After researching in Xamarin. Forms, I decided to use Application. Properties property. It looks like it is working just only if the app still remains alive. If I close the app and start it again the Application. Properties is empty. I have had a ton of problems with Application. Properties on Android. I highly suggest using Xamarin Settings plugin instead which I have never had any issues with.
It is persistent even when the app is closed. That being said Application. Properties is supposed to work even with you close the app. Not sure why it wouldn't but it does not surprise me either.
Current is the plugin class that will do the work but the example just creates a separate property to access it. So create a new file, lets call it SettingsImplementation :.
My own problem regarding this issue was due to me not explicitly saving the properties with the following line of code:. Learn more. Persistent Storage using Application.Could someone please clarify whether this collection is supposed to persist between runs of an App. I get a Systems. KeyNotFoundException when I try to read an element which existed on the previous run.
I should add, that I am running the IOS simulator in debug mode, in case that makes a difference. FredyWengerthank you for your reply and the link. This is just a XF issue for me at the moment, not Android specific.
KeyNotFoundException trying to set host. SavePropertiesAsync after making your changes. Available since XF 1. JeremyHerbison many thanks for your reply. I will try that. JeremyHerbison I've run into the same issue as well, except I am calling SavePropertiesAsync after each change and none of it persists between runs. MartHughTrevorAllen :. I have posted a real-life example, how I use the properties in my app including int in the similar thread of another user here:.
JeremyHerbison I am saving string values, but none seem to persist. I have also had trouble saving the properties a few weeks ago, even with the SavePropertiesAsync.
Persist Whatever You Want With Xamarin.Forms
I tried the same code again yesterday and suddenly it worked, even between app restarts. I don't know what fixed it maybe a Forms Update?
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Xamarin.Forms - Application Preferences Using Xamarin.Essentials
What is Xamarin. May in Xamarin. Tagged: xamarin. May MartHugh : It should work if you save the properties explicit. See also this thread to the same theme a short time ago: forums. If I do something like this Application.
Properties ["DataHost"]. ToString ; I can use the host variable and it contains the string "www. ToString ; and then rerun with the first line commented outI get a Systems. Have I misunderstood what you mean by saving explicitly?
I am a bit unsure on how to do this. If I do this I saw that there is a plugin called "Settings" that I might need to use instead in case there isn't a solution to this problem but I would prefer to work with my current code if possible. The Properties dictionary can only serialize primitive types for storage. Attempting to store other types such as List can fail silently. It means that you can't save List because it's not a primitive type of object.
You can serialize it to JSON string for example then it will work. Code example:. Note that yourList. ToString will not work in this case. More info here. Learn more. List does not get saved when I use Application. Asked 3 years, 5 months ago. Active 3 years, 5 months ago. Viewed 3k times. I am currently trying to save a list in Xamarin forms. SavePropertiesAsync ; When I then close the app and use this code I cannot reach this if statement.
ToString ; Carlos Rodrigez Carlos Rodrigez 8 8 silver badges 19 19 bronze badges. Active Oldest Votes. SerializeObject myList ; Application. EvZ EvZ HttpContent is not a primitive type, that's why it's not working. Serializing to JSON string is enough. I updated my answer with code example.
HttpContent is not a "primitive type". Seems to work now : Awesome. I am a bit unsure on how to get the value out now though, with this code: foreach var data in Application. You have a "String". Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name.In this article, you will learn how to use Application Preferences using Xamarin.
Essentials in Xamarin forms. Forms code runs on multiple platforms - each of which has its own filesystem. This means that reading and writing the files are most easily done using the native file APIs on each platform. Alternatively, embedded resources are a simpler solution to distribute data files with an app. Essentials API works with all Xamarin. Forms, Xamarin. Android, Xamarin.
Essentials overcomes the problem, so developers can access every native platform API using C. This plugin provides many APIs so initially, there is no need for more plugins for Xamarin.
Essentials plugin impacts your app's minimum size. One of the ways is called Shared Preferences. Shared Preferences allows you to save and retrieve the data in the form of a key-value pair. In order to use shared preferences, you have to call a method, getSharedPreferences ,that returns a SharedPreference instance pointing to the file that contains the values of preferences.
By using the Defaults System, the user can configure an app's behavior or styling to meet their preferences based on the design of the app. The methods and properties of this class support creating, deleting, enumerating, and traversing the container hierarchy. This can be accessed from anywhere in your Xamarin.
Forms code using Application. The Properties dictionary uses a string key and stores an object value. Forms project. Choose the Xamarin.The Application base class offers the following features, which are exposed in your projects default App subclass:.
Depending on which template you chose, the App class could be defined in one of two ways:. The MainPage property on the Application class sets the root page of the application. For example, you can create logic in your App class to display a different page depending on whether the user is logged in or not. The Application subclass has a static Properties dictionary which can be used to store data, in particular for use in the OnStartOnSleepand OnResume methods.
