Question

我有一个自定义的UITableViewCell类，它的init方法如下所示：

init(style: UITableViewCellStyle, reuseIdentifier: String!) {
        super.init(style: style, reuseIdentifier: reuseIdentifier)

        let swipeLeft: UISwipeGestureRecognizer = UISwipeGestureRecognizer(target: self, action: "swipedLeft")
        let swipeRight: UISwipeGestureRecognizer = UISwipeGestureRecognizer(target: self, action: "swipedRight")

        swipeLeft.direction = UISwipeGestureRecognizerDirection.Left
        swipeRight.direction = UISwipeGestureRecognizerDirection.Right

        self.topLayerView?.addGestureRecognizer(swipeLeft)
        self.topLayerView?.addGestureRecognizer(swipeRight)
    }

self.topLayerView是一个IBOutlet。问题是当我添加gestureRecognizers时self.topLayerView为nil。

如果我在init方法中写出类似的内容：

if self.topLayerView? {
            println("NOT empty")
        } else {
            println("empty")
        }

它总是让我“空虚”。所以，我的问题是：将代码放在哪里是恰当的？

非常感谢任何帮助！

Answer 1

初始化在视图的生命周期中太早，以至于期望已经设置了任何IBOutlet。我建议将代码移动到单元格的awakeFromNib（）方法，该方法在接口文件完全加载后调用。您可以在NSObject UIKit Additions Reference中找到有关此方法和其他方法的更多信息。

override func awakeFromNib() {
    super.awakeFromNib()

    let swipeLeft: UISwipeGestureRecognizer = UISwipeGestureRecognizer(target: self, action: "swipedLeft")
    let swipeRight: UISwipeGestureRecognizer = UISwipeGestureRecognizer(target: self, action: "swipedRight")

    swipeLeft.direction = UISwipeGestureRecognizerDirection.Left
    swipeRight.direction = UISwipeGestureRecognizerDirection.Right

    self.topLayerView?.addGestureRecognizer(swipeLeft)
    self.topLayerView?.addGestureRecognizer(swipeRight)
}

在UITableViewCell自定义类的UIView属性上添加UISwipeGestureRecognizer

1 个答案: