带有点图像的自定义 UIPageControl

Question

当我需要自定义 UIPageControl 时，我使用了 this 和 this 解决方案。

为我们拥有的新版本的 swift 稍微修改一下：

class myPageControl: UIPageControl {
    var activeImage: UIImage!
    var inactiveImage: UIImage!

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        activeImage = UIImage(named: "active.png")!
        inactiveImage = UIImage(named: "inactive.png")!
    }

    func updateDots()
    {
        for i in 0 ..< self.subviews.count
        {
            let dot : UIImageView = imageViewForSubview(self.subviews[i])
            if (i == self.currentPage) {
                dot.image = activeImage
            }
            else {
                dot.image = inactiveImage
            }
        }
    }

    func imageViewForSubview(view: UIView) -> UIImageView {
        var dot: UIImageView? = nil
        if (view.isKindOfClass(UIView)) {
            for subview: UIView in view.subviews {
                if (subview is UIImageView) {
                    dot = (subview as! UIImageView)
                }
            }
            if dot == nil {
                dot = UIImageView(frame: CGRectMake(0.0, 0.0, view.frame.size.width, view.frame.size.height))
                view.addSubview(dot!)
            }
        }
        else {
            dot = (view as! UIImageView)
        }
        return dot!
    }

    func setPage(page: Int) {
        super.currentPage = page
        self.updateDots()
    }
}

我的问题是当你第一次启动应用程序时我无法更改图片。 只有当页面改变时才会改变。

在viewDidLoad()中，我添加了setPage(0)和updateDots()，但是没有结果。我可能做错了什么？

Answer 1

Swift 3.0 ...您知道您是否可以接受声明的风险：“修改现有控件的子视图很脆弱”。

您必须在 viewDidAppear() 和页面控件的 valueChanged 处理程序中调用“updateDots()”。

 import UIKit

 class CustomImagePageControl: UIPageControl {

   let activeImage:UIImage = UIImage(named: "SelectedPage")!
   let inactiveImage:UIImage = UIImage(named: "UnselectedPage")!

   override func awakeFromNib() {
         super.awakeFromNib()

         self.pageIndicatorTintColor = UIColor.clear
         self.currentPageIndicatorTintColor = UIColor.clear
         self.clipsToBounds = false
    }

    func updateDots() {
         var i = 0
         for view in self.subviews {
             if let imageView = self.imageForSubview(view) {
                 if i == self.currentPage {
                     imageView.image = self.activeImage
                 } else {
                     imageView.image = self.inactiveImage
                 }
                 i = i + 1
             } else {
                 var dotImage = self.inactiveImage
                 if i == self.currentPage {
                     dotImage = self.activeImage
                 }
                 view.clipsToBounds = false
                 view.addSubview(UIImageView(image:dotImage))
                 i = i + 1
             }
         }
     }

     fileprivate func imageForSubview(_ view:UIView) -> UIImageView? {
         var dot:UIImageView?

         if let dotImageView = view as? UIImageView {
             dot = dotImageView
         } else {
             for foundView in view.subviews {
                 if let imageView = foundView as? UIImageView {
                     dot = imageView
                     break
                 }
             }
         }

         return dot
     }
 }

Answer 2

我稍微改进了@CodenameDuchess 的回答。您还可以自定义 xibs/storyboards 上的图像。

class CustomPageControl: UIPageControl {

@IBInspectable var currentPageImage: UIImage?

@IBInspectable var otherPagesImage: UIImage?

override var numberOfPages: Int {
    didSet {
        updateDots()
    }
}

override var currentPage: Int {
    didSet {
        updateDots()
    }
}

override func awakeFromNib() {
    super.awakeFromNib()
    pageIndicatorTintColor = .clear
    currentPageIndicatorTintColor = .clear
    clipsToBounds = false
}

private func updateDots() {

    for (index, subview) in subviews.enumerated() {
        let imageView: UIImageView
        if let existingImageview = getImageView(forSubview: subview) {
            imageView = existingImageview
        } else {
            imageView = UIImageView(image: otherPagesImage)

            imageView.center = subview.center
            subview.addSubview(imageView)
            subview.clipsToBounds = false
        }
        imageView.image = currentPage == index ? currentPageImage : otherPagesImage
    }
}

private func getImageView(forSubview view: UIView) -> UIImageView? {
    if let imageView = view as? UIImageView {
        return imageView
    } else {
        let view = view.subviews.first { (view) -> Bool in
            return view is UIImageView
        } as? UIImageView

        return view
    }
}
}

Answer 3

你可以使用UIStackView来达到你想要的效果。

将您的activeImageView 和其他inactiveImageViews 放入aStackView。不仅仅是在scrollViewDidScroll(_:) 中更改activeImageView 的索引。

func scrollViewDidScroll(_ scrollView: UIScrollView) {
  let index = Int(scrollView.contentOffset.x / scrollView.frame.width)
  aStackView.insertArrangedSubview(activeImageView, at: index)
}  

ps。 UIStackView 的insertArrangedSubview(_:at:) 只是更新已排列子视图的堆栈索引，如果它已经在排列子视图列表中。

Answer 4

Apple 为 UIPageControll 引入了一些新的 API。从 iOS 14 开始，可以选择提供自定义图像。

这是支持 iOS 14 的更新代码

class CustomPageControl: UIPageControl {

@IBInspectable var currentPageImage: UIImage?

@IBInspectable var otherPagesImage: UIImage?

override var numberOfPages: Int {
    didSet {
        updateDots()
    }
}

override var currentPage: Int {
    didSet {
        updateDots()
    }
}

override func awakeFromNib() {
    super.awakeFromNib()
    if #available(iOS 14.0, *) {
        defaultConfigurationForiOS14AndAbove()
    } else {
        pageIndicatorTintColor = .clear
        currentPageIndicatorTintColor = .clear
        clipsToBounds = false
    }
}

private func defaultConfigurationForiOS14AndAbove() {
    if #available(iOS 14.0, *) {
        for index in 0..<numberOfPages {
            let image = index == currentPage ? currentPageImage : otherPagesImage
            setIndicatorImage(image, forPage: index)
        }

        // give the same color as "otherPagesImage" color.
        pageIndicatorTintColor = .gray
        
        // give the same color as "currentPageImage" color.
        currentPageIndicatorTintColor = .red 
        /*
         Note: If Tint color set to default, Indicator image is not showing. So, give the same tint color based on your Custome Image.
        */
    }
}

private func updateDots() {
    if #available(iOS 14.0, *) {
        defaultConfigurationForiOS14AndAbove()
    } else {
        for (index, subview) in subviews.enumerated() {
            let imageView: UIImageView
            if let existingImageview = getImageView(forSubview: subview) {
                imageView = existingImageview
            } else {
                imageView = UIImageView(image: otherPagesImage)
                
                imageView.center = subview.center
                subview.addSubview(imageView)
                subview.clipsToBounds = false
            }
            imageView.image = currentPage == index ? currentPageImage : otherPagesImage
        }
    }
}

private func getImageView(forSubview view: UIView) -> UIImageView? {
    if let imageView = view as? UIImageView {
        return imageView
    } else {
        let view = view.subviews.first { (view) -> Bool in
            return view is UIImageView
        } as? UIImageView

        return view
    }
}
}