Core Data Primary Key

Question

This may seem stupid, but I still couldn\'t figure out how to mark a attribute as a primary key in the xcdatamodel file. My persistent storage is sqlite file. Can anyone hel

Answer 1

A Swift Extension to retrieve the primary key

extension NSManagedObject {
    var primaryKey : String {
        guard objectID.uriRepresentation().lastPathComponent.count > 1 else { return "" }
        return objectID.uriRepresentation().lastPathComponent.substring(from: 1)
    }
}

And for String

extension String
{
    func substring(from : Int) -> String {
        guard self.count > from else { return "" }
        return String(self[self.index(self.startIndex, offsetBy: from)...])
     }
}