Xamarin.Forms自定义控件库

Question

How can i create custom control library based on Xamrin.Forms with my custom controls and platform specified code ? I need to make module architecture with posibility to add some modules with platform specified code.

Answer 1

Everything you're describing is already accounted for in the Xamarin.Forms framework. Specifically, there is support for UI controls with platform-specific renderers and for non-ui code using the DependencyService. In both cases, you define common data structures, interfaces and View subclasses in a common library that references Xamarin.Forms and targets the Android/iOS/Windows Phone platforms, and provide platform-specific code in assemblies that specifically target the various platforms.

In the case of the UI controls, you create platform-specific renderers (aka "Custom Renderers") and register them with the Xamarin Forms runtime using the ExportRenderer attribute. In practice, the way this should work is that the control from the "API assembly" (from here on, I'll use the term Jason Smith uses for it: the "model") is used to capture any configuration or data binding, and the custom renderer then uses the data contained in the model to determine how the native controls looks/behaves. It's important to note that there are effectively two instances here: the model instance, which is what the Xamarin Forms view is using as an API surface to control the actual control's behavior, and the renderer instance, which is what's actually drawing the UI. If there is any data binding, you'll want the renderer to watch the model's bindable properties for changes so the UI can reflect the state of the model. This topic is described in much more detail in Xamarin's docs for Custom Renderers .

In the case of non-UI code ("headless" functionality such as geolocation, sensors, etc.) you can use the DependencyService. Similar to the UI controls, you define an abstract API (expressed as interfaces) that exists in the "API Assembly" to provide a platform-independent way to access the functionality and you provide an implementation for each supported platform that is registered using the DependencyService attribute. In practice, you can think of the DependencyService as a Dependency Injection container that is automatically populated using that attribute. Again, this topic is fully covered in the Xamarin docs for the DependencyService .