Question

似乎很多人只是返回UILabel，但就我而言，我正在向视图添加标签。视图永远不会为零。这与UIPickerView的用法不同，因为我将其组件旋转了90度，并使其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

视图永远不会为零。

正确。该文档是错误的。实际上，没有像在选择器视图<xsl:text>\page Table of Contents\line</xsl:text> <xsl:text>{\field{\*\fldinst {\\TOC \\f \\h}}}</xsl:text>中重用视图那样的事情。您始终需要创建一个新视图并返回它。

在这种情况下，如何在UIPickerView内部重用视图？

1 个答案: