Somewhat designed for strife…
The thinking behind Designer impresses. You drop bitmap art onto an OS X window and can preview it on any iOS devices running the free Designer Preview app. There’s also a strong feature set, with the Mac app providing controls for orientation and toggling the iOS keyboard.
There are layers, enabling you to move components around, and live updating. In theory, this means if you update and re-save a previewed file in a Mac app, Designer updates the previews on your devices. The reality is less impressive.
We found updates didn’t always take, and when they did there was ghosting during supposed refreshes. Images had to be at 144dpi for Retina or they scaled oddly. Re-saved items also autocentred (and moved) unless they were the exact dimensions of the target device.
Perhaps we expected too much. It’s a reasonable timesaver, but the current version is flawed.
Verdict:
Work within its limitations and this is an adequate iOS preview app, but it should have been great.

Price: £2.99
Developer: Pavel Kanzelsberger
OS: OS X 10.6+
Requires: At least one iOS device, local network