I'm using an NSFetchRequest to get all core data entities in a context, and I'm moving them to another context.
This works fine doing it with just 1 entity. I can iterate through results very quickly. The entity has a relationship with another entity however, so I need to run a second NSFetchRequest to get the entities which are joined by this relationship. It's the second NSFetchRequest which is causing the crash. The crash just makes the app quit to the homescreen and no errors appear in the xcode log. I've commented out my code to figure out that this is the problem, and have got it down to this:
NSError *error;
NSFileManager *manager = [NSFileManager defaultManager];
NSManagedObjectContext *oldContext = [self version1ManagedObjectContext];
TICDSSynchronizedManagedObjectContext *newContext = [self version1_1ManagedObjectContext];
NSFetchRequest *oldFetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *oldEntryEntity = [NSEntityDescription entityForName:#"Entry"
inManagedObjectContext:oldContext];
[oldFetchRequest setEntity:oldEntryEntity];
[oldFetchRequest setFetchBatchSize:10];
NSArray *entrys = [oldContext executeFetchRequest:oldFetchRequest error:&error];
int totalEntries = [oldContext countForFetchRequest:oldFetchRequest error:nil];
NSLog(#"total entries: %i", totalEntries);
int i = 0;
while (i < totalEntries) {
#autoreleasepool {
Entry *entry = [entrys objectAtIndex:i];
Entry *newEntry = [NSEntityDescription
insertNewObjectForEntityForName:#"Entry"
inManagedObjectContext:newContext];
//Taking out this fetch request means it functions fine
NSFetchRequest *mediaRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *mediaEntity = [NSEntityDescription
entityForName:#"Media"
inManagedObjectContext:oldContext];
[mediaRequest setEntity:mediaEntity];
NSPredicate *predicate = [NSPredicate predicateWithFormat:
#"(entry == %#)", entry];
[mediaRequest setPredicate:predicate];
NSArray *mediaItems = [oldContext executeFetchRequest:mediaRequest error:&error];
int totalMediaItems = [oldContext countForFetchRequest:mediaRequest error:nil];
NSLog(#"total media items: %i", totalMediaItems);
int i2 = 0;
while (i2 < totalMediaItems) {
#autoreleasepool {
Media *newMedia = [NSEntityDescription
insertNewObjectForEntityForName:#"Media"
inManagedObjectContext:newContext];
i2++;
}
}
[newContext save:&error];
i++;
}
}
Any ideas why this might be crashing my app?
In answer to any questions about what I'm trying to do - I'm trying to migrate data between 2 versions. Standard data migration, using mapping, does not work with large data, such as NSData.
I believe that there are few more code lines that you don't expose here. The ones where you copy the data from the old entities to the new ones...
Maybe the problem is there.
Anyway, I would add NSLog between every 2 lines of code and see which is the last one that is printed...
I think that something is autoreleased in the inner loop and you try to use it in the next iteration.
I suggest that you edit the scheme that you are using to build and enable everything for the diagnostics tab. This will probably spit out whatever might be causing the issue.
Related
I want to deal with a data attribute, named originalImage in every Media entity in the store.
The problem is that despite the autoreleasing, memory builds up every time it's accessed via valueForKey, and eventually the app crashes. Or perhaps it's loading large individual NSData items which is the problem, but Instruments shows it to be a steadily inclining graph of memory usage, until it eventually gives me a memory warning and then crashes.
I haven't started on the rest of the code for this yet, so i'm not performing some hidden task that i'm not showing you.
NSFetchRequest *request = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Media"
inManagedObjectContext:[self managedObjectContext]];
[request setEntity:entity];
[request setFetchBatchSize:10];
NSArray *mediaItems = [[self managedObjectContext] executeFetchRequest:request error:nil];
for (NSManagedObject *media in mediaItems) {
#autoreleasepool {
[media valueForKey:#"originalImage"];
}
}
EDIT: Today it seems that even just mentioning the NSManagedObject media is enough to cause this media leak. So even without the valueForKey line, i have a leak. I've tried this:
while (i < count) {
#autoreleasepool {
NSManagedObject *media = [mediaItems objectAtIndex:i];
[[self managedObjectContext] refreshObject:media mergeChanges:NO];
NSLog(#"i: %i", i);
i++;
}
}
This also didn't work, and crashed at the same point.
