How to store an image in core data

Question

I'm new to iOS. I've been trying to make an application that will store an image captured from the camera into CoreData. I now know how to store data like NSStrings, NSDate and other type but struggling to store an image. I've read so many articles saying you must write it to the disk and write to a file, but I can't seem to understand it.

The following code is the one i used to store other data to core data.

- (IBAction)submitReportButton:(id)sender
{
    UrbanRangerAppDelegate *appDelegate = [[UIApplication sharedApplication] delegate];

    managedObjectContext = [appDelegate managedObjectContext];

    NSEntityDescription *entity = [NSEntityDescription entityForName:@"PotholesDB" inManagedObjectContext:appDelegate.managedObjectContext];
    NSManagedObject *newPothole = [[NSManagedObject alloc]initWithEntity:entity insertIntoManagedObjectContext:managedObjectContext];


    [newPothole setValue:self.relevantBody.text forKey:@"relevantBody"];
    [newPothole setValue:self.subjectReport.text forKey:@"subjectReport"];
    [newPothole setValue:self.detailReport.text forKey:@"detailReport"];
//    [newPothole setValue:self.imageView forKey:@"photo"];

    NSDate *now = [NSDate date];
    //NSLog(@"now : %@", now);
    NSString *strDate = [[NSString alloc] initWithFormat:@"%@", now];
    NSArray *arr = [strDate componentsSeparatedByString:@" "];
    NSString *str;
    str = [arr objectAtIndex:0];
    NSLog(@"now : %@", str);

    [newPothole setValue:now forKey:@"photoDate"];
    [newPothole setValue:self.latitudeLabel.text forKey:@"latitude"];
    [newPothole setValue:self.longitudeLabel.text forKey:@"longitude"];
    [newPothole setValue:self.addressLabel.text forKey:@"streetName"];
    [newPothole setValue:streeNameLocation forKey:@"location"];


    NSError *error;
    [managedObjectContext save:&error];

    UIAlertView *ll = [[UIAlertView alloc] initWithTitle:@"Saving" message:@"Saved data" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];

    [ll show];
} 

Answer 1

You can store images in Core Data using the Binary Data attribute type. However you should be aware of a few things:

• Always convert your UIImage to a portable data format like png or jpg For example:

  NSData *imageData = UIImagePNGRepresentation(image);

• Enable "Allows external storage" on this attribute Core Data will move the data to an external file if it hits a certain threshold. This file is also completely managed by Core Data, so you don't have to worry about it.

• If you run into performance issues, try moving the Binary Data attribute to a separate entity.

• You should abstract the conversion to NSData behind the interface of your NSManagedObject subclass, so you don't have to worry about conversions from UIImage to NSData or vice versa.

• If your images are not strongly related to the entities in your model, I would suggest storing them outside of Core Data.