iphone app - children puzzle

We are developing a children application and would need a developer to assists with the programming. ‘Vehicle Puzzles’ is a simple application targeted towards children from 1 year and above. The screen will display different type of vehicles puzzles. Users may choose the level of difficulties from easy, medium to hard. Users may drag and drop the puzzle piece into a given box to try and solve the puzzle. Upon completing, screen will display the completed image with an applause sound. The first 5 vehicles will be free and there will be an in-app purchase to unlock the rest. In total, there will be about 20 different vehicle puzzles to be solved. Images and sounds will be provided for this application. Developer must have experience in successful application development and in particular, in app purchase functionality. You will also be required to test the application aggressively for bugs and be responsible for any updates due to programming error if required. I will keep 20% of the payment in milestone upon successful publishing of the app for a period of 14 days to ensure that the app is free of programming bugs. Please submit your best 3 apps that you have developed for consideration. We need for both iphone and ipad.