different ways to unwrap optional

swift.optional.map.interviewFollowUp

func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCellWithIdentifier("cell", forIndexPath: indexPath) as! LineTableViewCell
        let eachLine = subwayDataStore.subwayArrayList[indexPath.row]
Optional option 1 : 
        if let iconName = eachLine.letter {
        cell.iconLabel.image = UIImage(named:iconName.lowercaseString)
        }
Optional option 2 : 
        let imageName = eachLine.letter.map {_ in 
             eachLine.letter!.lowercaseString
            }
        cell.iconLabel.image = UIImage(named:imageName!)
Optional option 3: 
        let image = eachLine.letter.map {
            UIImage(named: $0)
        }
        cell.iconLabel.image = image!
        cell.nameLabel.text = eachLine.name
        cell.descLabel.text = eachLine.desc
        return cell
    }

For option 2, No forced un-wrap needed in the map function (value is passed in unwrapped already)

    let imageName = eachLine.letter.map { (letter: String) in 
        return letter.lowercaseString
    }
    cell.iconLabel.image = UIImage(named:imageName!)

Or, possibly better, avoiding all forced unwrapping by putting the setter right in the map

_ = eachLine.letter.map { (letter: String) in
    cell.iconLabel.image = UIImage(named: letter.lowercaseString)
}

Of course then the compiler will force you to acknowledge that the map result is garbage (with _ =). So the ultimate solution might for cell.iconLabel.image itself to be Optional, such that this beauty would work:

cell.iconLabel.image  = eachLine.letter.map { (letter: String) in
    return UIImage(named: letter.lowercaseString)
}

That is the most functionally idiomatic way to write it.

Option 3 is nice :)