Iphone Core Data crashing on Save
I'm currently writing an Iphone application using Core Data and I get a EXC_BAD_ACCESS error during the [managedObjectContext save:&&error] code line. This crash only happens after I modify certain fields. More specifically my entity has two string fields (out of about 10 fields), that get their values from a the return of a modal view controller (like a text editor). The crash also only happens after these fields are edited, the first time I put a value in it works fine.
The reason I have string with format constructors with just strings is because I was trying to copy construct... not sure if that happens automatically? Thought maybe retain/release messages from those strings (those two are from the modal view controller), were getting released on dismissal of the modal view controller or something. Guess not though because it still doesn't work.
Here's the code section that is crashing:
[EDITED]
- (void)actionSheet:(UIActionSheet *)modalView clickedButtonAtIndex: (NSInteger)buttonIndex
switch(buttonIndex) {
case 0: {
if(message == nil) {
message = [NSEntityDescription insertNewObjectForEntityForName:@"MailMessage" inManagedObjectContext:self.managedObjectContext];
}
message.toString = txtTo.text;
message.fromString = txtFrom.text;
message.subjectString = txtSubject.text;
message.backgroundColor = [NSNumber numberWithInt:[bgColor intValue]];
message.textArray = [NSString stringWithFormat:@"%@", stringTextArray];
message.htmlString = [NSString stringWithFormat:@"%@", stringHTML];
message.timeStamp = [NSDate date];
message.statusCode = [NSNumber numberWithInt:0];
NSError *error = nil;
if (![message.managedObjectContext save:&error]) {
abort();
}
break;
}
case 1: {
break;
}
}
if(buttonIndex != modalView.cancelButtonIndex) {
[webViewBody loadHTMLString:@"<html><head></head><body></body></html>" baseURL:[NSURL URLWithString:@""]];
[self.navigationController popToRootViewControllerAnimated:YES];
}
}
And here's the crash log:
Exception Type: EXC_BAD_ACCESS (SIGBUS) Exception Codes: KERN_PROTECTION_FAILURE at 0x00000015 Crashed Thread: 0 Thread 0 Crashed: 0 libobjc.A.dylib 0x30011940 objc_msgSend + 20 1 CoreData 0x367f7d3e -[NSKnownKeysDictionary1 dealloc] + 82 2 CoreData 0x367f7cda -[NSKnownKeysDictionary1 release] + 34 3 CoreData 0x3687eec4 -[NSManagedObject(_NSInternalMethods) _setOriginalSnapshot__:] + 40 4 CoreData 0x36821030 -[NSManagedObjectContext(_NSInternalAdditions) _clearOriginalSnapshotAndInitializeRec:] + 16 5 CoreData 0x368205f2 -[NSManagedObjectContext(_NSInternalAdditions) _didSaveChanges] + 958 6 CoreData 0x368133bc -[NSManagedObjectContext save:] + 412 7 Decome 0x0001fdd6 -[CreateMessageViewController actionSheet:clickedButtonAtIndex:] (CreateMessageViewController.m:163) 8 UIKit 0x30a6cbd8 -[UIActionSheet(Private) _buttonClicked:] + 256 9 CoreFoundation 0x30256dd4 -[NSObject performSelector:withObject:withObject:] + 20 10 UIKit 0x3096e0d0 -[UIApplication sendAction:to:from:forEvent:] + 128 11 UIKit 0x3096e038 -[UIApplication sendAction:toTarget:fromSender:forEvent:] + 32 12 UIKit 0x3096e000 -[UIControl sendAction:to:forEvent:] + 44 13 UIKit 0x3096dc58 -[UIControl(Internal) _sendActionsForEvents:withEvent:] + 528 14 UIKit 0x309a6e9c -[UIControl touchesEnded:withEvent:] + 452 15 UIKit 0x309a60d4 -[UIWindow _sendTouchesForEvent:] + 520 16 UIKit 0x309a5464 -[UIWindow sendEvent:] + 108 17 UIKit 0x30936e3c -[UIApplication sendEvent:] + 400
Any help is appreciated, Thanks.
