I'm trying to read a Json file for my mobile app in Xamarin Studio, but it throws me an error
can not find the file
While I try the same in Console Application every thing is all right.
I'm trying reading the file this way:
string Jason = File.ReadAllText(#"C:\Folder\file.txt")
This information is taken from Xam160 Class from Xamarin University. Within mobile application the platform generates a isolated folder area specifically for your App. These are the preferred locations to store files specific to your App with AppHome representing the Root of your sandboxed area.
Android - AppHome/files
iOS - AppHome/Lirbrary/[subdirectory]
Windows Phone - AppHome\Local
To Access these paths you can work with the Environment.SpecialFolder Enumeration to access these locations with the Environment.GetFolder() Method.
//Android
string path = Environment.GetFolderPath(Environment.SpecialFolder.Personal);
//iOS
string docFolder = Environment.GetFolderPath(Environment.SpecialFolder.Personal);
string libFolder = System.IO.Path.Combine(docFolder,"..","Library");
// Windows has different implementation. GetFolder Path with throw exception on windows.
string path = Windows.Storage.ApplicationData.Current.LocalFolder.Path;
Each of these will get you access to the path you need to be able to read and write files locally on which platform you are on.
Related
I am building a Hololens Unity App and I am trying to load in connection certification files for a server I connect to in my app. There is a .crt and a .pfx file located at the Assets/StreamingAssets folder.
On the unity editor and when running the app on unity, the files are read correctly and the connection works.
Here is the Code:
X509Certificate caCert = new X509Certificate(Application.streamingAssetsPath + "/a.crt");
UnityEngine.Debug.Log(caCert + "TRUE");
X509Certificate2 clientCert = new X509Certificate2(Application.streamingAssetsPath + "/b.pfx");
UnityEngine.Debug.Log(clientCert + "TRUE");
MqttClient client = new MqttClient(broker, 8883, true, caCert, clientCert, MqttSslProtocols.TLSv1_2, MyRemoteCertificateValidationCallback);
My problem is that when I deploy this to thew hololens, I am unable to access the .pfx file and it does not appear to be deployed onto the hololens saying that the file is not found (but the .crt file and the rest of the folder are there...).
Another issue I have:
I have also manually entered the certifications into the hololens' c: drive and they show up in its file explorer. I do not know how to access them, since that would be an easier workaround if I could just find the location of the file on the hololens drive itself and load it in from my app.
If anyone has experience with loading in files onto hololens unity-based applications and can help me with loading in the files while using the application on the hololens2, I would appreciate it very much.
Since HoloLens APP is a UWP APP, so make sure you use backslashes () as a path separator character. And the best practice is to use Path.Combine() instead of constructing paths yourself. It will take care of all the platform specific prefixes, appendices, delimiters, slashes, backslashes etc.
X509Certificate caCert = new X509Certificate(Application.streamingAssetsPath + "/a.crt");
=>
X509Certificate caCert = new X509Certificate(Path.Combine(Application.streamingAssetsPath + "a.crt"));
I just want to log to console and to a log file, using a standard TraceSource, in my Xamarin app that will run on UWP, Mac OS X, iOS and Android. I'm developing/debugging on UWP.
TraceSource, TraceListener, and TextWriterTraceListener are indeed all available in .Net Standard library, so perhaps I'm setting it up incorrectly? Most places on the Internet insist on setting up trace listeners in an app.config file, but this is not applicable nor possible for Xamarin apps. So here is my logging initialization code, mostly based on an example in Microsoft docs:
private void SetupLogging()
{
Trace.Listeners.Add(new TextWriterTraceListener(Console.Out, "consoleTraceListener"));
string logFilePath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.CommonApplicationData), "Application.log");
if (!File.Exists(logFilePath)) File.Create(logFilePath);
var logFileTraceListener = new TextWriterTraceListener(logFilePath, "logFileTraceListener");
Trace.Listeners.Add(logFileTraceListener);
Trace.Write("Test");
Trace.TraceInformation("Logging Initialized. Log file location: " + logFilePath);
Trace.Flush();
}
When I run this in a Xamarin UWP app, a file is created but nothing is written to it, nor can I find anything in the Output of the program (there is no ConsoleTraceListener so I'm trying to write a TextWriterTraceListener to Console.Out). Can someone provide a working example for Xamarin? (I haven't tried the Android or iOS apps yet; want to get UWP on the local machine working first.)
