I'm optimising my first iOS app before it hits the store, and noting methods which take seemingly larger amounts of time. I have a fairly simple master-detail app where entities from the Core Data SQLite are shown in a UITableView, then tapping one brings up a detail view where the user can mark it as a favorite (setting a BOOL flag in that object to YES. As soon as they hit their Favorite button, I call [NSManagedObjectContext save] to ensure their changes are reflected immediately, and in case of an unscheduled terminate, etc.
This save operation is currently taking around 205ms when testing on my iPhone 4S. There are around 4,500 entries in the database, each with a few strings, and a few boolean values (wrapped in NSNumbers).
First question: should it take 200ms to make this change? I'm only setting one boolean value, then saving the context, but I've never used Core Data before so I don't know if this is about normal.
Second question: the code I'm using is below – am I doing something wrong in the code to make the method take this long to execute?
- (IBAction) makeFavorite: (id) sender
{
[self.delegate detailViewControllerDidMakeFavorite];
[_selectedLine setIsLiked: [NSNumber numberWithBool: YES]];
[_selectedLine setIsDisliked: [NSNumber numberWithBool: NO]];
NSError *error;
if (![[[CDManager sharedManager] managedObjectContext] save:&error]) NSLog(@"Saving changes failed: %@, %@", error, [error userInfo]);
}
Perhaps I'm worrying over nothing (I am still a relatively new programmer), but on a wider note, 200ms is enough for me to at least try to address this issue, right? :)
Consider UIManagedDocument. It automatically handles saving in a background context. I especially recommend it if you are on iOS 6. If you are not passing object IDs around, or merging with other contexts, then you should be able to use it fairly easily and reliably.
Your simple use case seems tailor made for it.