Xcode 8.3, Swift 3.1 - Using common SQLite database as persistent container.

AppDelegate.swift

    lazy var persistentContainer: NSPersistentContainer = {
        
        let sqlitePath = Bundle.main.url(forResource: "DATABASE_NAME", withExtension: "sqlite")
        
        if FileManager.default.fileExists(atPath: sqlitePath!.path) {
            
            let container = NSPersistentContainer(name: "DATABASE_NAME")
            
            let description = NSPersistentStoreDescription(url: sqlitePath!)
            description.shouldInferMappingModelAutomatically = true
            description.shouldMigrateStoreAutomatically = true
            container.persistentStoreDescriptions = [description]
            
            container.loadPersistentStores(completionHandler: { (storeDescription, error) in
                if let error = error as NSError? {
                    
                    fatalError("Unresolved error \(error), \(error.userInfo)")
                }
            })
            return container
        }
        
        let container = NSPersistentContainer(name: "DATABASE_NAME")
         
         
        container.loadPersistentStores(completionHandler: { (storeDescription, error) in
            if let error = error as NSError? {
         
                fatalError("Unresolved error \(error), \(error.userInfo)")
            }
        })
        return container
    }()