Develop Reference

Showing local pdf files from documents folder in xamarin ios webview [duplicate]

Im currently having an issue loading a local pdf into a webview. I have the code which works without any errors and when I run it on the iPad simulator, it works absolutely perfect. However, the issue comes when I try to run it on a physical iPad device. When I run it and it gets to the point where it needs to show the PDF, the webview loads but there is no PDF shown in the webview.
The PDF is actually generated by the app and I store it inside a directory inside the library folder.
Code to show the PDF in the WebView:
public void LoadPdfToWebView(string pdfPath)
{
//Console.WriteLine("Load request started");
WebView.LoadRequest(new NSUrlRequest(new NSUrl(pdfPath, false)));
View.AddSubview(WebView);
//Console.WriteLine("Load request Finished");
}
Not really sure why this would be the case and hopefully somebody can help.

I've just had to fix this for an app and thought I'd post the solution
This is for WKWebView which is a requirement from Apple as of Dec 2020 though the deadline has been temporarily extended
Xaml PdfWebView ContentPage
<controls:PdfWebView
Source="{Binding PDFSource}"
HeightRequest="1000"
WidthRequest="1000"/>
control
namespace XForms.Controls
{
public class PdfWebView : WebView { }
}
VM, only the relevant part
private string _pdfSource;
public string PDFSource
{
get => _pdfSource;
set
{
if (Device.RuntimePlatform == Device.Android && value.StartsWith("file:") == false)
{
value = $"file:///android_asset/pdfjs/web/viewer.html?file=file:///{WebUtility.UrlEncode(value)}";
}
SetProperty(ref _pdfSource, value);
}
}
iOS renderer for PdfWebView
using UIKit;
using Xamarin.Forms;
using Xamarin.Forms.Platform.iOS;
using XForms.Controls;
using WebKit;
using Foundation;
[assembly: ExportRenderer(typeof(PdfWebView), typeof(iOSUI.Renderers.PdfWebViewRenderer))]
namespace iOSUI.Renderers
{
public class PdfWebViewRenderer : ViewRenderer<WebView, WKWebView>
{
protected override void OnElementChanged(ElementChangedEventArgs<WebView> e)
{
base.OnElementChanged(e);
if (Control == null)
{
var wkWebViewConfiguration = new WKWebViewConfiguration();
var wkWebView = new WKWebView(Frame, wkWebViewConfiguration)
{
AutoresizingMask = UIViewAutoresizing.FlexibleWidth | UIViewAutoresizing.FlexibleHeight
};
SetNativeControl(wkWebView);
}
if (e.NewElement != null)
{
if (string.IsNullOrEmpty(((UrlWebViewSource)e.NewElement.Source)?.Url) == false)
{
var url = ((UrlWebViewSource)e.NewElement.Source).Url;
if(url.StartsWith("http"))
{
Control.LoadRequest(new NSUrlRequest(new NSUrl(url)));
}
else
{
Control.LoadFileUrl(new NSUrl($"file://{url}"), new NSUrl($"file://{url}"));
}
}
}
}
}
}
Android Renderer
using System.Net;
using Android.Content;
using Android.Views;
using Android.Webkit;
using XForms.Controls;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;
[assembly: ExportRenderer(typeof(PdfWebView), typeof(AndroidUI.Renderers.PDFViewRenderer))]
namespace AndroidUI.Renderers
{
public class PDFViewRenderer : WebViewRenderer
{
public PDFViewRenderer(Context context) : base(context) { }
protected override void OnElementChanged(ElementChangedEventArgs<Xamarin.Forms.WebView> e)
{
base.OnElementChanged(e);
if (e.NewElement != null)
{
Control.Settings.JavaScriptEnabled = true;
Control.Settings.DomStorageEnabled = true;
Control.Settings.AllowFileAccess = true;
Control.Settings.AllowFileAccessFromFileURLs = true;
Control.Settings.AllowUniversalAccessFromFileURLs = true;
Control.SetWebChromeClient(new WebChromeClient());
}
}
// If you want to enable scrolling in WebView uncomment the following lines.
public override bool DispatchTouchEvent(MotionEvent e)
{
Parent.RequestDisallowInterceptTouchEvent(true);
return base.DispatchTouchEvent(e);
}
}
}
This solution uses pdfjs in Android and WKWebview in iOS to render the PDF
The PDFSource is the full path to the file, I use System.IO .net standard calls to handle this in a cross platform way
All the files are stored in (I have a method called GetFullPath to return the cross platform common path)
Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments)
Combined with a filename with Path.Combine
Path.Combine(GetFullPath(), fileName);
That is the PDFSource that gets set in the VM
The Pdfjs library files are just copied into Assets/pdfjs for Android
The magic for iOS is just calling LoadFileUrl instead of LoadRequest and prepending "file://"
I've slightly sanitised our namespaces so some of them wont resolve like XForms.Controls and so on that refer to our internal code

