NSMutableArray for loading the customers, and an NSArray as the actual data source for the UIPickerView. Then right before you reload the UIPickerView, you say:
dataSourceArray = [loadingArray copy];
[pickView reloadAllComponents];
Hopefully this helps.
Edit:
Here's what your updated code would look like if your loading array was called loadingCustListByName:
[loadingCustListByName removeAllObjects];
for (Customer *object in custListByObject) {
[loadingCustListByName addObject:object->name];
}
custListByName = [loadingCustListByName copy];
[pickView reloadAllComponents];
Doing this will ensure that the UIPickerView's datasource array always matches up with the number of rows it thinks it has.
I've scoured and still haven't found anything that quite works. Either the question/answer is too old or it simply hasn't worked for me. This is my first attempt at "my own" app. As it seems a right of passage, I'm making a checklist app. Here's what I'm looking for:
My Data Store contains 4 attributes: name, category, isChecked, isActive (more will surely follow as I expand)
When my View Controller initially loads, the NSFetchedResultsController has an NSPredicate that only retrieves the records whose attribute isActive is YES (or [NSNumber numberWithBool:YES). It then takes those records and displays them into the appropriate cells for the user. When a user clicks on a cell, the Data Store updates and changes the isChecked attribute accordingly. Everything works good to this point.
What I need to do now is to be able to remove the items (1 or more) from the list. Specifically, I need it to update the Data Store attributes isChecked and isActive to NO only if it's current isChecked attribute is YES. (I'm not looking to delete the record from the data store as they will be used to build up the database for the users future use.)
I've used, among other things:
[[[self fetchedResultsController] fetchedObjects]
setValue:[NSNumber numberWithBool:NO]
forKey:#"isChecked"];
This does actually work, it removes the checkmark(s) and updates the store accordingly. Problem is, not only am I making another request to the data store for the isActive items, it also searches the entire "Active List" that was fetched and sets each of their isChecked attributes to NO. This may not be too big of an issue for small lists, but as the list(s) expand this can be an issue.
The other problem is, if I add:
[[[self fetchedResultsController] fetchedObjects]
setValue:[NSNumber numberWithBool:NO]
forKey:#"isActive"];
It sets ALL of my list items to NO (as well as a second data store request within the same method.)
So my question is: How can I get through the list, find only the items that are checked and update only those records (set both the isChecked && isActive attributes = NO) whose isChecked attribute is YES rather than working through the entire list?
I've tried creating a separate fetchedResultsController specifically for this buttons action, and it did work (that is to say, it didn't crash) but the debugger popped out a rather large 'Serious Application Error'. I won't post the error message as it's long and most likely irrelevant to any solution.
Any assistance would be greatly appreciated. Thanks in advance and please be gentle :-].
EDIT
I have tried using a for loop, for (NSString *item in fetchedResultsController) but I get the error ...may not respond to 'countByEnumeratingWithState:objects:count'
It seems a loop of sorts is what's needed here, but again, nothing I can find is relevant or it's outdated. Again, thanks for any assistance.
Edit 2
Here is the original error I got when I ran a second separate fetchRequestController for this button/method:
An exception was caught from the delegate of NSFetchedResultsController during a call to -controllerDidChangeContent:. Invalid update: invalid number of rows in section 0. The number of rows contained in an existing section after the update (4) must be equal to the number of rows contained in that section before the update (4), plus or minus the number of rows inserted or deleted from that section (0 inserted, 3 deleted) and plus or minus the number of rows moved into or out of that section (0 moved in, 0 moved out). with userInfo (null)
You can just loop over the fetchedObjects collection and change the managed objects. After changing them you'll need to reload your list (I guess you use a tableview).
I don't know what your classes are named, but in general you can just loop over the collection of managed objects and change them. Remember that you need to save your managed object context if you want to keep these changes for when the app closes.
NSArray* myCollection = [[self fetchedResultsController] fetchedObjects];
for(ActiveListData *managedObject in myCollection)
{
if(managedObject != nil && managedObject.isChecked)
{
managedObject.isChecked = NO;
managedObject.isActive = NO;
}
}
If you want to do the check on all object in the database you'll need a new method in your NSFetchedResultsController that has a predicate checking on isChecked and then loops over and edits the result collection.
You might want to post your error code as we could be able to point out what you did wrong.
Edit: If you're not familiar with using Core Data the apple documentation provides a lot of information: http://developer.apple.com/library/mac/#documentation/cocoa/Conceptual/CoreData/Articles/cdBasics.html
Thanks to #ggfela for his answer. The processes of his answer were spot on. Here is the actual code I put into my button/method, in hopes of it helping someone else in the future:
NSArray *moc = [[self fetchedResultsController] fetchedObjects];
for (ActiveListData *item in moc) {
if (item != nil && item.isChecked.boolValue == 1) {
item.isChecked = [NSNumber numberWithBool:NO];
item.isActive = [NSNumber numberWithBool:NO];
}
}
// Call to Data Store to update the list
NSError *error;
if (![self.managedObjectContext save:&error]) {
FATAL_CORE_DATA_ERROR(error);
return;
Explanation:
Load the contents of the result from calling the fetchedResultsController method into a temporary variable named moc
Use a for loop to cycle through the array of moc. ActiveListData is the NSManagedObject subclass that I created for my Core Data and is the proper place to insert the separated values/attributes from the data store. From there, it's pretty simple, I ensure that item is not nil AND that the item's attribute is the value I need.
