How to avoid creating a copy of an array of objects in swift

I have a dictionary of arrays that contain one kind of objects : database records. Each array is like a table associated to a key (table name) in the dictionary.

My issue is: How do I update a table (delete a record, add a record, etc) without making any temporary copy of the table, like I would do with an NSDictionary of NSArrays ?

Currently, I do :

func addRecord(theRecord: DatabaseRecord, inTable tableName: String)
{
    if var table = self.database[tableName]
    {
        table.append(theRecord)
        self.database[tableName] = table
    }
    else
    {
        self.database[tableName] = [theRecord];
    }
}

The issue is: a temporary copy of the table is made twice. This is pretty inefficient.

via Chebli Mohamed