swift - 在 SwiftUI 中使用图像和 PageView 内存不足

Question

我正在编写一个应用程序，该应用程序向用户显示可以浏览和放大的大图片，类似于照片应用程序或书籍。我正在尝试用 SwiftUI 编写这个。我一直在关注苹果网站上的 SwiftUI 教程， 并且我已经修改了代码以读取 json 文件以创建“Imageslides”数组 - 一种保存图像和有关它们的信息的方法。然后，我使用 PageView 和 PageViewController 来显示 ContentView> ContentView 显示图像和一些按钮，这些按钮显示关于我正在显示的图像的文本。我的问题是当我浏览页面时，内存会不断增加，直到应用程序崩溃。现在，如果我使用 UIKit，我可以使用

if let imgPath = Bundle.main.path(forResource: name, ofType: nil)
    {
        return UIImage(contentsOfFile: imgPath)
    }

但是我看不到如何在swiftUI中使用图像来使用contentsOfFile，或者在不需要时让图像超出内存的另一种方式。我将图像放在资源文件夹中，而不是在资产库中。谢谢你的帮助。

//data.swift - reading from json, mainly from apple's tutorials
import Foundation
import UIKit
import SwiftUI

let imageData: [Imageslide] = load("imageData.json")

func load<T: Decodable>(_ filename: String) -> T {
    let data: Data

    guard let file = Bundle.main.url(forResource: filename, withExtension: nil)
        else {
            fatalError("Couldn't find \(filename) in main bundle.")
    }

    do {
        data = try Data(contentsOf: file)
    } catch {
        fatalError("Couldn't load \(filename) from main bundle:\n\(error)")
    }

    do {
        let decoder = JSONDecoder()
        return try decoder.decode(T.self, from: data)
    } catch {
        fatalError("Couldn't parse \(filename) as \(T.self):\n\(error)")
    }
}

final class ImageStore {
    typealias _ImageDictionary = [String: CGImage]
    fileprivate var images: _ImageDictionary = [:]

    fileprivate static var scale = 2

    static var shared = ImageStore()

    func image(name: String) -> Image {
        let index = _guaranteeImage(name: name)

        return Image(images.values[index], scale: CGFloat(ImageStore.scale), label: Text(name))
    }

    static func loadImage(name: String) -> CGImage {
        guard
            let url = Bundle.main.url(forResource: name, withExtension: "png"),
            let imageSource = CGImageSourceCreateWithURL(url as NSURL, nil),
            let image = CGImageSourceCreateImageAtIndex(imageSource, 0, nil)
        else {
            fatalError("Couldn't load image \(name).jpg from main bundle.")
        }
        return image
    }

    fileprivate func _guaranteeImage(name: String) -> _ImageDictionary.Index {
        if let index = images.index(forKey: name) { return index }

        images[name] = ImageStore.loadImage(name: name)
        return images.index(forKey: name)!
    }
}

//imageslide.swift - abstract for holding my image slide and button info 

import SwiftUI

struct buttonInfo: Hashable, Codable{
    var text: String? = nil
    var coords: [Int]? = nil
    public enum CodingKeys : String, CodingKey {
        case text, coords
    }
    init(from decoder: Decoder) throws {
      let container = try decoder.container(keyedBy: CodingKeys.self)
      self.text = try container.decodeIfPresent(String.self, forKey: .text)
      self.coords = try container.decodeIfPresent([Int].self, forKey: .coords)
    }
      func encode(to encoder: Encoder) throws {
      var container = encoder.container(keyedBy: CodingKeys.self)
      try container.encode(self.text, forKey: .text)
      try container.encode(self.coords, forKey: .coords)
    }
}

struct Imageslide: Hashable, Codable, Identifiable {

    public var imagename: String
   public var id: Int
    public var noButtons: Int

    public var buttoninfo: [buttonInfo]? = nil

    public enum CodingKeys : String, CodingKey {
        case imagename, id, noButtons, buttoninfo
        case imageslide = "Imageslide"
    }
    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        let imageslide = try container.nestedContainer(keyedBy:
        CodingKeys.self, forKey: .imageslide)
        self.imagename = try imageslide.decode(String.self, forKey: .imagename)
        self.id = try imageslide.decode(Int.self, forKey: .id)
        self.noButtons = try imageslide.decode(Int.self, forKey: .id)
        self.buttoninfo = try imageslide.decodeIfPresent([buttonInfo].self, forKey: .buttoninfo)
    }

   func encode(to encoder: Encoder) throws {
     var container = encoder.container(keyedBy: CodingKeys.self)
     var imageslide = container.nestedContainer(keyedBy: CodingKeys.self, forKey: .imageslide)
     try imageslide.encode(self.imagename, forKey: .imagename)
     try imageslide.encode(self.id, forKey: .id)
     try imageslide.encode(self.noButtons, forKey: .noButtons)
    try imageslide.encode(self.buttoninfo, forKey: .buttoninfo)
    }
}

extension Imageslide {
    var image: Image {
        ImageStore.shared.image(name: imagename)
    }
}



struct ButtonDataStore: Codable{
    var buttonData: [buttonInfo]
}

//contentview.swift - used to show the images and buttons
import SwiftUI

struct ContentView: View {
    var imageslide: Imageslide
    @State private var button1Visible = true
    @State var scale: CGFloat = 1.0

    var body: some View {

        ZStack {


            Image(uiImage: (UIImage(named: imageslide.imagename)!))
           //   imageslide.image
                //   Image(imageslide.imagename)
                .resizable()
           .frame(width: 2732/2, height: 2048/2)
      //Pinch to zoom code goes here

