Swift 显示为popover的UIViewController是否可以是其自己的PopoOverPresentationController委托？
在下面显示的项目中，有一个Swift 显示为popover的UIViewController是否可以是其自己的PopoOverPresentationController委托？,swift,uiviewcontroller,popover,uipresentationcontroller,Swift,Uiviewcontroller,Popover,Uipresentationcontroller,在下面显示的项目中，有一个InitialViewController，它有一个标记为“ShowPopover”的按钮。当点击该按钮时，应用程序应将第二个视图控制器（PopoverViewController）显示为popover。第二个视图控制器只有一个标签，上面写着“Popover！” 如果InitialViewController负责实例化PopoverViewController，检索popoverPresentationController，然后将popoverPresentation
InitialViewControllerPopoverViewControllerInitialViewControllerPopoverViewControllerpopoverPresentationController委托设置为自身（设置为InitialViewController
），则此操作正常。您可以在下面看到结果：
但是，为了实现最大的可重用性，如果InitialViewController
不需要知道演示控制器是如何委派的，那就太好了。我认为PopoverViewController
应该可以将自己设置为popoverPresentationController的委托。我已经在viewDidLoad
或pooverviewcontroller
的viewwillbeen
功能中尝试过这一点。但是，在这两种情况下，PopoverViewController
都以模式显示，如下所示：
import UIKit
// MARK: - UIViewController subclass
class InitialViewController: UIViewController {
struct Lets {
static let storyboardName = "Main"
static let popoverStoryboardID = "Popover View Controller"
}
@IBAction func showPopoverButton(_ sender: UIButton) {
// instantiate & present the popover view controller
let storyboard = UIStoryboard(name: Lets.storyboardName,
bundle: nil )
let popoverViewController =
storyboard.instantiateViewController(withIdentifier: Lets.popoverStoryboardID )
popoverViewController.modalPresentationStyle = .popover
guard let popoverPresenter = popoverViewController.popoverPresentationController
else {
fatalError( "could not retrieve a pointer to the 'popoverPresentationController' property of popoverViewController")
}
present(popoverViewController,
animated: true,
completion: nil )
// Retrieve and configure UIPopoverPresentationController
// after presentation (per
// https://developer.apple.com/documentation/uikit/uipopoverpresentationcontroller)
popoverPresenter.permittedArrowDirections = .any
let button = sender
popoverPresenter.sourceView = button
popoverPresenter.sourceRect = button.bounds
}
}
import UIKit
// MARK: - main UIViewController subclass
class PopoverViewController: UIViewController {
// MARK: API
var factorForMarginsAroundButton: CGFloat = 1.2
// MARK: outlets and actions
@IBOutlet weak var popoverLabel: UILabel!
// MARK: lifecycle
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear( animated )
// set the preferred size for popover presentations
let labelSize =
popoverLabel.systemLayoutSizeFitting( UILayoutFittingCompressedSize )
let labelWithMargins =
CGSize(width: labelSize.width * factorForMarginsAroundButton,
height: labelSize.height * factorForMarginsAroundButton )
preferredContentSize = labelWithMargins
// set the delegate for the popoverPresentationController to self
popoverPresentationController?.delegate = self
}
}
// MARK: - UIPopoverPresentationControllerDelegate
// (inherits from protocol UIAdaptivePresentationControllerDelegate)
extension PopoverViewController: UIPopoverPresentationControllerDelegate
{
func adaptivePresentationStyle(for controller: UIPresentationController,
traitCollection: UITraitCollection)
-> UIModalPresentationStyle{
return .none
}
}
所有代码仅包含在InitialViewController
和PopoverViewController
中。InitialViewController
故障版本中使用的代码如下所示：
import UIKit
// MARK: - UIViewController subclass
class InitialViewController: UIViewController {
struct Lets {
static let storyboardName = "Main"
static let popoverStoryboardID = "Popover View Controller"
}
@IBAction func showPopoverButton(_ sender: UIButton) {
// instantiate & present the popover view controller
let storyboard = UIStoryboard(name: Lets.storyboardName,
bundle: nil )
let popoverViewController =
storyboard.instantiateViewController(withIdentifier: Lets.popoverStoryboardID )
popoverViewController.modalPresentationStyle = .popover
guard let popoverPresenter = popoverViewController.popoverPresentationController
else {
fatalError( "could not retrieve a pointer to the 'popoverPresentationController' property of popoverViewController")
}
present(popoverViewController,
animated: true,
completion: nil )
// Retrieve and configure UIPopoverPresentationController
// after presentation (per
// https://developer.apple.com/documentation/uikit/uipopoverpresentationcontroller)
popoverPresenter.permittedArrowDirections = .any
let button = sender
popoverPresenter.sourceView = button
popoverPresenter.sourceRect = button.bounds
}
}
import UIKit
// MARK: - main UIViewController subclass
class PopoverViewController: UIViewController {
// MARK: API
var factorForMarginsAroundButton: CGFloat = 1.2
// MARK: outlets and actions
@IBOutlet weak var popoverLabel: UILabel!
