Inspired by Microsoft's Picture Login, I made this library which can be downloaded here together with a small demo project that runs on iPhone and iPad. KSPictureLoginController allows you to let users draw a gesture (= a path) or taps on top of an image. You can then save the drawn gesture (XML serialization is built in) and pass it back into the controller for verification. If the gesture is redrawn precisely enough, you'll get a callback.
The code is highly customizable and adjustable.
Note about the performance
I have just retested the code on the iOS 7.1 Simulator and for some reason the performance is really bad. However the experience on the device is totally different. Everything works really smooth.
Find the code on Github
You can find a demo video on Youtube
Copyright (C) 2013 Krumelur Soft (René Ruppert)
This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>.