PageViewController显示其他视图控制器的一部分

Question

我有一个UIPageViewController和2个UIViewControllers，两个都以UIImageView为背景，内容模式设置为scaleAspectFill。出于某种原因，这导致第二个UIViewController在第一个滚动到第二个UIViewController时部分可见，而不是滚动回到第一个UIViewController。

可以在以下位置找到复制项目：https://github.com/Jasperav/PageViewControllerGlitch。代码也在照片下方。

照片（空间是第一UIViewController，绿色部分是第二UIViewController）：

代码（我不使用情节提要，对于具有正确窗口的复制路径，请使用github链接）：

import UIKit

class PageViewController: UIPageViewController, UIPageViewControllerDataSource, UIPageViewControllerDelegate {

    private let pageViewControllers: [UIViewController] = [VC1(), VC2()]

    init() {
        super.init(transitionStyle: .scroll, navigationOrientation: .horizontal, options: nil)

        dataSource = self
        delegate = self

        setViewControllers([pageViewControllers.first!], direction: .forward, animated: false, completion: nil)
    }

    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    func presentationCount(for pageViewController: UIPageViewController) -> Int {
        return pageViewControllers.count
    }

    func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController? {
        guard let index = pageViewControllers.index(of: viewController), index > 0 else { return nil }

        let previousIndex = index - 1

        return pageViewControllers[previousIndex]
    }

    func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController? {
        guard let index = pageViewControllers.index(of: viewController), (index + 1) != pageViewControllers.count else { return nil }

        return pageViewControllers[index + 1]
    }
}

class VC: UIViewController {
    init(background: UIImage) {
        super.init(nibName: nil, bundle: nil)

        let backgroundImageView = UIImageView(image: background)

        backgroundImageView.contentMode = .scaleAspectFill

        view.addSubview(backgroundImageView)

        backgroundImageView.translatesAutoresizingMaskIntoConstraints = false

        backgroundImageView.topAnchor.constraint(equalTo: view.topAnchor).isActive = true
        backgroundImageView.bottomAnchor.constraint(equalTo: view.bottomAnchor).isActive = true
        backgroundImageView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
        backgroundImageView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

class VC1: VC {
    init() {
        super.init(background: #imageLiteral(resourceName: "bg1"))
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

class VC2: VC {
    init() {
        super.init(background: #imageLiteral(resourceName: "bg2"))
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

Answer 1

当使用AspectFill作为内容模式时，如果图像大于UImageView的尺寸，则图像会溢出。要解决此问题，您可以裁剪其子视图：

backgroundImageView.contentMode = .scaleAspectFill
backgroundImageView.clipsToBounds = true

另一种解决方案是尝试使用另一种内容模式，例如.scaleToFill。 希望能对您有所帮助，我只是在您的演示项目中尝试了此解决方案，并且都可以使用。