xcode-重构开关有几种情况。

Question

So basically I want to create a keyboard and when the user click on a letter something should happen:

 @IBAction func letterBtn(sender: UIButton) { // All the letter buttons are linked to this func.

        switch sender.currentTitle! {

        case "A":
            moveLetters(sender)
        case "B":
            moveLetters(sender)
        case "C":
            moveLetters(sender)
        case "D":
            moveLetters(sender)
        case "E":
            moveLetters(sender)
        case "F":
            moveLetters(sender)
        case "G":
            moveLetters(sender)


        default :

            println("Error")
        }

    }
func animateLetter (pos: UILabel, btn: UIButton) { // Make the letter move towards a label.

        UIView.animateWithDuration(0.5, animations: { () -> Void in

            btn.center = pos.center
        })
    }

    func moveLetters (btn: UIButton) { // Determine which label the pressed letter should move towards.

        switch emptyPos.count {

        case 1:

            animateLetter(pos1, btn: btn)
            emptyPos.append(0)

        case 2:

            animateLetter(pos2, btn: btn)
            emptyPos.append(0)

        case 3:

            animateLetter(pos3, btn: btn)
            emptyPos.append(0)

        case 4:

            animateLetter(pos4, btn: btn)
            emptyPos.append(0)



        default:
            println("Error")
        }
    }

I found myself using multiple switch cases that basically do the same thing in 2 different functions, and I was wondering if there a better way than using 26 cases for the entire alphabet, and also for my other function.

Answer 1

First of all, you can combine cases:

switch sender.currentTitle! {
case "A", "B", "C": ... etc
    // do something

Second, the switch statement allows intervals , from which you could profit by looking at the first character of the button title:

switch sender.currentTitle![0] {
case "A"..."Z":
    // do something
}

As for your other question, I'd give each label a tag (pos1.tag = 1, pos2.tag = 2) etc. and use the viewWithTag function to get the right label.

Answer 2

@Glorfindel answer with "A"..."Z" range is nice. You can also use NSRegularExpression to do so:

let regex = try! NSRegularExpression(pattern: "^[A-Z]", options: .CaseInsensitive)
let range = NSMakeRange(0, distance(str.startIndex, str.endIndex))
if let match = regex.firstMatchInString(str, options: .ReportCompletion, range: range) {
    // Do something
}