In Xamarin.IOS to show a document type other than HTML in a UIWebView:
Add the document (for example, a PDF) to your Xamarin.iOS project. Set the Build Action to BundleResource. You can set the build action for a file by right-clicking on that file and and choosing Build Action in the menu that opens.
Create a UIWebView and add it to a view:
webView = new UIWebView (View.Bounds);
View.AddSubview(webView);
Load the file using NSUrl and NSUrlRequest classes:
string fileName = "Loading a Web Page.pdf"; // remember case-sensitive
string localDocUrl = Path.Combine (NSBundle.MainBundle.BundlePath, fileName);
webView.LoadRequest(new NSUrlRequest(new NSUrl(localDocUrl, false)));
webView.ScalesPageToFit = true;
You can refer to this officical steps.If have problems or other needs, you can refer to this link
If you can't read the resources in the bundle, you can put the resource cache in the temp directory of the sandbox and try to read it using LoadRequest.

File.Exists and SpreadsheetDocument.Open returning File Not Found Exception in UWP Application

Im having an issue with using DocumentFormat.OpenXml.Packaging.SpreadsheetDocument.Open is not opening a spreadsheet, it returns a file not found exception. The class i'm using has worked many times before, but i've never used it in a UWP project.
I've created a simple example and found that I get the same issue when using File.Exists i've include all the using statements i use if that helps.
Does anyone know why the File.Exists cannot detect the file?
and yes i've triple checked the file does exist on D:!
C# UWP Project created using UWP Template Studio [MainPage.xaml.cs]
using System;
using System.IO;
using System.Data;
using System.Linq;
using System.Diagnostics;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using Windows.UI.Xaml;
using UWP_APP.ViewModels;
using Windows.UI.Xaml.Controls;
namespace UWP_APP.Views
{
public sealed partial class MainPage : Page
{
public MainViewModel ViewModel { get; } = new MainViewModel();
public MainPage()
{
InitializeComponent();
string filePath = #"D:\example.xlsm";
if (File.Exists(filePath))
{
int a = 1;
}
else
{
int a = 0;
}
}

Does anyone know why the File.Exists cannot detect the file?
UWP app is running in sandbox, because File.Exists is System.IO api. So it could not work for accessing file except ApplicationData.Current.LocalFolder. If you do want to check if the file exist in the specific path, we suggest you add broadFileSystemAccess capability and enable in the system file access setting. This capability works for APIs in the Windows.Storage namespace.
And using the flolowing method to check if the file exist.
try
{
var file = StorageFile.GetFileFromPathAsync(#"C:\Users\Karan\OneDrive\Desktop\2010.pdf");
if (file != null)
{
isExist = true;
}
}
catch (Exception)
{
isExist = false;
}

