我遇到了 iOS/Swift 中 childViewControllers 的多级层次结构的问题。当前设置从最低到最高分为三层：
InfoViewControllerSelectionViewControllerMainViewController
InfoViewController有一个从 XIB 加载的视图。
SelectionViewController包含 aUIStackView和InfoViewControllera UIButton。
MainViewController是顶级 VC，通常嵌入在UINavigationController.
问题
当我添加它时InfoViewController，它的视图直接对MainViewController一切都很好。
func setupInfoViewControllerDirectlyOnMainVC () {
addChildViewController(infoViewController)
infoViewController.view.embedInside(otherView: infoContainerView)
infoViewController.didMove(toParentViewController: self)
}
但是，如果我使用相同的方法添加SelectionViewController到MainViewController，嵌入式InfoViewController不会更新它的 UI - 它总是看起来像它正在控制的未触及的 XIB 文件。当它没有嵌入时，它SelectionViewController的行为符合预期。
如下所示，UI 是可见的，但是通过询问它的 ViewController 对其所做的任何更改都不会显示 - 它看起来与创建它的 XIB 文件完全一样。
下面是从 BasicInfoView 开始的类设置，然后是上面列出的三个 viewController。
基本信息视图
class PLBasicInfoView: PLDesignableViewFromXib {
//
// MARK: Outlets
//
//
@IBOutlet weak var photoView: PFRoundImageView!
@IBOutlet weak var titleLabel: UILabel!
@IBOutlet weak var subtitleLabel: UILabel!
var imageFile:PFFile? {
didSet {
photoView.file = imageFile
photoView.loadInBackground()
}
}
//
// MARK: Initialization
//
//
override var nameOfXib: String {
return "PLBasicInfoView"
}
override var intrinsicContentSize: CGSize {
return CGSize(width: super.intrinsicContentSize.width, height: 56)
}
}
基本信息视图控制器
class PLBasicInfoViewController: UIViewController {
/**
The BasicInfoView which will be managed by this controller.
*/
var basicInfoView = PLBasicInfoView()
/**
This is the master stack view which contains all subviews.
*/
var stackView = UIStackView()
/**
PFFile representing the image to be displayed in the imageView. Setting a valid imageFile object automatically laods the image from the server. If set to nil, the defaultImage is displayed instead.
*/
var imageFile: PFFile? {
didSet {
if imageFile != nil {
basicInfoView.imageFile = imageFile
} else {
basicInfoView.photoView.image = defaultImage
}
}
}
/**
Default UIImage to be displayed in the imageView if there is no imageFile assigned.
*/
var defaultImage: UIImage! {
return #imageLiteral(resourceName: "ios7-camera-outline")
}
/**
Main text of the infoView
*/
var titleText:String? {
didSet {
basicInfoView.titleLabel.isHidden = (titleText == nil)
basicInfoView.titleLabel.text = titleText
}
}
/**
Secondary text of the infoView. Displays under titleText.
*/
var subtitleText:String? {
didSet {
basicInfoView.subtitleLabel.isHidden = (subtitleText == nil)
basicInfoView.subtitleLabel.text = subtitleText
}
}
/**
Embed our stackView into main view. The custom embedInsider(otherView:UIView) method (UIView extension) will take care of the subview additional as well as all layout constraints.
*/
func setupStackView () {
stackView.embedInside(otherView: view)
stackView.axis = .vertical
stackView.addArrangedSubview(basicInfoView)
}
override
func viewDidLoad() {
super.viewDidLoad()
setupStackView()
}
}
选择视图控制器
class PLSelectableInfoViewController: UIViewController {
/**
If true, the info view will be shown and the selection button will be hidden.
*/
var isAssigned = false {
didSet {
selectionButton.isHidden = isAssigned
infoView.isHidden = !isAssigned
}
}
/**
The View controller dispaying the object in question.
*/
var infoViewController: PLBasicInfoViewController! {
return PLBasicInfoViewController()
}
private
var infoView: UIView!
/**
Button on bottom of stack. Intended to allow user to assign a new value to the contact property.
*/
var selectionButton = PLButton()
/**
Stack view containing all subviews.
*/
var stackView = UIStackView()
//
// MARK: UIViewController Overrides
//
//
override
func viewDidLoad() {
super.viewDidLoad()
setupStackView()
addInfoView()
}
private
func setupStackView () {
stackView.embedInside(otherView: view)
stackView.axis = .vertical
}
private
func addInfoView () {
addChildViewController(infoViewController)
infoView = infoViewController.view
stackView.addArrangedSubview(infoView)
infoViewController.didMove(toParentViewController: self)
}
}
一些不相关的代码已被删除
笔记
请注意，在实践中，BasicInfoViewController 和 SelectionViewController 都是子类。例如，我有一个 ContactInfoViewController，它可以传递一个 Contact 对象并显示全名、公司名称和照片（如上所述，这很好用）。还有一个 SelectionViewController 的子类来补充这一点：ContactSelectionViewController。ContactSelectionViewController 也有一个 Contact 对象属性，该属性可以被分配，然后传递给嵌入式 ContactInfoViewController - 这是不显示数据的点。我在下面包含了这些子类以供参考。
ContactInfoViewController
同样，当直接放置在 MainViewController 中时，它可以完美地工作。
class PLContactInfoViewController: PLBasicInfoViewController {
/**
Contact object managed by this controller.
*/
var contact: PLContact? {
didSet {
if contact == nil {
titleText = "Not Set"
subtitleText = nil
return
}
contact?.fetchIfNeededInBackground(block: { (object, error) in
if let _ = object as? PLContact {
self.updateWithContact()
}
})
}
}
override
var defaultImage: UIImage! {
return #imageLiteral(resourceName: "ios7-contact-outline")
}
private
func updateWithContact () {
if let c = contact {
titleText = c.fullName
imageFile = c.photo
c.company?.fetchIfNeededInBackground(block: { (object, error) in
if let comp = object as? PLCompany {
self.subtitleText = comp.name
} else {
self.subtitleText = nil
}
})
}
}
}
联系人选择视图控制器
此 VC 功能正常，但嵌入的 ContactInfoViewController 不显示数据。出于某种原因，ContactInfoViewController 中的视图在嵌入到此控制器中时并未使用数据进行更新。
class PLContactAssignmentViewController: PLSelectableInfoViewController {
/**
The contact currently selected by this contorller
*/
var selectedContact: PLContact? {
didSet {
isAssigned = !(selectedContact == nil)
contactInfoViewController.contact = selectedContact
}
}
override
var infoViewController: PLBasicInfoViewController! {
return PLContactInfoViewController()
}
private
var contactInfoViewController: PLContactInfoViewController {
return infoViewController as! PLContactInfoViewController
}
}