iOS main navigation is the tab bar at the bottom and Android recently launched the bottom navigation. Normally the search is contextual to the screen you are on, and the entry point is positioned on the top right for iOS and Android, but what if you need a search that searches through your full app. So a real global search. Is it a good idea to put it in the bottom navigation (Android), tab bar (iOS)?
If I look at the guidelines, they both (Android and iOS) recommend to put the main navigation elements there with a maximum of 5 elements. In the app we are building the search is a key feature and needs to search over the full app.
On iOS I saw that the Appstore app, Instagram app and Pinterest app are putting the search in the tab bar. On Android, while the bottom navigation is new, I didn't find any examples.
What is the preferred placement for a global search bar?