Access Denied when opening folder in UWP app

I have a simple UWP app that I want to open a folder to access all the files in with. I'm using the stock example code from Microsoft for how to make a folder picker in UWP. However, after picking the folder (any folder) and trying to access it I always get this exception:
System.UnauthorizedAccessException
HResult=0x80070005
Message=Access to the path 'T:\temp' is denied.
Source=System.IO.FileSystem
StackTrace:
at System.IO.Enumeration.FileSystemEnumerator`1.CreateDirectoryHandle(String path, Boolean ignoreNotFound)
at System.IO.Enumeration.FileSystemEnumerator`1..ctor(String directory, EnumerationOptions options)
at System.IO.Enumeration.FileSystemEnumerable`1..ctor(String directory, FindTransform transform, EnumerationOptions options)
at System.IO.Enumeration.FileSystemEnumerableFactory.FileInfos(String directory, String expression, EnumerationOptions options)
at System.IO.DirectoryInfo.InternalEnumerateInfos(String path, String searchPattern, SearchTarget searchTarget, EnumerationOptions options)
at System.IO.DirectoryInfo.EnumerateFiles()
at ShutterShock.MainPage.<Button_Click>d__1.MoveNext() in C:\Users\nixca\source\repos\ShutterShock\ShutterShock\MainPage.xaml.cs:line 37
Mainpage.xaml.cs:
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices.WindowsRuntime;
using System.Threading.Tasks;
using Windows.Foundation;
using Windows.Foundation.Collections;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Controls.Primitives;
using Windows.UI.Xaml.Data;
using Windows.UI.Xaml.Input;
using Windows.UI.Xaml.Media;
using Windows.UI.Xaml.Navigation;
// The Blank Page item template is documented at https://go.microsoft.com/fwlink/?LinkId=402352&clcid=0x409
namespace ShutterShock
{
/// <summary>
/// An empty page that can be used on its own or navigated to within a Frame.
/// </summary>
public sealed partial class MainPage : Page
{
public MainPage()
{
this.InitializeComponent();
}
private async void Button_Click(object sender, RoutedEventArgs e)
{
string path = await GetOpenLocation();
var boop = new DirectoryInfo(path);
boop.EnumerateFiles();
}
async Task<string> GetOpenLocation()
{
string returnText;
var folderPicker = new Windows.Storage.Pickers.FolderPicker();
folderPicker.SuggestedStartLocation = Windows.Storage.Pickers.PickerLocationId.Desktop;
folderPicker.FileTypeFilter.Add("*");
Windows.Storage.StorageFolder folder = await folderPicker.PickSingleFolderAsync();
if (folder != null)
{
// Application now has read/write access to all contents in the picked folder
// (including other sub-folder contents)
Windows.Storage.AccessCache.StorageApplicationPermissions.FutureAccessList.Add(folder);
returnText = folder.Path;
}
else
{
returnText = "Operation cancelled."; //todo make this an exception, catch that exception
}
return returnText;
}
}
}
I get the exception on the "boop.EnumerateFiles();" line.

So of course right after posting this it came to me, but I'll leave this up because I didn't actually find an answer anywhere before asking. The Microsoft example is dumb, and unless all you want is the path of the folder, returning the path is useless. The UWP filepicker doesn't actually grant you System.IO level access to the folder, all it gives you is a StorageFolder you can work on. If you want to do anything useful, you need to return the StorageFolder object, you can use that to actually work on files. This is probably obvious to people who actually know what they're doing.

If you wan to get all files in a selected folder, then you can use folder.GetFilesAsync().
var folderPicker = new Windows.Storage.Pickers.FolderPicker();
folderPicker.SuggestedStartLocation = Windows.Storage.Pickers.PickerLocationId.Desktop;
folderPicker.FileTypeFilter.Add("*");
StorageFolder folder = await folderPicker.PickSingleFolderAsync();
if (folder != null)
{
var files = await folder.GetFilesAsync();
foreach(var file in files)
{
Debug.WriteLine(file.Path);
}
}
Here is the my result.

CopyAsync method not working in my application

I am writing code to copy an mp3 file into the local folder of an application. I am trying to use the CopyAsync method to do this, but a red squiggly line appears underneath this method and I'm unsure of how to fix it. The error specifies that there is no accessible extension method. It then advises if I'm missing an assembly reference or a user directive.
I've found extensive information on this method through Microsoft, so I know it's possible. I'm brand new to building apps in C#, so I am not quite sure how to fix it.
My code is included below:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Windows.Storage;
namespace MusicLibraryTest
{
public static class LibraryHelper
{
public static async void ChooseMusic()
{
//Music Library is opened on user's computer and displays all available mp3 files
var picker = new Windows.Storage.Pickers.FileOpenPicker
{
ViewMode = Windows.Storage.Pickers.PickerViewMode.Thumbnail,
SuggestedStartLocation =
Windows.Storage.Pickers.PickerLocationId.MusicLibrary
};
picker.FileTypeFilter.Add(".mp3");
//File is copied to local folder for use in music library
var file = picker.PickSingleFileAsync();
if (file != null)
{
await file.CopyAsync(ApplicationData.Current.LocalFolder);
}
}

Change this line:
var file = picker.PickSingleFileAsync();
To
var file = await picker.PickSingleFileAsync();
You're calling an async method that should be awaited.