The problem is that you passed wrong string parameter to TextWriterTraceListener method. Please try to pass Stream parameter. You could use following code directly. by the way, you'd better use LocalApplicationData SpecialFolder that could be accessed successfully within uwp.
private void SetupLogging()
{
Trace.Listeners.Add(new TextWriterTraceListener(Console.Out, "consoleTraceListener"));
string logFilePath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData), "Application.log");
if (!File.Exists(logFilePath))
{
File.Create(logFilePath);
}
var logFileTraceListener = new TextWriterTraceListener(File.Open(logFilePath,FileMode.Open), "logFileTraceListener");
Trace.Listeners.Add(logFileTraceListener);
Trace.Write("Test");
Trace.TraceInformation("Logging Initialized. Log file location: " + logFilePath);
Trace.Flush();
}
I have a simple Xamarin Forms app. I've now got a simple POCO object (eg. User instance or an list of the most recent tweets or orders or whatever).
How can I store this object locally to the device? Lets imagine I serialize it as JSON.
Also, how secure is this data? Is it part of Keychains, etc? Auto backed up?
cheers!
You have a couple options.
SQLite. This option is cross-platform and works well if you have a lot of data. You get the added bonus of transaction support and async support as well. EDIT: In the past I suggested using SQLite.Net-PCL. Due to issues involving Android 7.0 support (and an apparent sunsetting of support) I now recommend making use of the project that was originally forked from: sqlite-net
Local storage. There's a great nuget that supports cross-platform storage. For more information see PCLStorage
There's also Application.Current.Properties implemented in Xamarin.Forms that allow simple Key-Value pairs of data.
I think you'll have to investigate and find out which route serves your needs best.
As far as security, that depends on where you put your data on each device. Android stores app data in a secure app folder by default (not all that secure if you're rooted). iOS has several different folders for data storage based on different needs. Read more here: iOS Data Storage
Another option is the Xamarin Forms settings plugin.
E.g. If you need to store a user instance, just serialize it to json when storing and deserialize it when reading.
Uses the native settings management
Android: SharedPreferences
iOS: NSUserDefaults
Windows Phone: IsolatedStorageSettings
Windows RT / UWP: ApplicationDataContainer
public User CurrentUser
{
get
{
User user = null;
var serializedUser = CrossSettings.Current.GetValueOrDefault<string>(UserKey);
if (serializedUser != null)
{
user = JsonConvert.DeserializeObject<User>(serializedUser);
}
return user;
}
set
{
CrossSettings.Current.AddOrUpdateValue(UserKey, JsonConvert.SerializeObject(value));
}
}
EDIT:
There is a new solution for this. Just use Xamarin.Essentials.
Preferences.Set(UserKey, JsonConvert.SerializeObject(value));
var user= JsonConvert.DeserializeObject<User>(Preferences.Get(UserKey, "default_value");
Please use Xamarin.Essentials
The Preferences class helps to store application preferences in a key/value store.
To save a value:
Preferences.Set("my_key", "my_value");
To get a value:
var myValue = Preferences.Get("my_key", "default_value");
If you want to store a simple value, such as a string, follow this Example code.
setting the value of the "totalSeats.Text" to the "SeatNumbers" key from page1
Application.Current.Properties["SeatNumbers"] = totalSeats.Text;
await Application.Current.SavePropertiesAsync();
then, you can simply get the value from any other page (page2)
var value = Application.Current.Properties["SeatNumbers"].ToString();
Additionally, you can set that value to another Label or Entry etc.