Did you try something like:
for(int i=0;i<[mediaItems count]; i++) {
#autoreleasepool {
NSManagedObject *media = [mediaItems objectAtIndex:i];
[media valueForKey:#"originalImage"];
}
}
Maybe this way "media" gets released properly at every loop.
(Sorry, I put this on a comment. I'm new on SO and not enough rep.)
I have Core Data setup in my app and need to fetch a bunch of items and then access the properties I choose of those fetched items. I am able to successfully fetch a bunch of results like this:
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"TableInfo" inManagedObjectContext:managedObjectContext];
[fetchRequest setEntity:entity];
NSError *error = nil;
NSArray *result = [managedObjectContext executeFetchRequest:fetchRequest error:&error];
This gives me an array with my results, great. Now from this how can I for example get the 'name' property from these results? In this specific circumstance I want to load an array with all of the fetched results 'name' strings.
If I read your question correctly, you are able to fetch your NSManagedObjects without difficulty, but would like to derive another NSArray with name properties on those managed objects?
Then you can use the valueForKeyPath on the NSArray (extending your original code):
NSArray *names = [result valueForKeyPath:#"name"];
You can use the key-value:
for (NSManagedObject *fetchedResult in result) {
NSLog(#"name = %#", [fetchedResult valueForKey:#"name"]);
}
or if you created your custom NSManagedObject:
for (EntityObject *fetchedResult in result) {
NSLog(#"name = %#", [fetchedResult name]);
}
I am working with several NSManagedObject types with several relationships. How can I tell Core Data to automatically populate object IDs for me? I'm looking for something like an index key in SQL, so that no two instances of a given object are allowed to have the same ID.
Edit:
I'd like for all of my "Account" objects to have unique IDs on them. I was just adding one to the `countForFetchRequest, but I realized that when deleting the second to last object and then adding one, the last two objects now have the same IDs.
How can I ensure that a given value has a unique value for all instances of my "Account" NSManagedObject?
EDIT2:
I need to have a separate ID for sorting purposes.
All NSManagedObjects automatically have a unique NSManagedObjectID. There is no notion of a custom auto-incrementing attribute, but it's certainly easy to write one yourself.
The way I resolved this is with Core Data aggregates. I actually end up assigning the ID myself.
Essentially, I query Core Data for all of the entity IDs of my entity and then iterate through them. If I find an ID which is higher than the current temporary one, I make the temporary ID higher one higher than the aggregated one. When I'm done, I automatically have an ID which is higher than the highest one in the list. The only flaw I see with this is if there is a missing ID. (I believe that there is a simple fix for this as well.)
//
// Create a new entity description
//
NSEntityDescription *entity = [NSEntityDescription entityForName:#"MyEntity" inManagedObjectContext:self.managedObjectContext];
//
// Set the fetch request
//
NSFetchRequest *fetchRequest = [[[NSFetchRequest alloc] init] autorelease];
[fetchRequest setEntity:entity];
//
// We need to figure out how many
// existing groups there are so that
// we can set the proper ID.
//
// To do so, we use an aggregated request.
//
[fetchRequest setResultType:NSDictionaryResultType];
[fetchRequest setPropertiesToFetch:[NSArray arrayWithObject:#"entityID"]];
NSError *error = nil;
NSArray *existingIDs = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];
if (error != nil) {
//
// TODO: Handle error.
//
NSLog(#"Error: %#", [error localizedDescription]);
}
NSInteger newID = 0;
for (NSDictionary *dict in existingIDs) {
NSInteger IDToCompare = [[dict valueForKey:#"entityID"] integerValue];
if (IDToCompare >= newID) {
newID = IDToCompare + 1;
}
}
//
// Create the actual entity
//
MyEntity *newEntity = [[MyEntity alloc] initWithEntity:entity insertIntoManagedObjectContext:self.managedObjectContext];
//
// Set the ID of the new entity
//
[newEntity setEntityID:[NSNumber numberWithInteger:newID]];
//
// ... More Code ...
//
Accroding to your EDIT2 and Edit3, following answer will help you.. Assume your id field as NSNumber having unsignedInt as ID.
1) Fetch all records for corresponding entity.
NSError *error = nil;
NSArray *array = [self fetchAllFileEntity:&error];
2) Find maximum number belonging to that result.
