PDF未从App重新启动iOS上的文档文件夹加载

Question

我有一个从服务器下载并保存的 pdf。接下来我从UIWebView 中的文件路径打开文件。这在我第一次启动应用程序时有效。当我再次重新启动应用程序时，即使文件路径相同，文档也无法打开。此外，该文档确实存在于应用程序的文档文件夹中。

我正在做类似的事情：-

SaveToFolder.cs

var filePath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Personal), fileName);

using (FileStream destinationStream = File.Create(filePath))
{
     await documentStream.CopyToAsync(destinationStream);
}

第一次保存文件后的文件路径：-

 /var/mobile/Containers/Data/Application/C3EA2325-81CA-4EC9-8C03-479ACF7EE330/Documents/Insufficiency.pdf

应用重新启动时的文件路径

/var/mobile/Containers/Data/Application/C3EA2325-81CA-4EC9-8C03-479ACF7EE330/Documents/Insufficiency.pdf  

是不是我做错了什么？

Answer 1

不久前我遇到了同样的问题。可以参考Can't find saved file (in device) after restarting the app

根据答案

You shouldn't store raw file paths for persistence (or if you do, know that the root can move on you). A better practice would be to only store the relative part of the path and always attach it to the current "root" path in question (particularly if you might be sharing data across devices as with iCloud).

也许你的根也在改变。您可以更改方法并将带有默认路径的文件名附加到您的文档文件夹中，就像在 Xamarin 中一样：-

var docsPath = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments); filePath = docsPath +"/" + "Insuffeciency.pdf";

另外，请考虑在保存文件时将您的 Personal 文件夹更改为 MyDocuments 文件夹。

Answer 2

我在 iOS 中创建了一个用于读写文件的文件。请在 iOS 中查看

using System;
using Xamarin.Forms;
using FileReader.iOS;
using System.IO;
using FileReader;
using Foundation;
using System.Linq;
using System.Threading.Tasks;

[assembly: Dependency(typeof(SaveAndLoadiOS))]

namespace FileReader.iOS
{
    public class SaveAndLoadiOS : LoadAndSave
    {
        public static string DocumentPath
        {
            get
            {
                var documentURL = NSFileManager.DefaultManager.GetUrls(NSSearchPathDirectory.DocumentDirectory, NSSearchPathDomain.User).Last();
                return documentURL.Path;
            }
        }

        public string CreatePath(string fileName)
        {
            return Path.Combine(DocumentPath, fileName);
        }

        public async Task SaveTextAsync(string fileName, string text)
        {
            string path = CreatePath(fileName);
            if (IsFileExits(fileName))
            {
                File.Delete(path);
            }
            using (StreamWriter sw = File.CreateText(path))
                await sw.WriteAsync(text);  
        }

        public async Task<string>  LaodTextAsync(string fileName)
        {
            string path = CreatePath(fileName);
            using (StreamReader sr = File.OpenText(path))
                return await sr.ReadToEndAsync();
        }

        public bool IsFileExits(string fileName)
        {
            return File.Exists (CreatePath(fileName));
        }
    }
}

为了从我的 .CS 类（ContentPage 的子类）中读取，下面是代码

var tempFileService =  DependencyService.Get<LoadAndSave>();
var itemFile = await tempFileService.LaodTextAsync(tempFile.StoredFileName);
var rootobject = JsonConvert.DeserializeObject<Rootobject>(itemFile);

其中LoadAndSave是如下接口

using System;
using System.Threading.Tasks;

namespace FileReader
{
    public interface LoadAndSave
    {
        Task SaveTextAsync(string fileName, string text);
        Task<string> LaodTextAsync(string fileName);
        bool IsFileExits(string fileName);
    }
}

希望对你有帮助。