未调用 UISheetPresentationControllerDelegate 方法

问题描述

问题

我在 UISheetPresentationController 中尝试了 Xcode13.0 beta 示例。

并且为了处理detent change事件，我实现了sheetPresentationConstructionSelectedDetentIdentifier(_:)方法，但是拖动改变大小时不会调用这个方法。

这是 Xcode beta 中的错误吗？或者我的实现有什么问题吗？

这是我的代码

class ModalViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        if let presentationController = presentationController as? UISheetPresentationController {
            presentationController.detents = [.medium(),.large()]
            presentationController.delegate = self
        }        
    }
}

extension ModalViewController: UISheetPresentationControllerDelegate {

    func sheetPresentationControllerDidChangeSelectedDetentIdentifier(_ sheetPresentationController: UISheetPresentationController) {
        /// not called
    }
}

解决方法

以这种方式配置它并检查它现在是否适合您：

class ViewController: UIViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
    }
    
    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        
        let controller = SecondController()
        controller.transitioningDelegate = self
        controller.modalPresentationStyle = .custom
        self.present(controller,animated: true)
    }
}

extension ViewController: UIViewControllerTransitioningDelegate {
    func presentationController(forPresented presented: UIViewController,presenting: UIViewController?,source: UIViewController) -> UIPresentationController? {
        let controller = UISheetPresentationController(presentedViewController: presented,presenting: presenting)
        controller.detents = [.medium(),.large()]
        controller.delegate = self
        return controller
    }
}

extension ViewController: UISheetPresentationControllerDelegate {
    func sheetPresentationControllerDidChangeSelectedDetentIdentifier(_ sheetPresentationController: UISheetPresentationController) {
        print("Did Change Called!!!")
    }
}

class SecondController: UIViewController,UIViewControllerTransitioningDelegate {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        self.view.backgroundColor = UIColor.blue
    }
}