NSNumber *maxValue = nil;
if (array)
maxValue = [array valueForKeyPath:#"#max.uniqueId.unsignedIntegerValue"];
else
maxValue = [NSNumber numberWithUnsignedInteger:0];
3) Assign maxValue+1 to your new entity
entity.uniqueId = [NSNumber numberWithUnsignedInteger:maxValue.unsignedIntegerValue+1];
I have come up with this solution for the said problem, hope it's gonna be helpful for some one.
AppDelegate *appdelegate = (AppDelegate *) [[UIApplication sharedApplication] delegate];
NSManagedObjectContext *context = [appdelegate managedObjectContext];
NSError *error = nil;
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *chatHist = [NSEntityDescription
entityForName:#"ChatHistory" inManagedObjectContext:context];
[fetchRequest setEntity:chatHist];
int chatIdNumber = 0;
NSArray *fetchedObjects = [context executeFetchRequest:fetchRequest error:&error];
if ([fetchedObjects count] > 0) {
ChatHistory *chatHistObj = [fetchedObjects objectAtIndex:[fetchedObjects count]-1];
chatIdNumber = [chatHistObj.chatId intValue];
}
chatIdNumber = chatIdNumber+1;
ChatHistory *chat_History = [NSEntityDescription insertNewObjectForEntityForName:#"ChatHistory" inManagedObjectContext:context];
chat_History.chatId = [NSString stringWithFormat:#"%d",chatIdNumber];
I have the following code, and I was wondering if theres any way to make this faster. Basically my app downloads some JSON (about 4000 records) from the net, and updates or creates my managed objects based on the data. At the moment it's quite slow, and I can see why, but I'm new to core data so I was wondering if there's anything I can do to make it faster?
NSFetchRequest *request = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Company" inManagedObjectContext:managedObjectContext];
[request setEntity:entity];
NSMutableArray *coreDataArray = [[managedObjectContext executeFetchRequest:request error:nil] mutableCopy];
[request release];
for (NSDictionary *dict in arr) {
NSArray *filtered = [coreDataArray filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:#"(code == %#)", [dict objectForKey:#"Code"]]];
//NSLog(#"COREDATA ARRAY: %d FILTERED ARRAY: %d CODE: %# COREDATA FIRST CODE: %#", [coreDataArray count], [filtered count], [dict objectForKey:#"Code"], [[coreDataArray objectAtIndex:0] code]);
if ([filtered count] > 0) {
Company *c = [filtered objectAtIndex:0];
if ([dict objectForKey:#"Defunct"]) {
NSLog(#"DELETED DEFUNCT COMPANY");
[managedObjectContext deleteObject:c];
} else {
[c populateWithJSONDictionary:dict];
}
} else {
Company *c = (Company *)[NSEntityDescription insertNewObjectForEntityForName:#"Company" inManagedObjectContext:managedObjectContext];
[c populateWithJSONDictionary:dict];
}
float percent = (float)[arr indexOfObject:dict]/[arr count];
[self performSelectorInBackground:#selector(updateProgressView:) withObject:[NSString stringWithFormat:#"%f",percent]];
}
[coreDataArray release];
Many thanks for any help you can give.
You should check out the Core Data Programming Guide: Performance section
It has some specific advice for data import performance.
In case Apple moves the documentation again, here is a good search query on Google site:developer.apple.com core data import performance
I have an iPhone app that has the needs to avoid inserting duplicate records, at first I thought I could just test each object in my in-memory array, create a fetch request for each object and test if it exists. But this is proving slow on the device, very slow (about 5 seconds, which is not acceptable).
I have been trying to piece together how to create some smart predicate that I could use in order to get this to work efficiently but without much success.
My objects have a NSNumber field that I have set as the "Identity Property" and also non-optional. This field is called sampleTime (again, this is NOT a date, but a NSNumber)
Here is my idea (borrowed from other threads and even some of my own questions of SO):
Obviously doing a fetch per object (around 380 objects) is not going to work for performance, so I was under the impression that I could do most of it in memory and it would be faster. I need to create some predicate that uses the IN clause, then iterate over that fetch result, testing if any one of the objects is inside that result set, if NOT then insert it, if SO then do nothing.
