Problems with keyboard functions?

Question

I am having some trouble with the return key on the keyboard executing code. I have tried in the past and the following code worked perfectly fine:

func textFieldShouldReturn(textField: UITextField) -> Bool{
    textField.resignFirstResponder()
    valueOfLetter()
    return true;
}

But, for some reason, there is an error on the line valueOfLetter.

Here is the entire file in case it is necessary:

class ViewController: UIViewController {

override func viewDidLoad() {
    super.viewDidLoad()
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
}

@IBOutlet weak var strWordValue: UILabel!
@IBOutlet weak var strInputField: UITextField!


func textFieldShouldReturn(textField: UITextField) -> Bool{
    textField.resignFirstResponder()
    valueOfLetter()
    return true;
}

 var TextField: UITextField!

    func valueOfLetter(inputLetter: String) -> Int {
        let alphabet = ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", "w", "x", "y", "z"]

        for (index, letter) in alphabet {
            if letter = inputLetter.lowercaseString {
                return index + 1

                for character in word {
                    score += valueOfLetter(character)
                }
            }
        }

        return 0
    }
}

The error is: "missing argument in parameter #1 in call

The is another error on the line for (index, letter) in alphabet which says: 'String' not convertible to '([String, String])'

I am unsure of what these errors mean or how to fix them.

Any input or suggestions would be greatly appreciated.

Thanks in advance.

kellanburket · Answer 1 · 2015-03-14T18:16:39.553

Your method valueOfLetter takes a parameter, you need to call it with a parameter or it won't work. For instance:

 valueOfLetter("x")

Your second error is occurring because you're using a syntactic structure used to iterate over a dictionary with an array. Use the built-in enumerate function to iterate over an array with index values:

   for (index, letter) in enumerate(alphabet) {
        if letter = inputLetter.lowercaseString {
            return index + 1

            for character in word {
                score += valueOfLetter(character)
            }
        }
    }

Erik · Accepted Answer · 2015-03-15T21:56:32.713

The error message is because your [String] array cannot be fast-enumerated as a pair of indices and values. To do so, you need to use the enumerate function like mentioned above.

I would recommend promoting your alphabet array to a global or member variable. You can mark it as private so that it is not visible outside that source file.

// A through Z
private let alphabet = ["A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"]

You can use two functions to compute the score for a word. The first function will calculate the number of points for a specific letter. The second function will take a string and enumerate through it, summing up the point values for each letter.

func valueOfLetter(letter: Character) -> Int
{
    let letterString = String(letter).uppercaseString
    let index = find(alphabet, letterString)

    return index != nil ? index! + 1 : 0
}

func scoreForWord(word: String) -> Int
{
    let characters = Array(word)
    return characters.reduce(0) { sum, letter in sum + valueOfLetter(letter) }
}

I know this is a bit different than your initial setup. I just wanted to point out how useful the built-in Swift library functions are. Namely filter, map, and reduce.

EDIT: Here is how you can use each method via UITextFieldDelegate:

// This will be called every time the text changes in the UITextField
func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool
{
    let currentWord = textField.text as NSString
    let newWord = currentWord.stringByReplacingCharactersInRange(range, withString: string)

    let score = scoreForWord(newWord)

    // Do something with the score here

    return true
}

// This will be called when the return key is pressed
func textFieldShouldReturn(textField: UITextField) -> Bool
{
    let word = textField.text
    let score = scoreForWord(word)

    // Do something with the score here

    return true
}

These functions are part of your `ViewController`, you can call them when you need via `UITextFieldDelegate`, depending on your implementation. For example, if you wanted to display the score in real-time (as user types), you could use the `textField:shouldChangeCharactersInRange:replacementString:` delegate method. If you wanted it on return key, `textFieldShouldReturn:` delegate method. I'll update the post to reflect either. — Erik, Mar 15 '15 at 21:44

Problems with keyboard functions?

2 Answers2