Question

我有一系列图像，我希望能够向前（向左）滑动到下一个图像，或向后（向右）滑动到上一个图像。当imageList达到-1 /超出范围时，应用程序崩溃。我无法弄清楚如何将其保持在范围内的逻辑。

这是我的代码：

var imageList:[String] = ["image1.jpg", "image2.jpg", "image3.jpg"]
let maxImages = 2
var imageIndex: NSInteger = 1

滑动手势在我的viewDidLoad（）方法中，不确定这是否正确...：

    override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    var swipeRight = UISwipeGestureRecognizer(target: self, action: "swiped:") // put : at the end of method name
    swipeRight.direction = UISwipeGestureRecognizerDirection.Right
    self.view.addGestureRecognizer(swipeRight)

    var swipeLeft = UISwipeGestureRecognizer(target: self, action: "swiped:") // put : at the end of method name
    swipeLeft.direction = UISwipeGestureRecognizerDirection.Left
    self.view.addGestureRecognizer(swipeLeft)

    image.image = UIImage(named:"image1.jpg")

}


func swiped(gesture: UIGestureRecognizer) {

    if let swipeGesture = gesture as? UISwipeGestureRecognizer {

        switch swipeGesture.direction {

        case UISwipeGestureRecognizerDirection.Right :
            println("User swiped right")

        /*No clue how to make it go back to the previous image and 
        when it hits the last image in the array, it goes back to 
        the first image.. */

        case UISwipeGestureRecognizerDirection.Left:
            println("User swiped Left")


            if imageIndex > maxImages {

                imageIndex = 0

            }

            image.image = UIImage(named: imageList[imageIndex])

            imageIndex++



        default:
            break //stops the code/codes nothing.


        }

    }


}

提前多多感谢！

Answer 1

首先，您的图像索引应该设置为零，因为数组元素从零开始，但这不是您的问题的来源

var imageIndex: NSInteger = 0

然后您的刷卡功能应该如下

func swiped(gesture: UIGestureRecognizer) {

if let swipeGesture = gesture as? UISwipeGestureRecognizer {

    switch swipeGesture.direction {

    case UISwipeGestureRecognizerDirection.Right :
        println("User swiped right")

        // decrease index first

        imageIndex--

        // check if index is in range

        if imageIndex < 0 {

            imageIndex = maxImages

        }

       image.image = UIImage(named: imageList[imageIndex])

    case UISwipeGestureRecognizerDirection.Left:
        println("User swiped Left")

        // increase index first

        imageIndex++

        // check if index is in range

        if imageIndex > maxImages {

            imageIndex = 0

        }

       image.image = UIImage(named: imageList[imageIndex])




    default:
        break //stops the code/codes nothing.


    }

}


}

Answer 2

你可以做出类似的事情。

首先，你需要设置一个位置计数器，表示你现在所处的位置。重要提示：如果要从第一个元素开始，则需要将开始设置为0，因为数组从0开始计数：

var swipePosition = 0

然后，如果向前滑动，则需要检查当前的swipePosition是否大于图像数量。为此，您可以使用数组的count方法。但是你必须减1，因为位置从0开始。所以如果它已经在你的数组中的最高或最低位置，你不必做任何事情。否则，您可以添加或减去一个位置：

//swipe forward
if swipePosition > imageList.count-1{
    //do nothing because it is already at the highest position
}else{
    swipePosition += 1
}

image.image = UIImage(named: imageList[swipePosition])

//swipe backward

if swipePosition == 0 {
    //Do nothing because it is already at start.
}else{
    swipePosition -= 1
}

image.image = UIImage(named: imageList[swipePosition])

Answer 3

`

And heroku works fine in other network connection.

Answer 4

@IBOutlet weak var imageView: UIImageView!
    var imageIndex:NSInteger = 0
    var maximages = 3
    var imageList: [String] = ["burger", "burger2", "burger3", "burger4"]

    override func viewDidLoad() {
        super.viewDidLoad()

        let swipeRight = UISwipeGestureRecognizer(target: self, action: #selector(swiped)) // put : at the end of method name
        swipeRight.direction = UISwipeGestureRecognizerDirection.right
        self.view.addGestureRecognizer(swipeRight)

        let swipeLeft = UISwipeGestureRecognizer(target: self, action: #selector(swiped)) // put : at the end of method name
        swipeLeft.direction = UISwipeGestureRecognizerDirection.left
        self.view.addGestureRecognizer(swipeLeft)

        imageView.image = UIImage(named:"burger")
    }

    func swiped(gesture: UIGestureRecognizer) {

        if let swipeGesture = gesture as? UISwipeGestureRecognizer {

            switch swipeGesture.direction {

                case UISwipeGestureRecognizerDirection.right :
                    print("User swiped right")

                    // decrease index first

                    imageIndex -= 1

                    // check if index is in range

                    if imageIndex < 0 {

                        imageIndex = maximages
                    }

                    imageView.image = UIImage(named: imageList[imageIndex])

                case UISwipeGestureRecognizerDirection.left:
                    print("User swiped Left")

                    // increase index first

                    imageIndex += 1

                    // check if index is in range

                    if imageIndex > maximages {

                        imageIndex = 0
                    }

                    imageView.image = UIImage(named: imageList[imageIndex])

                default:
                    break //stops the code/codes nothing.
                }
            }
        }
}

在Swift图像阵列中来回滑动

4 个答案: