Available in R3 2018 as part of the features set of the new and improved RadAutoCompleteView control, for more details on it refer to: https://docs.telerik.com/devtools/xamarin/controls/autocompleteview/autocompleteview-overview As to the concrete feature go to: https://docs.telerik.com/devtools/xamarin/controls/autocompleteview/autocompleteview-methods
There does not seem to be an easy way to modify the custom message shown when no result is found in the AutoComplete control. We can expose a property similar to the Watermark one. Edit: Avalable in R3 2017 SP release.
Currently the Text property can only be get. Expose it as setter as well.
Allow customers to easily take the user input and trigger custom searching algorithm and assign the results to the ItemSource of the AutoComplete. Available in R3 2018 release as part of the feature-set of the new and improved RadAutoCompleteView control, for more details refer to: https://docs.telerik.com/devtools/xamarin/controls/autocompleteview/autocompleteview-overview