Xamarin/Android - Issue reading locally stored photo from camera - no read access

I'm trying to create a simple test app to take photos in Android, using Xamarin. When I get this app working (or so I hope), i'll use the code in a real app that I'm working on. I'm using the following recipe from Xamarin as my basis:
http://docs.xamarin.com/recipes/android/other_ux/camera_intent/take_a_picture_and_save_using_camera_app/
The major difference is that I need to store images locally, and not on the SD card. I'm able to successfully take a picture (with the Android simulator). I can see the file in the file structure using ADB and can successfully copy and open the file on my PC. However, I'm unsuccessfull in accessing the file in the app, probably due to user rights.
Please note that I was successfull in creating my own .txt files, and reading them back using either System.IO and Java.IO.
Please review the following code. My app crashes when using "System.IO.File.ReadAllText" and gives me "Access to the path "/data/data/CameraAppDemo.CameraAppDemo/files/photo.jpg" is denied.". And whatever I try (absolute, relative paths, uri's), objBitmap is always null.
ADB says that "photo.jpg" has -rwxrwx--- rights, and though I'm not entirely sure, I think that should be more than sufficient
On the other hand, maybe the intent still has a lock on "photo.jpg"? Or something else is going on...
And one final note, I'm using System.IO.File.ReadAllText just for testing purposes. I experimented with stream readers as well, but with the same result. Also, though I believe this step is unnecessary, I enabled "WriteExternalStore" in the Manifest
namespace CameraAppDemo
{
using System;
using System.Collections.Generic;
using Android.App;
using Android.Content;
using Android.Content.PM;
using Android.Graphics;
using Android.OS;
using Android.Provider;
using Android.Widget;
using Java.IO;
using Environment = Android.OS.Environment;
using Uri = Android.Net.Uri;
[Activity(Label = "Camera App Demo", MainLauncher = true)]
public class MainActivity : Activity
{
private File _file;
private string _basePath;
private ImageView _imageView;
protected override void OnActivityResult(int requestCode, Result resultCode, Intent data)
{
base.OnActivityResult(requestCode, resultCode, data);
var objBitmap = BitmapFactory.DecodeFile(_file.AbsolutePath) ;
Console.WriteLine ("objBitmap = null : " + (objBitmap == null).ToString ());
var strOutput = System.IO.File.ReadAllText (FileManager.BasePath + "/photo.jpg");
Console.WriteLine (strOutput);
}
protected override void OnCreate(Bundle bundle)
{
base.OnCreate(bundle);
SetContentView(Resource.Layout.Main);
FileManager.SetupFolderStructure();
if (IsThereAnAppToTakePictures())
{
Button button = FindViewById<Button>(Resource.Id.myButton);
_imageView = FindViewById<ImageView>(Resource.Id.imageView1);
button.Click += TakeAPicture;
}
}
private bool IsThereAnAppToTakePictures()
{
Intent intent = new Intent(MediaStore.ActionImageCapture);
IList<ResolveInfo> availableActivities = PackageManager.QueryIntentActivities(intent, PackageInfoFlags.MatchDefaultOnly);
return availableActivities != null && availableActivities.Count > 0;
}
private void TakeAPicture(object sender, EventArgs eventArgs)
{
System.IO.Directory.Delete (FileManager.BasePath, true);
_basePath = FileManager.BasePath;
_file = new Java.IO.File (_basePath, "photo.jpg");
Intent intent = new Intent(MediaStore.ActionImageCapture);
intent.PutExtra(MediaStore.ExtraOutput, Uri.FromFile(_file));
StartActivityForResult(intent, 0);
}
}
}
//Part of the FileManager class:
using System;
using System.IO;
using System.Runtime.Serialization.Formatters.Binary;
using Android.Graphics;
namespace CameraAppDemo
{
public class FileManager
{
public static string BasePath {
get {
var libraryPath = Environment.GetFolderPath (Environment.SpecialFolder.Personal);
if (Directory.Exists (libraryPath) == false) {
Directory.CreateDirectory (libraryPath);
}
return libraryPath;
}
}
}
}
==== Edit ====
It seems that I'm simply not able to read the file. As an ex-webdeveloper, I'm fairly new to programming for mobile, let alone the combo of C# and Java and I'm still learning a lot.
Anyway, I added the following lines:
Console.WriteLine("Setting file :" + _file.SetReadable (true));
Console.WriteLine("Can read :" + _file.CanRead());
Both cases return False. I can't read the file, and I am unable to give read access.
So, any ideas? Is this by design? Can I tell the Intent for taking images to give me read access, or is there another workaround?
If everything fails, I'm hoping to workaround the problem by saving to the SD card first and then copying the file to the local filesystem. But that's something I rather would not do; I can't guarantee that the end users have an SD card, and the pictures should not be deleted by accident.