swift - 在这种情况下，如何重用 UIPickerView 中的 View ？

Question

似乎很多人只是返回一个 UILabel，但在我的例子中，我是在 View 中添加一个标签。观点永远不是零。这是 UIPickerView 的另一种用法，因为我将其组件旋转 90 度并让它横向滚动而不是上下滚动。

func pickerView(_ pickerView: UIPickerView, viewForRow row: Int, forComponent component: Int, reusing view: UIView?) -> UIView {

    if view == nil {

        let customWidth = 300
        let customHeight = 300

        let view = UIView(frame: CGRect(x:0, y:0, width:customWidth, height:customHeight))

        let label = UILabel(frame:CGRect(x:0, y:0, width:customWidth, height:customHeight))
        if let filter = filters.first(where: {$0.pickerViewRowIndex == row}) {
            var leading = ""
            if appPurchased == false && filter.requiresPurchase == true { leading = "🔒" }
            label.text = "\(leading)\(filter.nameStr)"
        }
        label.textColor = UIColor.black 
        label.font = UIFont(name:"HelveticaNeue-Bold", size: 18.0)
        label.textAlignment = .center

        view.addSubview(label)

        view.transform = CGAffineTransform(rotationAngle: 90 * (.pi/180))
        label.layer.masksToBounds = false

        return view

    }else{
        print("not nil") // console never prints this line
    }

    guard let reusedView = view else {
        assertionFailure("pickerView label view container never set")
        return view!
    }

    return reusedView
}

Answer 1

The view is never not nil.

正确。文档是错误的。实际上，在选取器 View viewForRow 中不存在重用 View 这样的事情。您总是需要创建一个新 View 并将其返回。