App Hangs when saving in core data - swift

Question

I'm using swift core data to save user's info within the app but when its saving current users data (name,bio, 3-4 photos) it hangs for 2-3 seconds until it saves the data. What is the best way to avoid this hanging of the app? this is the code I'm using
for photo in photos {
let data = NSData(contentsOfURL: NSURL(string: photo.url!)!)
let newimg = UIImage(data: data!)
newusersImages.addObject(newimg!)
}
mayBeUser.name = currentuser!.objectForKey("name") as! String
let arrayData = NSKeyedArchiver.archivedDataWithRootObject(newusersImages)
let locationData = NSKeyedArchiver.archivedDataWithRootObject(currentuser!.objectForKey("location")!)
mayBeUser.photos = arrayData
mayBeUser.location = locationData
mayBeUser.about = currentuser!.objectForKey("about") as! String
mayBeUser.setValue(currentuser!.objectForKey("age") as! Int, forKey: "age")
mayBeUser.objectId = currentuser!.objectId!
mayBeUser.lastSeen = currentuser!.objectForKey("lastSeen") as! NSDate
try! context.save()
print("Current User Updated")
when the user has 10-15 friends , it takes hangs for a minute to save/update all the info/data of the users.

Answer 1

Here's how I'd do it. Now obviously you don't want the UI to hang, so you'll want to use a managed object context that has a private queue concurrency type. More info on that here. Specifically, look at the part at the end where he details how to create the export function.
Now, since you're saving data to the persistent store in this case, you might not want the user to go around changing stuff while their previous changes are being saved, in this case you might want an interim screen showing the progress of the save.

Answer 2

You (and your app) are having to work hard to save all that photo data into one attribute of your User entity. Instead, restructure your data model:
Create a separate Photo entity for the photos.
Don't store the photo image data in CoreData - just store a string with the URL.
Add a to-many relationship from User to Photo, instead of the photos attribute.
Incidentally, I would avoid using objectId as an attribute name: it's so close to CoreData's objectID it will cause confusion.