问题描述
我正在使用 UIPageViewController 制作书籍页面,页面是将从 Firebase 获取的图像。问题是我遇到了这个错误
(无法将“books”类型的值转换为预期的元素类型“Array.ArrayLiteralElement”(又名“UIViewController”)
'books' 是我为 firebase 制作的结构
import Foundation
import Firebase
struct books {
let bookId: String
let imageURL: String
}
extension booksC {
init(_ dictionary: [String: Any]) {
self.bookId = dictionary["bookId"] as? String ?? "no book id"
self.imageURL = dictionary["imageURL"] as? String ?? "no image url"
}
}
我正在使用这段代码,我的理解是我不能使用图像数组,而我应该使用的是控制器数组,在这种情况下我不知道该怎么做。感谢帮助
import UIKit
import FirebaseFirestore
class PageViewController: UIPageViewController,UIPageViewControllerDataSource,UIPageViewControllerDelegate {
let pageViewController = UIPageViewController(transitionStyle: .pageCurl,navigationorientation: .horizontal,options: nil)
private var pages = [books]()
private var listener: ListenerRegistration?
override func viewDidLoad() {
super.viewDidLoad()
dataSource = self
delegate = self
// index
guard let pagesFirst = pages.last else { return }
setViewControllers([pagesFirst],direction: .reverse,animated: true)
//Todo: add listener
}
func pageViewController(_ pageViewController: UIPageViewController,spineLocationFor orientation: UIInterfaceOrientation) -> UIPageViewController.SpineLocation {
var location = SpineLocation.max
if orientation == .landscapeLeft || orientation == .landscapeRight {
self.pageViewController.isDoubleSided = true
location = .mid
}
return location
}
func pageViewController(_ pageViewController: UIPageViewController,viewControllerBefore viewController: UIViewController) -> UIViewController? {
let index = self.pages.firstIndex(where: {$0 == viewController}) ?? 0
if index == 0 { return nil }
return pages[index - 1]
}
func pageViewController(_ pageViewController: UIPageViewController,viewControllerAfter viewController: UIViewController) -> UIViewController? {
let index = self.pages.firstIndex(where: {$0 == viewController}) ?? 0
if index == pages.count - 1 { return nil }
return pages[index + 1]
}
}
class ImageViewController: UIViewController {
let imageView = UIImageView()
init(image: UIImage) {
imageView.image = image
super.init(nibName: nil,bundle: nil)
}
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(imageView)
imageView.fillSuperview()
imageView.contentMode = .scaleAspectFit
imageView.clipsToBounds = true
imageView.backgroundColor = .white
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
public func setupImage(for book: books){
imageView.kf.setimage(with: URL(string: book.imageURL))
}
}
解决方法
enter code here
您在 private var pages = [books]()
中使用您的数组 setViewControllers
,它期望 UIViewController
setViewControllers
是这样声明的:
func setViewControllers(_ viewControllers: [UIViewController]?,direction: UIPageViewController.NavigationDirection,animated: Bool,completion: ((Bool) -> Void)? = nil)
参数
视图控制器
要显示的一个或多个视图控制器。
方向
导航方向。
动画
一个布尔值,指示是否要对过渡进行动画处理。
我认为您应该创建一个 ImageViewController
实例,然后使用 setupImage(for book: books)
设置图像(您可以访问它,因为它是一个公共方法,最后将该视图控制器分配给您的页面控制器:
guard let pagesFirst = pages.last else { return }
let imageViewController = ImageViewController()
imageViewController.setupImage(for book: pagesFirst)
setViewControllers([imageViewController],direction: .reverse,animated: true)
编辑:
抱歉,就你得到的第二个错误而言,应该是
imageViewController.setupImage(for:pagesFirst)
至于是课外的名字。
对于第一个错误,它为您提供了哪些 init 选项。应该是对的。
还尝试更改以这种方式声明 imageView 的代码:
var imageView : UIImageView = {
let imageView = UIImageView()
imageView.translatesAutoresizingMaskIntoConstraints = false // required if you need to work with autolayout
return imageView
}()
删除:
required init?(coder aDecoder: NSCoder) { fatalError("init(coder:) has not been implemented") }
最后,你应该用大写 B 来命名你的结构体 book
。