All the credits for solution described in this post goes my friend qbus. He saved few hours of my life and my sanity ;-)

In Xamarin.Forms application I have a button with non-default styling (defined in XAML). Target platforms are iOS and Android. Enabled and disabled states should obviously be distinguished with colors.

The most straightforward solution that makes use of Data Triggers works well for Android. For some reason it doesn’t want to work properly on iOS. If the button is initially disabled it displays correctly in this state but after changing IsEnabled to true and then back to false it does not anymore. Interestingly the background taken from style setter is good, but not the text color property.

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ModernHttpClient is a great wrapper around native HTTP clients offered by Xamarin. It wraps NSURLSession on iOS and OkHttp on Android. As it deals pretty well with SSL/TLS stack (especially in uncommon scenarios) it’s often used instead of built-in types. I switched to ModernHttpClient because of weird errors on connections to the preproduction environment in Android.

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When you build a multi-platform application in .NET, especially for the mobile, you typically choose between two approaches. One is to code the shared UI layer commonly with Xamarin.Forms (you will still need to have some parts to be placed in platform projects, like custom renderers or providers). The second is to put the entire UI code in platform-specific projects. In this approach you can use the full power of each platform features (like fragments on Android). Both solutions allow for sharing common business logic between all the platforms. On the other hand full implementation of MVVM pattern in the second approach can be tricky and time consuming. The solution is to use 3rd party library; and here comes the MvvmCross. It covers many more areas than the pure MVVM pattern:

  • cross-platform plug-ins,
  • platform-specific helpers (i.e. Android recycler views with grouping or iOS table views with simplified customization API),
  • IoC and messaging infrastructure.

Thanks to the consistent design, all the plugins and extensions, it can seriously speed-up building UI-intensive cross-platform projects. And it still allows you to take all the benefits provided by MVVM design pattern.

Now let’s see how to make Ninject and MvvmCross work together on your project.

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Have you ever encountered an error: Error executing task BuildApk: .../bin/packaged_resources does not exist? If so you probably know that solving this issue can be sometimes quite tricky. It may be hard to track when and where the true bug was introduced in the code base. Although some suggestions can be found on the Xamarin Forum the solution usually differ case by case.

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As it’s mentioned in MVVMCross documentation Android is quite specific in terms of navigation requirements. The entry point is statically indicated by MainLauncher = true attribute parameter on the activity. On rest of the platforms, specifically on iOS, this can be done dynamically by implementing IMvxAppStart class for registration in MvxApplication.Initialize().

To achieve this MVVMCross introduce a special lightweight type of activity - IMvxAndroidSplashScreenActivity. Unfortunately the default implementation does not support the features from MvvmCross.Droid.Support.V7.AppCompat like vector images or material design themes.

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