But my implementation is not working:
NSMutableArray *timeStampArray = [[NSMutableArray alloc] init];
for (id emTmp in myListOfObjects)
[timeStampArray addObject: [NSNumber numberWithInt:[[emTmp sampleTime] timeIntervalSince1970]]];
NSFetchRequest *fetch = [[[NSFetchRequest alloc] init] autorelease];
[fetch setEntity:[NSEntityDescription entityForName:#"ElectricalMeasurementEntity" inManagedObjectContext:context]];
[fetch setPredicate:[NSPredicate predicateWithFormat:#"sampleTime in %#", timeStampArray]];
NSArray *results = [context executeFetchRequest:fetch error:nil];
int resCount = [results count];
But resCount is always zero, and I dont know why...
BTW, myListOfObjects contains business objects which also have a sampleTime property which IS an NSDate type.
EDIT
Ok, update, I got the basics working. The reason why I was not getting any results was because the loop that created the array was using the id type, which when used the way I was using it was not creating NSNumber objects correctly.
Now I do this:
for (id emTmp in myListOfObjects)
{
Measurement *t = (Measurement*)emTmp;
NSTimeInterval d = [t.sampleTime timeIntervalSince1970];
[timeStampArray addObject: [NSNumber numberWithInt:[[t sampleTime] timeIntervalSince1970]]];
}
which creates a nice list which works very well.
However, I then go on to do this:
NSMutableArray *itemsToInsert = [[NSMutableArray alloc] init];
for (id em in myListOfObjects)
{
BOOL found = NO;
Measurement *t = (Measurement*)em;
for (id e in results) //results from Fetch Request which is now populated properly
{
MeasurementEntity *entity = (MeasurementEntity*)e;
if ([entity.sampleTime isEqualToNumber:[NSNumber numberWithInt:[[t sampleTime] timeIntervalSince1970]]])
{
found = YES;
break;
}
}
if (!found)
[itemsToInsert addObject: t];
}
This loop (for around 850 objects, on the iPhone 3Gs) takes around 10 - 12 seconds, which I can see why (when 850*850 = 722500 loops!). Can I be more efficient about this?
Thanks
You need to strip the fetch down such that it will only check the one property. Then do all your comparisons with predicates for speed. Something like this:
NSArray *newData=[NSArray arrayWithObjects:[NSNumber numberWithInt:1],[NSNumber numberWithInt:6],nil];
NSManagedObject *mo;
for (int i=0; i<5; i++) {
mo=[NSEntityDescription insertNewObjectForEntityForName:#"Test" inManagedObjectContext:self.moc];
[mo setValue:[NSNumber numberWithInt:i] forKey:#"numAttrib" ];
}
[self saveContext];
NSFetchRequest *fetch=[[NSFetchRequest alloc] init];
NSEntityDescription *testEntity=[NSEntityDescription entityForName:#"Test" inManagedObjectContext:self.moc];
[fetch setEntity:testEntity];
// fetch only the one property you need to test
NSDictionary *propDict=[testEntity propertiesByName];
[fetch setPropertiesToFetch:[NSArray arrayWithObject:[propDict valueForKey:#"numAttrib"]]];
// Return as dictionaries so you don't have the overhead of live objects
[fetch setResultType:NSDictionaryResultType];
// fetch only those existing property values that match the new data
NSPredicate *p=[NSPredicate predicateWithFormat:#"numAttrib in %#",newData];
[fetch setPredicate:p];
NSArray *fetchReturn=[self performFetch:fetch];//<-- my custom boilerplate
// extract the existing values from the dictionaries into an array
NSArray *values=[fetchReturn valueForKey:#"numAttrib"];
// filter out all new data values that already exist in Core Data
p=[NSPredicate predicateWithFormat:#"NOT (SELF in %#)",values];
NSArray *unmatchedValues=[newData filteredArrayUsingPredicate:p];
NSLog(#"unmatcheValues=%#",unmatchedValues);
... which outputs:
unmatcheValues=(
6
)
Now you only need to create new managed objects for the values returned. All other new values already exist.
This may seem an obvious suggestion, but if [context executeFetchRequest:fetch error:nil] is not returning any results, seems like the first thing to do is check for errors instead of ignoring them (by setting error:nil).
Something like:
NSError *error = nil;
NSArray *results = [context executeFetchRequest:fetch error:&error];
if (results == nil) { // fetch failed - huh?
NSLog(#"Fetch error %#, %#", error, [error userInfo]);
}