[t-sauer]

There is a common way to go back (swipe from the left edge of the screen). Some apps just don't integrate well and ignore the platform patterns.

[bayindirh]

I believe swiping from left to right is common for both Android and iOS.

[pndy]

Android has both a swipe gesture or a widget that simulates buttons that used to be at the bottom of the screen

[bayindirh]

...and iOS has both an arrow at the top left and a swipe gesture. I can't see how they are that different.