从UISwipeGestureRecognizer的功能更新阵列索引

Question

Label view shall display the next item (just as text string) from an array when it is swiped. So, I made index of array with initial value of 0 and referenced it within the function. However, when the label is swiped the index does not update. Would be great to understand how to update the index when swiped label. I also tried by putting index var within function, but it did not work either. Here is the code. Thanks.

   import UIKit

     class ViewController: UIViewController 
{
         @IBOutlet var result: UILabel!
         var index: Int = 0
         var items: [String]  = ["apple", "hammer", "cup"]
         let swipeRec = UISwipeGestureRecognizer()

         override func viewDidLoad() {
             super.viewDidLoad()

             swipeRec.addTarget(self, action: "swipedView")
             result.addGestureRecognizer(swipeRec)
             result.userInteractionEnabled = true
         }

          func swipedView () {
             result.text = "\(items[index])"
             index++
         } 
}

Answer 1

in viewDidLoad

    var leftSwipe = UISwipeGestureRecognizer(target: self, action: Selector("handleSwipes:"))
    var rightSwipe = UISwipeGestureRecognizer(target: self, action: Selector("handleSwipes:"))

    leftSwipe.direction = .Left
    rightSwipe.direction = .Right

    result.addGestureRecognizer(leftSwipe)
    result.addGestureRecognizer(rightSwipe) viewDidLoad
    result.userInteractionEnabled = true


func handleSwipes(sender:UISwipeGestureRecognizer) {
    if (sender.direction == .Left) {
        println("Swipe Left")
        if index > 0 { index -= 1}
    }

    if (sender.direction == .Right) {
        println("Swipe Right")
        if index < (items.count - 1) { index += 1}
    }

    println(items[index])
    result.text = items[index]

}

Answer 2

This is working for me. Tested on a real iPhone 4s.

@IBOutlet var result: UILabel!
var index: Int = 0
var items: [String]  = ["apple", "hammer", "cup"]

override func viewDidLoad() {
    super.viewDidLoad()

    var leftSwipe = UISwipeGestureRecognizer(target: self, action: "swipedView:")
    var rightSwipe = UISwipeGestureRecognizer(target: self, action: "swipedView:")

    leftSwipe.direction = .Left
    rightSwipe.direction = .Right

    result.addGestureRecognizer(leftSwipe)
    result.addGestureRecognizer(rightSwipe)

    result.userInteractionEnabled = true
    result.text = items[index]
}

func swipedView(sender:UISwipeGestureRecognizer!) {
    if (sender.direction == .Left) {
        println("Swipe left")
        if index > 0 {
            index -= 1
        }
    }

    if (sender.direction == .Right) {
        println("Swipe right")
        if index < (items.count - 1) {
            index += 1
        }
    }

    result.text = items[index]
}

As we are adding UISwipeGestureRecognizer to the result UILabel, make sure that the label has the necessary size to allow us to make the gesture and if you are swiping the label and not the background view. The solution provided by HMHero works for me too.

Hope that helps.

Answer 3

The original posted code did work for me. Just be sure to specify the direction you would like the user to use. The direction defaulted to a right swipe.