SeatNumbersEntry.Text = value;
If it's Key value(one value) data storage, follow below code
Application.Current.Properties["AppNumber"] = "123"
await Application.Current.SavePropertiesAsync();
Getting the same value
var value = Application.Current.Properties["AppNumber"];
I am going through http://developer.xamarin.com/guides/cross-platform/xamarin-forms/working-with/images/
and trying to get the Local Images working with Android however I am experiencing some issues when attempting to do something in normal monodroid just as a further test. I'm using a SharedProject, just for reference.
I have added the test image at Resources/drawable (test1.png), and also setting the Build Action as AndroidResource as it describes, and if I do the following in Xamarin.Forms it works:-
Xamarin.Forms.Image myimage = new Image();
myimage.Source = ImageSource.FromFile("test1.png");
However, if I try and retrieve the same file via the following it comes back as null.
Android.Graphics.Bitmap objBitmapImage = Android.Graphics.BitmapFactory.DecodeFile("test1.png")
Does anyone know why this is null and how to correct?
The Xamarin.Forms FileImageSource has a fallback mode as it covers two different scenarios.
First it will check whether the file exists in the file system via the BitmapFactory.DecodeFile.
Should the file not exist as specified in the File property, then it will use BitmapFactory.DecodeResource to try and load the resource content as a secondary alternative.
FileImageSource for Android therefore isn't only just for files that exist in the file system but also for retrieving named resources also.
This link indicates that Android Resources are compiled into the application and therefore wouldn't be part of the file system as physical files.
Since test1.png is a Drawable you should use BitmapFactory.DecodeResource ()
string scr = "#drawable/test1.png";
ImageView iv = new ImageView(context);
Bitmap bm = BitmapFactory.DecodeFile(src);
if (bm != null)
iv.SetImageBitmap(bm);
I have an app that needs to include a links to a second app in the same phone.
If the app is not installed the link should point to the windows store to install it (that part is working fine).
But if the app is already installed the link should go straight to the app and open it. How can I do that?
The app has two versions one form WP7 and other from WP8. if the solution is different for them please point the difference.
Thanks for the help...
I believe a URI Association is what you want. You should be able to create a different association in your WP7 app and in your WP8 app, and handle them accordingly.
A URI association allows your app to automatically launch when another app launches a special URI.
Also note:
If you are interested only in launching your own apps, consider using
APIs from the Windows.Phone.Management.Deployment namespace. You can
use this API to check for other apps that you’ve published, and then
launch them if they’re installed.
You basically just need to update the WMAppManifest.xml file to include the URI Association and then listen for that URI. Example:
<Extensions>
<Protocol Name="contoso" NavUriFragment="encodedLaunchUri=%s" TaskID="_default" />
</Extensions>
Then you can use a custom URI Mapper to handle your association (full example in top link above):
public override Uri MapUri(Uri uri)
{
tempUri = System.Net.HttpUtility.UrlDecode(uri.ToString());
// URI association launch for contoso.
if (tempUri.Contains("contoso:ShowProducts?CategoryID="))
{
// Get the category ID (after "CategoryID=").
int categoryIdIndex = tempUri.IndexOf("CategoryID=") + 11;
string categoryId = tempUri.Substring(categoryIdIndex);
// Map the show products request to ShowProducts.xaml
return new Uri("/ShowProducts.xaml?CategoryID=" + categoryId, UriKind.Relative);
}
// Otherwise perform normal launch.
return uri;
}
Hope this helps!
Is the secondary app one that you have created? If so, do something like this:
IEnumerable<Package> packages = InstallationManager.FindPackagesForCurrentPublisher();
foreach (Package package in packages)
{
if (package.Id.ProductId.ToString().ToLower() == "product id of secondary app")
{
//Launch the app
package.Launch();
}
}
Make sure that your publisher ids match in the WMAppManifest for both apps.
If this secondary app was published by someone else, you'll need to use a custom Uri schema. The app needs to have this feature added by the developer, you can't just launch any app.