Hi, if you know swift, xcode, have great UI skills then this one would be easy.
Here's what we want to do, please let us know how long and how much you think it would cost:
1) Button in app takes a photo (so would need access to camera and photo library)
2) picture comes up - and you can highlight a small area (user can decide how big dynamically such as drawing on it to define the borders) on the photo (you can zoom in if you want to get more control over the area)
3) a colour slider allows you to change the colour in that area only - the upper and lower bounds of the colour should be defined as constants (all constants in their own file). Bonus if you can figure out how to keep the texture of the object but just change it's color
4) Allows you to save new picture or overwrite existing picture
Try to keep it to as few external libraries as possible. Should not be bloated
Also, all libraries and techniques used should be open source and royalty/license free
** All constants / variables should be in their own file
** Code should be documented
** Should be straight forward
** UI should be clean, following Apple's guidelines and flat.
Once this project is done, there will be opportunities for more work. Thank you.