// MARK: lifecycle
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear( animated )
// set the preferred size for popover presentations
let labelSize =
popoverLabel.systemLayoutSizeFitting( UILayoutFittingCompressedSize )
let labelWithMargins =
CGSize(width: labelSize.width * factorForMarginsAroundButton,
height: labelSize.height * factorForMarginsAroundButton )
preferredContentSize = labelWithMargins
// set the delegate for the popoverPresentationController to self
popoverPresentationController?.delegate = self
}
}
// MARK: - UIPopoverPresentationControllerDelegate
// (inherits from protocol UIAdaptivePresentationControllerDelegate)
extension PopoverViewController: UIPopoverPresentationControllerDelegate
{
func adaptivePresentationStyle(for controller: UIPresentationController,
traitCollection: UITraitCollection)
-> UIModalPresentationStyle{
return .none
}
}
失败PopOverview控制器
中的代码如下所示：
import UIKit
// MARK: - UIViewController subclass
class InitialViewController: UIViewController {
struct Lets {
static let storyboardName = "Main"
static let popoverStoryboardID = "Popover View Controller"
}
@IBAction func showPopoverButton(_ sender: UIButton) {
// instantiate & present the popover view controller
let storyboard = UIStoryboard(name: Lets.storyboardName,
bundle: nil )
let popoverViewController =
storyboard.instantiateViewController(withIdentifier: Lets.popoverStoryboardID )
popoverViewController.modalPresentationStyle = .popover
guard let popoverPresenter = popoverViewController.popoverPresentationController
else {
fatalError( "could not retrieve a pointer to the 'popoverPresentationController' property of popoverViewController")
}
present(popoverViewController,
animated: true,
completion: nil )
// Retrieve and configure UIPopoverPresentationController
// after presentation (per
// https://developer.apple.com/documentation/uikit/uipopoverpresentationcontroller)
popoverPresenter.permittedArrowDirections = .any
let button = sender
popoverPresenter.sourceView = button
popoverPresenter.sourceRect = button.bounds
}
}
import UIKit
// MARK: - main UIViewController subclass
class PopoverViewController: UIViewController {
// MARK: API
var factorForMarginsAroundButton: CGFloat = 1.2
// MARK: outlets and actions
@IBOutlet weak var popoverLabel: UILabel!
// MARK: lifecycle
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear( animated )
// set the preferred size for popover presentations
let labelSize =
popoverLabel.systemLayoutSizeFitting( UILayoutFittingCompressedSize )
let labelWithMargins =
CGSize(width: labelSize.width * factorForMarginsAroundButton,
height: labelSize.height * factorForMarginsAroundButton )
preferredContentSize = labelWithMargins
// set the delegate for the popoverPresentationController to self
popoverPresentationController?.delegate = self
}
}
// MARK: - UIPopoverPresentationControllerDelegate
// (inherits from protocol UIAdaptivePresentationControllerDelegate)
extension PopoverViewController: UIPopoverPresentationControllerDelegate
{
func adaptivePresentationStyle(for controller: UIPresentationController,
traitCollection: UITraitCollection)
-> UIModalPresentationStyle{
return .none
}
}
显示为popover的视图控制器是否可以作为其自己的PopoOverPresentationController
的代理
我使用的是Xcode 8.0、Swift 3.1，目标是iOS 10.0，这当然是可能的。你在处理一个时间问题。您需要在出现视图之前设置代理。不幸的是，没有方便的视图生命周期函数来插入分配，所以我改为这样做
在PopoverViewController
类中，在重写的getter中分配代理。如果你愿意，你可以把作业设为有条件的。这将创建一个永久关系，因此其他代码不会通过分配它来“覆盖”委托
override var popoverPresentationController: UIPopoverPresentationController? {
get {
let ppc = super.popoverPresentationController
ppc?.delegate = self
return ppc
}
}
谢谢你，艾伦！我刚试过，效果很好。我同意这是一个时间问题，但我不知道覆盖属性会提供正确的时间。你能告诉我们你是怎么想出来的吗？老实说，一点尝试和错误。我发现初始化后popoverPresentationController还不存在，viewDidLoad已经很晚了。所以我在系统的任何部分中插入了我自己，使用popoverPresentationControllerHmm，我想我明白了。除非popoverPresentationController已经初始化并使用，否则ViewDidLoad不会发生，因此popoverPresentationController的获取必须在初始化之后、ViewDidLoad之前。再次感谢您的友好（非常迅速）回复。