This can be accessed from anywhere in your Xamarin. Forms code using Application. The Properties dictionary uses a string key and stores an object value. For example, you could set a persistent "id" property anywhere in your code when an item is selected, in a page's OnDisappearing method, or in the OnSleep method like this:.
In the OnStart or OnResume methods you can then use this value to recreate the user's experience in some way. The Properties dictionary stores object s so you need to cast its value before using it. The Properties dictionary can only serialize primitive types for storage.
The Properties dictionary is saved to the device automatically. Data added to the dictionary will be available when the application returns from the background or even after it is restarted.
Forms 1. This is to allow you to save properties after important updates rather than risk them not getting serialized out due to a crash or being killed by the OS. Forms book chapters 615and 20and in the associated samples. This class is then instantiated in each platform-specific project and passed to the LoadApplication method which is where the MainPage is loaded and displayed to the user.
The code for each platform is shown in the following sections. The latest Xamarin. Forms solution templates already contain all this code, preconfigured for your app.I'll admit, until recently, I was blissfully unaware that Xamarin. Forms has a baked-in persistence mechanism in the form of a static IDictionary object in the App class.
You can use it for persistent storage of whatever you'd like and I'll get to how below. And it is perfect for storing things such as user preferences.
The Application class defines the Properties property as static. It also defines another property Currentwhich returns the current, running instance of the Application as static. Then to get at the Properties and all of the persistence that it provides, all one needs to do is acces App. Properties anywhere in their Xamarin. Forms application to get at the persisted storage. Essentially App. Properties is a global variable, available everywhere.
Whether you should use it within view models, or deep in your app is an architectural question - which I'll leave up to you! Reading data out of the App. Properties dictionary is the same as reading out of any regular dictionary that you're already used to. You want to first make sure the key exists in the dictionary - read the value out via the key if it does - then cast the value over to the type it should be. Again, much like reading data, writing data to the App.
Properties is the same as writing data to a normal dictionary. First you'll want to see if the key already exists, if not, use the Add function of the IDictionary. Because the App. It should be noted that adding or updating an entry in the App. Properties dictionary does not automatically persist it to permanent storage. The first is the Application object gives a function called SavePropertiesAsync.
This will force everything in the Properties dictionary to be written and is advisable to be called as soon as after something important is written to the dictionary. The second way the Properties dictionary gets persisted is to let Xamarin. Forms automatically do it. In the OnSleep function of the Application object - the contents of the Properties object will be persisted out. This means that whenever your app gets backgrounded, the contents of App.
Properties will be saved - this is a safety fall-back to make sure everything gets persisted and is there the next time your app is launched. There are a couple of gotchas that you need to be aware of in order to make the App. Properties persistence work for you - instead of you fighting it. Despite the face that App. You know, intstringdouble Luckily - there is something that is wonderful at representing an object as a primitive type And through the wonderful library of JSON.
Net - it's super easy to take any object graph, serialize it to JSON, and then persist it in the App.nqfhall.space Backgrounding - Rob Gibbens - Xamarin University Lightning Lecture
Properties dictionary. But with itThis article covers working with Application Storage to save app settings on the app in the Xamarin forms App. Introduction Xamarin. Forms code runs on multiple platforms -- each of which has its own filesystem. This means that reading and writing files are the most easily done tasks using native file APIs on each platform. Alternatively, embedded resources are also a simpler solution to distribute the data files with an app.
Application Storage Xamarin Android - Shared Preferences Android provides many ways of storing the data of an application. One of the ways is called Shared Preferences. Shared Preferences allow you to save and retrieve data in the form of key, value pair. In order to use shared preferences, you have to call a method getSharedPreferences that returns a SharedPreference instance pointing to the file that contains the values of preferences.
By using the Defaults System, the user can configure an app's behavior or styling to meet their preferences based on the design of the app. The methods and properties of this class support creating, deleting, enumerating, and traversing the container hierarchy. This can be accessed from anywhere in your Xamarin. Forms code using Application. The Properties dictionary uses a string key and stores an object value. Forms Project Start by creating a new Xamarin.
Forms project. You now have a basic Xamarin. Forms app. Click the Play button to try it out. Setting up the User Interface. Go to MainPage. Xaml and write the following code. Properties[ "ID" ]. Properties[ "Name" ]. Properties[ "IsMVP" ]. I hope you have understood how to use Application Storage in Xamarin Forms.
Thanks for reading.
Xamarin.Forms App Class
Please share comments and feedback. View All. Forms - Working With Application Storage. Delpin Susai Raj Updated date Mar 08, Setting up a Xamarin. Store Value The Properties dictionary uses a string key and stores an object value. Get Value The Properties dictionary stores objects so you need to cast its value before using it.
Remove Value If you want to remove values, you can remove them. Free Demo.