How to make a designated initializer for NSManagedObject subclass in Swift?

Question

class Alternative: NSManagedObject {      @NSManaged var text: String     @NSManaged var isCorrect: Bool     @NSManaged var image: NSData }   convenience init(text: String, isCorrect: Bool, entity: NSEntityDescription, insertIntoManagedObjectContext context: NSManagedObjectContext!) {         let alternative = Alternative(entity: entity, insertIntoManagedObjectContext: context) as Alternative         alternative.text = text         alternative.isCorrect = isCorrect         return alternative } 

I want to make a method that lets me initialize new objects with this call:

let newAlternative = Alternative("third platform", True, entityDescription, managedObjectContext) 

But i get the error:

Convenience initializer for Alternative must delegate with self.init 

What do i need to change in my initalizer to make my example usage work?

Answer 1

A convenience initializer must call the designated initializer on self:

convenience init(text: String, isCorrect: Bool, entity: NSEntityDescription, insertIntoManagedObjectContext context: NSManagedObjectContext!) {     self.init(entity: entity, insertIntoManagedObjectContext: context)     self.text = text     self.isCorrect = isCorrect } 

which would be called as

let newAlternative = Alternative(text: "third platform", isCorrect: true,      entity: entityDescription, insertIntoManagedObjectContext: managedObjectContext) 

In addition, you could also move the creation of the entity description into the convenience initializer instead of passing it as an argument (as motivated by Mundi's answer):

convenience init(text: String, isCorrect: Bool, insertIntoManagedObjectContext context: NSManagedObjectContext!) {     let entity = NSEntityDescription.entityForName("Alternative", inManagedObjectContext: context)!     self.init(entity: entity, insertIntoManagedObjectContext: context)     self.text = text     self.isCorrect = isCorrect } 

Answer 2

I simply did this with a class function:

class func newInstance(text: String, notes:String,                      context: NSManagedObjectContext) -> Item {     var item = NSEntityDescription.insertNewObjectForEntityForName("Item",                 inManagedObjectContext: context) as Item     item.notes = notes     item.text = text     return item } 

which you can call like this (almost as pretty):

let item = Item.newInstance(text, notes:notes, context:context)