How do I display my Core Data values? - objective-c

Question

I have a basic UITableView where I can add items using Core Data as well as delete if needed.
Let's say I add 5 items to the UITableView. I want to also display these five items on another view, preferably a PDF.
What's the best approach to accomplish this?
I'm attempting using NSUserDefaults as well, but the only value that is appearing is the last value that is entered.
Here's some of the main code used. Any advice is appreciated!
This is from the UIViewController where I input the text:
-(NSManagedObjectContext * )managedObjectContext
{
return [(AppDelegate *) [[UIApplication sharedApplication] delegate] managedObjectContext];
}
-(void)saveButtonTapped:(id)sender
{
[self.managedObjectContext save:nil];
if (_majorTextField.text == nil)
{
_majorString = #"";
}
else
{
_majorString = [[NSString alloc] initWithFormat:#"%#", _majorTextField.text];
self.task.title = self.majorTextField.text;
NSUserDefaults * majorDefault = [NSUserDefaults standardUserDefaults];
[majorDefault setObject:_majorString forKey:#"major"];
}
[self.navigationController popViewControllerAnimated:YES];
}
Here is where I am adding the text on my PDF:
+(void)createPDF:(NSString*)filePath
{
// Create the PDF context using the default page size of 612 x 792.
UIGraphicsBeginPDFContextToFile(filePath, CGRectZero, nil);
// Mark the beginning of a new page.
UIGraphicsBeginPDFPageWithInfo(CGRectMake(0, 0, 612, 792), nil);
NSUserDefaults * majorDefault = [NSUserDefaults standardUserDefaults];
NSString * majorString = [majorDefault stringForKey:#"major"];
[PDFRenderer drawText:majorString inFrame:CGRectMake(35, 190, 300, 50) fontName:#"TimesNewRomanPSMT" fontSize:14];
UIGraphicsEndPDFContext();
}

Answer 1

You are saving your NSManagedObjectContext before you make changes to the represented object in your view controller. In saveButtonTapped: you save the context but only later set self.task.title ... Perhaps I'm missing something; but I think you want save the context after changing self.task.title.
In the other views that need to access the managed objects in question, you need to fetch them by constructing an NSFetchRequest and executing that request against an NSManagedObjectContext. I can't give any substantial example without knowing more about your model; but that's the basic idea.
Depending on your needs, Core Data may be ideal or it may be overkill. There's a lot to be gained by using Core Data for your object graph persistence technology - but there's a lot of subtlety. As Apple puts it. "Core Data is not an entry level technology." (Apple, "Getting Started with Core Data")
We're probably all guilty of this, but you should pass an error object in [self.managedObjectContext save:nil]; and handle the return value, thusly:
NSError *saveError = nil;
if( ![[self managedObjectContext] save:&saveError] ) {
// do something with saveError
}
EDIT:
Core Data is fine for what you describe in your comment. It's just a matter of understanding the underlying principles of persistent stores, managed object contexts, etc. What you do get with Core Data are a set of conveniences for displaying data in table views, i.e. NSFetchedResultsController.