ios - Swift/iOS Controller 在传递给函数时不保留委托(delegate)

Question

我有一个名为 LogbookFormTVC 的 UITableViewController 子类，它符合 UIPopoverPresentationControllerDelegate。在这个类中，我有一个创建和显示弹出窗口的函数:

// --------------------
// LogbookFormTVC.swift
// --------------------
class LogbookFormTVC: UITableViewController, UIAdaptivePresentationControllerDelegate, UIPopoverPresentationControllerDelegate {

  @IBAction func tapShowPopover(sender: AnyObject) {
    //Tap to show the popover
    self.presentViewController(showAircraftPicker(), animated: true, completion: nil)
  } 

  //Build the popover
  func showAircraftPicker() -> UIViewController{
    //Set up modal
    let storyboard = UIStoryboard(name: "Popovers", bundle: nil)
    var aircraftModal = storyboard.instantiateViewControllerWithIdentifier("AircraftModal") as! AircraftPickerVC
    let pc = aircraftModal.popoverPresentationController
    pc?.sourceView = self.view    
    pc?.delegate = self

    return aircraftModal
  }
}

我想移动这个 showAircraftPicker() 函数并使其在我的应用程序中的任何位置可用，所以我将它移动到另一个文件，如下所示:

// --------------------
// SomeWhereElse.swift
// --------------------

//This works
func showAircraftPicker(controller: LogbookFormTVC) -> UIViewController{
  //Set up modal
  let storyboard = UIStoryboard(name: "Popovers", bundle: nil)
  var aircraftModal = storyboard.instantiateViewControllerWithIdentifier("AircraftModal") as! AircraftPickerVC
  let pc = aircraftModal.popoverPresentationController
  pc?.sourceView = self.view    
  pc?.delegate = self

  return aircraftModal
}

请注意我必须如何将 controller 的类型设置为 LogbookFormTVC 以使其协议(protocol)符合性。但我希望此函数适用于任何类(当然，它符合正确的协议(protocol))。

所以这样做是行不通的:

func showAircraftPicker(controller: AnyObject) -> UIViewController{
  //Set up modal
  let storyboard = UIStoryboard(name: "Popovers", bundle: nil)
  var aircraftModal = storyboard.instantiateViewControllerWithIdentifier("AircraftModal") as! AircraftPickerVC
  let pc = aircraftModal.popoverPresentationController
  pc?.sourceView = self.view    
  pc?.delegate = self <-- !!! Type AnyObject does not conform to protocol UIPopoverPresentationControllerDelegate !!!

  return aircraftModal
}

我怎样才能使这个函数与任何类一起工作并传递该类的协议(protocol)一致性？

Answer 1

您可以尝试像这样为 UIViewController 创建和扩展:

extension UIViewController {

    func showAircraftPicker(delegate: UIPopoverPresentationControllerDelegate) {

        let storyboard = UIStoryboard(name: "Popovers", bundle: nil)
        var aircraftModal = storyboard.instantiateViewControllerWithIdentifier("AircraftModal") as! AircraftPickerVC
        let pc = aircraftModal.popoverPresentationController
        pc?.sourceView = self.view
        pc?.delegate = delegate

        return aircraftModal
    }
}