Swift iOS - 如何将 UIPopoverBackgroundView Class 中的方法连接到不同 class 中的 PopoverController？

Question

我正在使用 PopoverController，我想去除背景阴影。 Apple 说要将 UIPopoverBackgroundView 和 return false 子类化为 override class var wantsDefaultContentAppearance: Bool { get }

https://developer.apple.com/documentation/uikit/uipopoverbackgroundview/1619357-wantsdefaultcontentappearance

我将它子类化并将布尔值设置为 false 但阴影仍然显示。如何将此子类连接到我在 LogoutClass 的 Actionsheet 中使用的 PopoverController？

UIPopoverBackgroundView 子类：

class PopoverBackgroundView: UIPopoverBackgroundView {

override class var wantsDefaultContentAppearance: Bool {
        get {
            return false
        }
    }
}

注销控制器：

class LogoutController:UIViewController{

fileprivate func logOff(){

let actionSheet = UIAlertController(title: nil, message: "Logging out?", preferredStyle: .actionSheet)

 let logout = UIAlertAction(title: "Log Out", style: .default){
            (action) in
//bla bla bla
}

actionSheet.addAction(logout)

if let popoverController = actionSheet.popoverPresentationController{
            popoverController.sourceView = view
            guard let window = UIApplication.shared.keyWindow else { return }
            window.backgroundColor = .clear
            popoverController.sourceRect = CGRect(x:window.bounds.midX, y:window.bounds.midY, width:0, height:0)
            popoverController.permittedArrowDirections = []

        }
present(actionSheet, animated: true, completion: nil)
}
}

Answer 1

您必须像这样设置 UIPopoverPresentationController 实例的 popoverBackgroundViewClass 属性 :

Objective C :

popoverController.popoverBackgroundViewClass = [PopoverBackgroundView class];

Swift

popoverController?.popoverBackgroundViewClass = PopoverBackgroundView.self

根据 Apple 文档：

The default value of this property is nil, which causes the presentation controller to use the default popover appearance. Setting this property to a value other than nil causes the presentation controller to use the specified class to draw the popover’s background content. The class you specify must be a subclass of UIPopoverBackgroundView .