Quite often, when taking pictures using iPhone, in ladscape, it saved as portrait.
This happened especially when trying to capture image from a table, where iPhone is positioned with camera facing down.
The solution: before taking picture, position iPhone upright, turn the camera on, then turn the iPhone to landscape, point to your object, and shoot.
It's simple, just need a little training. You need not using other tools or go back to your desktop to rotate photos you took from iPhone no more.
-- Post From My iPhone