NOTE
Core Data does not store the bool values YES and NO but rather 1 and 0, respectively but when you call or compare the values, you simply can not compare the value of item.isChecked because it is being passed back to you as a bool not as an integer. You can not simply compare item.isChecked == YES either since the #property of isChecked is an NSNumber. So, in the case of the if I put item.isChecked.boolValue as this will give me the representing integer for it's bool value, in this case I have it check for a 1 (YES). (Sorry if my explanation is wrong and/or confusing, but this is how I understand it and is the only way this code works.)
Then, setting the new values of these attributes is like you would expect when setting any other variable. The only "tricky" difference with this is that the NSManagedObject subclass sets the #property of the isChecked and isActive to an NSNumber (as mentioned earlier) so in order to send the proper values back to Core Data you use the method numberWithBool of the NSNumber class.
And just in case anyone gets confused by my FATAL_CORE_DATA_ERROR(error) call this is simply a macro that was defined inside the Prefix.pch file to handle my errors from the managedObjectContext. You can use any (or none) error handling you choose.
Thanks again #ggfela for your help!! If anyone else has any other suggestions on how this code should be applied, then please let me know!
You can use NSBatchUpdateRequest to update multiple records
Examples:
https://www.bignerdranch.com/blog/new-in-core-data-and-ios-8-batch-updating/
http://code.tutsplus.com/tutorials/ios-8-core-data-and-batch-updates--cms-22164
I'm trying to implement openFlow in my project but I cant seem to get the images to show up on my uiview. What isnt clear to me is once I have the dictionary of image links, how do i tell AFOpenView that I want to use that dictionary object as my data source?
I've looked at the demo code and I see that when the flickr request finishes, he saves a copy of the dictionary results, counts them, and then tells OpenFlowView that there are x number of images, but what is never clear is how he tells OpenFlowView to use the dictionary with the results?
- (void)flickrAPIRequest:(OFFlickrAPIRequest *)inRequest didCompleteWithResponse:(NSDictionary *)inResponseDictionary
{
// Hold onto the response dictionary.
interestingPhotosDictionary = [inResponseDictionary retain];
int numberOfImages = [[inResponseDictionary valueForKeyPath:#"photos.photo"] count];
[(AFOpenFlowView *)self.view setNumberOfImages:numberOfImages];
}
See here: http://blog.objectgraph.com/index.php/2010/04/09/how-to-add-coverflow-effect-on-your-iphone-app-openflow/
This tutorial seems to suggest that you have to call the view's setImage method multiple times, once per image.
This tells me that the implementation is confusing and weird, but for this you have to blame the component's author.
The images are loaded on demand in the 'updateCoverImage:' method of AFOpenFlowView.m
'updateCoverImage:' calls 'openFlowView:requestImageForIndex:' in AFOpenFlowViewController.m, which uses interestingPhotosDictionary.
So, it is called on demand whenever an image needs to be loaded. It wraps an operation queue so the images are loaded outside the main thread.
I have an application that downloads an xml file, parses the file, and creates core data objects while doing so. In the parse code I have a function called 'emptydatacontext' that removes all items from Core Data before creating replacements items from the xml data. This method looks like this:
-(void) emptyDataContext
{
NSFetchRequest * allCon = [[NSFetchRequest alloc] init];
[allCon setEntity:[NSEntityDescription entityForName:#"Condition" inManagedObjectContext:managedObjectContext]];
NSError * error = nil;
NSArray * conditions = [managedObjectContext executeFetchRequest:allCon error:&error];
DebugLog(#"ERROR: %#",error);
DebugLog(#"RETRIEVED: %#", conditions);
[allCon release];
for (NSManagedObject * condition in conditions) {
[managedObjectContext deleteObject:condition];
}
// Update the data model effectivly removing the objects we removed above.
//NSError *error;
if (![managedObjectContext save:&error]) {
DebugLog(#"%#", [error domain]);
}
}
The first time this runs it deletes all objects and functions as it should - creating new objects from the xml file. I created a 'update' button that starts the exact same process of retrieving the file the proceeding with the parse & build. All is well until its time to delete the core data objects. This 'deleteObject' call creates a "EXC_BAD_ACCESS" error each time. This only happens on the second time through.
Captured errors return null. If I log the 'conditions' array I get a list of NSManagedObjects on the first run. On the second this log request causes a crash exactly as the deleteObject call does.
I have a feeling it is something very simple I'm missing or not doing correctly to cause this behavior. The data works great on my tableviews - its only when trying to update I get the crashes.
I have spent days & days on this trying numerous alternative methods. Whats left of my hair is falling out. I'd be willing to ante up some cash for anyone willing to look at my code and see what I'm doing wrong. Just need to get past this hurdle.
Thanks in advance for the help!
Did you save the context after removing the objects in the for loop? Be aware that deleteObject: does not delete the object immediately, it simply schedule it for deletion when changes are committed, i.e., when you save the context.
EDIT: Your problem may be related to how you present your data to the user on your table view. Without additional code is difficult to tell exactly (are you using NSFetchedResultsController or not?), but my guess is that the interaction between deleting the data and showing them on the table is not correct. Probably, what is happening is that your table is told to visualize your data, but then, when you delete them, you are not updating correctly the table.
Wow, so after a few days of testing I went down a path that led me to tracking down Zombies & memory mgmt. This was a situation where the errors I was recieving were leftover from issues in another area. When parsing the data and placing it into Core Data I released an object that was to be autoreleased. So any subsequent calls to that item within core data (save, deletec, etc) caused a crash. Thank you all for your help and I vow to pay closer attention with my memory mgmt calls.