Swift 3 - 向左滑动以使用 Array 更改标签

Question

我初学者学习Swift 3 - UIS滑动手势，但如果使用数组则无法工作。

这是我的代码。

如何编码，使标签仅从"hello1"更改为"hello2"，然后再次向左滑动到"hello3"。还可以反向滑动到从"hello3"到"hello2"和"hello1"。或循环回第一个。

谢谢。

class ChangeLabelViewController: UIViewController {
var helloArray = ["Hello1", "Hello2", "Hello3"]
var currentArrayIndex = 0

@IBOutlet weak var helloLabel: UILabel!

override func viewDidLoad() {
    super.viewDidLoad()
    let leftSwipe = UISwipeGestureRecognizer(target: self, action: #selector(ChangeLabelViewController.handleSwipes(sender:)))
    let rightSwipe = UISwipeGestureRecognizer(target: self, action: #selector(ChangeLabelViewController.handleSwipes(sender:)))
    leftSwipe.direction = .left
    rightSwipe.direction = .right
    view.addGestureRecognizer(leftSwipe)
    view.addGestureRecognizer(rightSwipe)
    helloLabel.text = helloArray[currentArrayIndex]
}
func handleSwipes(sender: UISwipeGestureRecognizer) {
    if sender.direction == .left {
        helloLabel.text = helloArray[currentArrayIndex + 1]

    }
    if sender.direction == .right {
    }
}

Answer 1

试试这个：

if sender.direction == .left {
    currentArrayIndex = (currentArrayIndex + 1) % 3
    helloLabel.text = helloArray[currentArrayIndex]
}
if sender.direction == .right {
    currentArrayIndex = (currentArrayIndex + 3 - 1) % 3 //if uInt
    helloLabel.text = helloArray[currentArrayIndex]
}

Answer 2

你也可以用下面的代码来做到这一点，

func handleSwipes(sender: UISwipeGestureRecognizer) {
    if sender.direction == .left {
        if(currentArrayIndex < helloArray.count - 1)
        {
            currentArrayIndex += 1
            let indexPath = IndexPath(item: currentArrayIndex, section: 0)
            helloLabel.text = helloArray[indexPath.row]
        }
    }
    if sender.direction == .right {
        if(currentArrayIndex > 0)
        {
            currentArrayIndex -= 1
            if currentArrayIndex == -1
            {
                currentArrayIndex = 0
                let indexPath = IndexPath(item: currentArrayIndex, section: 0)
                helloLabel.text = helloArray[indexPath.row]
            }
            else {
                let indexPath = IndexPath(item: currentArrayIndex, section: 0)
                helloLabel.text = helloArray[indexPath.row]
            }
        }
    }