Here is one of the most compact iOS compatible rowers money can buy. The Sunny SF-RW1205SMART Compact Rowing Machine has 12 levels of adjustable resistance. It comes with Bluetooth connectivity and an app that gives you access to over 1000 training videos and global tours. It also has a smartphone holder built-in.
The SF-RW1205SMART weighs only 22.4lb, so you can easily take it around. It has max weight capacity of 220lbs. You can assemble it in 15 minutes. You can also store it in small rooms when not in use.[where to get it]