Could not cast value of type '__NSCFString' (0x103c93c50) to 'NSNumber' (0x103535b88). Error

I created an SQLite table with a row of id integer PRIMARY KEY. I used this tutorial to integrate SQLite with my app. I'm trying to add that to an array of Ints. Here's my code:

let all = "select id from \(self.tableName)"
let fullArray = self.dbManager.loadDataFromDB(all)

for currentObject in fullArray {  
    println(currentObject[0])
    println(_stdlib_getDemangledTypeName(currentObject[0]))
    self.tableViewData.append(currentObject[0] as! Int) //tableViewData is an array of Ints
}

Results of println statements:

2
Swift.ImplicitlyUnwrappedOptional

When I run the app, I get the following error at the last line of the code.

Could not cast value of type '__NSCFString' (0x103c93c50) to 'NSNumber' (0x103535b88).

What am I doing wrong, and how can I fix it?