                .background(/*@START_MENU_TOKEN@*/Color.black/*@END_MENU_TOKEN@*/)

                    .edgesIgnoringSafeArea(.all)
                .statusBar(hidden: true)

            if (imageslide.noButtons != 0)
            {
                if imageslide.buttoninfo != nil
                {
                    ForEach(imageslide.buttoninfo!, id: \.self) {count in

                        ButtonView(text: count.text!, xcoord: count.coords![0], ycoord: count.coords![1], xcoordo: count.coords![2], ycoordo: count.coords![3])
                    }
                }
        }
        }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {

        //ContentView(imageslide: imageData[0])
        ContentView(imageslide: imageData[1]).previewLayout(
            .fixed(width: 2732/2, height: 2048/2)     
        )
    }
}
}

//PageViewController.swift

import SwiftUI
import UIKit

struct PageViewController: UIViewControllerRepresentable {
    var controllers: [UIViewController]
    @Binding var currentPage: Int

    func makeCoordinator() -> Coordinator {
        Coordinator(self)
    }

    func makeUIViewController(context: Context) -> UIPageViewController {
         let pageViewController = UIPageViewController(
             transitionStyle: .scroll,
             navigationOrientation: .horizontal)
        pageViewController.dataSource = context.coordinator
        pageViewController.delegate = context.coordinator

         return pageViewController
     }


    func updateUIViewController(_ pageViewController: UIPageViewController, context: Context) {
        pageViewController.setViewControllers(
             [controllers[currentPage]], direction: .forward, animated: true)
    }


    class Coordinator: NSObject, UIPageViewControllerDataSource, UIPageViewControllerDelegate {
        var parent: PageViewController

        init(_ pageViewController: PageViewController) {
            self.parent = pageViewController
        }


    func pageViewController(
        _ pageViewController: UIPageViewController,
        viewControllerBefore viewController: UIViewController) -> UIViewController?
    {
        guard let index = parent.controllers.firstIndex(of: viewController) else {
            return nil
        }
        if index == 0 {
            return parent.controllers.last
        }
        return parent.controllers[index - 1]
    }

    func pageViewController(
        _ pageViewController: UIPageViewController,
        viewControllerAfter viewController: UIViewController) -> UIViewController?
    {
        guard let index = parent.controllers.firstIndex(of: viewController) else {
            return nil
        }
        if index + 1 == parent.controllers.count {
            return parent.controllers.first
        }
        return parent.controllers[index + 1]

    }

    func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {
        if completed,
            let visibleViewController = pageViewController.viewControllers?.first,
            let index = parent.controllers.firstIndex(of: visibleViewController)
        {
            parent.currentPage = index
        }
    }
}

}

//pageview.swift 
import SwiftUI

struct PageView<Page: View>: View {
    var viewControllers: [UIHostingController<Page>]

    @State var currentPage = 0

    init(_ views: [Page]) {
        self.viewControllers = views.map { UIHostingController(rootView: $0) }
    }

    var body: some View {
         PageViewController(controllers: viewControllers, currentPage: $currentPage)
    }
}

struct PageView_Previews: PreviewProvider {
    static var previews: some View {

        PageView(imageData.map {ContentView(imageslide: $0)})
    }
}

我正在使用的 JSON 示例。

   {
      "Imageslide":{
         "imagename":"MOS_SHB_1",
         "id":1001,
         "noButtons":0
      }
   },
   {
      "Imageslide":{
         "imagename":"MOS_SHB_2",
         "id":1002,
         "noButtons":0
      }
   },
   {
      "Imageslide":{
         "imagename":"MOS_SHB_3",
         "id":1003,
         "noButtons":1,
         "buttoninfo":[
            {
               "text":"The two halves of the arch touched for the first time. Workers riveted both top and bottom sections of the arch together, and the arch became self-supporting, allowing the support cables to be removed. On 20 August 1930 the joining of the arches was celebrated by flying the flags of Australia and the United Kingdom from the jibs of the creeper cranes.",
               "coords":[
                  -150,
                  220,
                  200,
                  200
               ]
            }
         ]
      }
   },

标签： swiftmemoryuikitswiftuiuipageviewcontroller

Answer 1

UIImage像以前一样创建

let imageModel = UIImage(contentsOfFile: imgPath)

并将其body用作Image视图模型

Image(uiImage: imageModel ?? UIImage())