I have read the two other questions on SO regarding this and I wanted to know if there is a good solution for that now / best practice.
Long story short, we use an SDK which is written natively and we've wrapped it so that it works on Xamarin.Android and Xamarin.iOS. It has asynchronous callback methods. I need to call a method in the shared code when a callback is received in the Android project for instance.
There's a lot of info for doing the opposite - using DependencyService. How about in my scenario? Does anyone have experience with an app like this and what's the best approach to keep code clean and do this using MVVM?
The options I know are:
Using a static App instance - this is what we currently do.
MessagingCenter
Anything else?
Actually I've never seen anyone recommend usage of MessagingCenter for anything else than communication between ViewModels so I am not sure it is recommended here. Also, I need to know the sender object type so I need a reference to the class in the platform specific project.
I would recommend you to use messagingCenter to pass data or call method between shared project and platform project. You can just send a new object instead of the class in the platform specific project.
Also, have a look at using eventhandler as I mentioned in this answer may help someone who want to call from the shared project into the platform specific one.
BTW, I mean you can even pass an object as TSender if it is not necessary to use:
MessagingCenter.Send<Object>(new object(), "Hi");
MessagingCenter.Subscribe<Object>(new object(), "Hi", (sender) =>
{
// Do something whenever the "Hi" message is received
});
Related
I have some plugin's which are basically input and output type definitions. I have a generic controller which i can add to the mvc pipeline. All works fine.
but I'm having trouble setting the api version on this generic controller. I know you can set this based upon an attribute on top of the controller class. But since you can't have this dynamic (attribute) don't allow it, i have no way to set the version for each instance of the generic controller.
Currently i just compile the controller for each instance on runtime and register i using the roslyn compiler.
is there a way to set the api-version somewhere in the pipeline of registering controllers in the mvc pipeline and endup with different api versions endpoints.
This can be achieved by using the Conventions API. It was designed to support this exact type of scenario:
https://github.com/microsoft/aspnet-api-versioning/wiki/API-Version-Conventions
This will only work on closed-generics, but it shouldn't be too much work to make that happen. Here's a couple of basic examples:
// typed, closed generic
options.Conventions.Controller<GenericController<PlugIn1>>().HasApiVersion(1,0);
// untyped, closed generic
var controllerType = typeof(GenericController<>).MakeGenericType(new []{typeof(PlugIn1)});
options.Conventions.Controller(controllerType).HasApiVersion(1,0);
You can also author your own custom conventions a la IControllerConvention. This approach could be used to version all controllers that inherit from GenericController<>. Then you just need to add it to the conventions like this:
options.Conventions.Add(new PlugInControllerConvention());
Hopefully that's enough to get you started. Feel free to ask more questions.
I have a Xamarin Forms Project. I have used Dependency Service to call the Platform specific method to fire a local notification on Android and a Alert on iOS.
My problem is now, how to handle an action on both notification(android) and alert(iOS). Is it possible to call a method of the shared project from the android or iOS project?
Do I need another approach? Does someone know what I have to do?
Just for clarification, I know how the ordinary dependency services works i.e. Call a method on android or iOS from the shared project!
I believe I had a similar scenario on my app. If you want to push something from your platform methods to your PCL you would need to make use of call backs and event delegates.
In Interface PCL:
event OnMessageHandlerCallback OnMessageEvent;
event OnErrorHandlerCallBack OnErrorEvent;
In Platform specific Class inheriting interface:
private OnMessageHandlerCallback callback = null;
private OnErrorHandlerCallBack errorCallBack = null;
public event OnMessageHandlerCallback OnMessageEvent;
public event OnErrorHandlerCallBack OnErrorEvent;
Have you tried just calling the method from your native project...? No special patterns necessary. The native iOS and Android projects have a direct reference to your shared project, so it can call the method directly.
How to call a Javascript function (and register a callback function to be executed after the method execution from web view is done) inside an webview on nativescript?
First the bad new, nothing is "built" in to do this. This requires you to add some code to communicate back from the webview. In the nativescript-webworkers plugins that I wrote; the way I did it was I used the onJsConfirm function on Android. On iOS I used the userContentControllerDidReceiveScriptMessage callback to communicate back. If you want to develop your own code; just grab a copy of my webworkers plugin and you can see the way to do it.
Now to the good news, is that it appears there is already a plugin called "nativescript-webview-interface" which gives you this facility so you don't have to build all that binding code yourself. It looks like all you need to do is include it and you will have bi-directional communications with your webview on both iOS and Android.
Note; to see if a plugin exists in the NativeScript community; your best bet is to look on http://plugins.nativescript.rocks, that is how I found out about the above listed plugin.
I am totally new in developing with Xamarin and I try to use the MvvmCross library in a shared project for all platforms. It seems that I succesfully added the libraries in each project, but now I am confused how to start. I tried to follow the documentation, but I think I didnt understand it right. I can use the CreatableTypes Method, but there are no EndingWith or the other Methods from the documentation. The examples that I found are mostly about PCL. I even dont know if this is a version problem or if I missed something important at all. Any hint or link would be helpfull.
First of all be careful what informations you read, always check the date or you will waste your time with some articles which are outdated. The most important ressources are prolly the official sample: https://github.com/MvvmCross/MvvmCross-Samples
Normally you use the PCL for all the background stuffand there should be some class like this https://github.com/MvvmCross/MvvmCross-Samples/blob/master/TipCalc/TipCalc.Core/App.cs . In this class you should be able to register all your services like this for IoC:
public override void Initialize()
{
CreatableTypes().EndingWith("Service").AsInterfaces().RegisterAsSingleton();
And then MVVMCross automatically takes care of initializing it, if you do a constructor injection in the ViewModel as a Example...
public MainViewModel(IPreferenceService preferenceService)
{
// Do Something here with the Service
}
...and you just need to call to show it with it connected view:
ShowViewModel<MainViewModel>();
So basically try to understand the samples first, i think TipCalc is still mostly up to date, atleast it is MVVMCross 4.0 https://github.com/MvvmCross/MvvmCross-Samples/tree/master/TipCalc
I'm looking at https://github.com/XLabs/Xamarin-Forms-Labs/blob/master/Samples/XLabs.Sample/ViewModel/CameraViewModel.cs to try and get the camera available to my app.
I have this setup the same, but when I run my app the iOS app that calls my PCL is giving the error:
IResolver has not been set. Please set it by calling Resolver.SetResolver(resolver) method.
I don't know what this means or what exact code I need. I don't use IOC at all and I don't much care about it but I just want this camera to be available to my PCL. How can I get this camera available to my PCL when I'm not using MVC here.
If you wish to use the ViewModel then modify the constructor to take in IMediaPicker:
https://github.com/XLabs/Xamarin-Forms-Labs/blob/master/Samples/XLabs.Sample/ViewModel/CameraViewModel.cs#L62
public CameraViewModel(IMediaPicker mediaPicker)
{
this._mediaPicker = mediaPicker;
}
Remove the Setup function:
https://github.com/XLabs/Xamarin-Forms-Labs/blob/master/Samples/XLabs.Sample/ViewModel/CameraViewModel.cs#L156-L167
How you get the IMediaPicker implementation to PCL is up to you. IoC is the preferred (and easy) way but you can use other patterns as well. One would be to define a static Func<IMediaPicker> property on the ViewModel and set it in the platform specific projects.
IoC container is the easiest and quickest way to get it done and it would as simple as adding these lines at the application startup (e.g. AppDelegate's FinishedLaunching method):
var container = new SimpleContainer();
container.Register<IMediaPicker, MediaPicker>();
Resolver.SetResolver(container.GetResolver());