UPDATE: Also, even though the program crashes, when I open it back up it the data has saved correctly. So the EXC_BAD_ACCESS must happen after the save has gotten at least far enough to store in the persistent store i think.
If I comment out the save line, the code runs fine now. But it doesn't save after i close and exit. If I run the save line in my Root View Controllers willAppear function, it throws the same EXC_BAD_ACCESS error. The console doesn't say anything other than EXC_BAD_ACCESS if I do a backtrace I get :
#0 0x30011940 in objc_msgSend () #1 0x367f7d44 in -[NSKnownKeysDictionary1 dealloc] () #2 0x367f7ce0 in -[NSKnownKeysDictionary1 release] () #3 0x3687eeca in -[NSManagedObject(_NSInternalMethods) _setOriginalSnapshot__:] () #4 0x36821036 in -[NSManagedObjectContext(_NSInternalAdditions) _clearOriginalSnapshotAndInitializeRec:] () #5 0x368205f8 in -[NSManagedObjectContext(_NSInternalAdditions) _didSaveChanges] () #6 0x368133c2 in -[NSManagedObjectContext save:] () #7 0x0000314e in -[RootViewController viewWillAppear:] (self=0x11b560, _cmd=0x3014ecac, animated=1 '\001') at /Users/inckbmj/Desktop/iphone/Decome/Classes/RootViewController.m:85
Sorry the code wasn't properly formatted before. When this view controller gets created if it is not a new "message" it is passed a message object obtained from a fetchedResultsController like so:
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
MailMessage *aMessage = (MailMessage *)[fetchedResultsController objectAtIndexPath:indexPath];
[messageView loadMessage:aMessage viewOnly:NO usingTemplate:NO];
messageView.managedObjectContext = self.managedObjectContext;
[self.navigationController pushViewController:messageView animated:YES];
}
(the first set of code is from the MessageViewController.m file which is the class that messsageView is)
It only crashes if I present my EditorViewController as a modal view and then return. Even if I change the textArray and htmlString lines (which are the only things the modal view affects) to:
message.textArray = @"HELLO";
message.htmlString = @"HELLO";
it still crashes. If I comment both lines out however it doesn't crash.
So it seems like it crashes if I present a modal view and then try to edit either the textArray or htmlString fields of my NSOManagedObject...
Here is where i present the view:
- (void) touchesEnded: (NSSet *) touches withEvent: (UIEvent *) event {
if(!viewOnly) {
UITouch *touch = [touches anyObject];
CGPoint location = [touch locationInView: txtTo];
location = [touch locationInView: webViewBody];
if(CGRectContainsPoint(webViewBody.bounds, location)) {
[editor loadTextArrayString:stringTextArray];
[self presentModalViewController:editor animated:YES];
}
}
}
and where i dismiss it:
-(void)returnWithTextArray:(NSString *)arrayString HTML:(NSString *)html bgColor:(NSNumber *)numColor {
[self dismissModalViewControllerAnimated:YES];
self.stringTextArray = [NSString stringWithFormat:@"%@", arrayString];
self.stringHTML = [NSString stringWithFormat:@"%@", html];
self.bgColor = [NSNumber numberWithInt:[numColor intValue]];
[webViewBody loadHTMLString:self.stringHTML baseURL:[NSURL URLWithString:@""]];
}
Answer
You are only guaranteed to retain access to a managed object from the context as long as a change is pending to that object (insert, update, delete). As soon as you make a call to save:, you can lose your reference to the managed object.
While you stopped getting the error when you set setRetainsRegisteredObjects:YES, you may have introduced a memory management issue, as you are setting the managed object's lifetime to be dependent on the lifetime of the managed object context. If you're passing your context around throughout your app, this could get rather large if you have a large object hierarchy.
You can read more in the Apple docs here: http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/CoreData/Articles/cdMemory.html.