Google has guidelines published, which is prescribed how apps on Android should look like and how they should work. So notifications are always off, and stylistic elements from iOS not in the apps to be applied.
The guidelines are not mandatory on Android; Google approves the apps, not before them in the Android Market appear. However, the guidelines advice about how developers of apps that is on all Android hardware works well and a clear layout.
Google found the guidelines, because Android apps are now mostly different layouts, giving users more time to the interface of an app to learn. As developers in large numbers in the guidelines to follow, work apps, often in the same way, allowing users to know where they are, what function can find.
One of the points on which Google insists, is that there are no elements of other platforms should be acquired. This includes, inter alia to elements of iOS, such as the Back button at the top, the little arrows next to list items and the tab bar at the bottom. “When you the theme of interface elements want to customize, do it carefully and according to the guidelines of your own brand, not according to the conventions of a different platform,” warns Google.
Another point that Google wants to make is that developers must be careful with notifications. It could be that notifications are always off and need the app to do all the activity, a notification, because the notification bar cluttered.
The guidelines are aimed at Android 4.0 Ice Cream Sandwich, the new version of Googles mobile operating system, in which the interface has changed drastically. Google introduced never before as a guide to developers pointing out how the layout of apps can be designed.