iPhone app development is a pretty big problem for a small/medium business and any individual who has an amazing idea or business requirements and does not understand the dynamics of app development. Hence it is very important that an app designer and developer have previous on getting an app approved on the app store.
In my opinion there will be plenty of app developers who can display credentials that prove they are experienced but what is more important is creativity. The most important thing for any app to perform well in the saturated app store is a creative design and equally good development.
I contacted many app developers on freelance project websites and was unable to find a creative person or company to develop my gaming app. This was because I was busy at work and wanted a cost effective option to bring a gaming app I had in mind for some time. Finding a good app designer and developer is very difficult and time consuming; one of the biggest problems is that they don't work according to deadlines and if they do the completed app is full of inconsistencies or bugs. Additionally freelance app developers often refuse to release code to its owner upon finishing their work, most employers often ignore this important feature while negotiating terms of a deal considering it as "basic understanding" but it is important to mention code ownership while negotiating a deal. Other problems include project management and time management and it is important to get the basic compulsory out of the way as soon as possible. Remember while negotiating; always go for developers who will/can offer you money back guarantees, while hiring an app designer it is important to pay them after they design your home/splash page since that will make or break your app.
Another problem is security. Make sure that any contractor or freelancer you employ signs a 'non-disclosure' agreement. Remember your app idea may unique and you don't want anyone else taking advantage of it, a simple change in design/UI can allow anyone to copy your app idea and trust me copyright laws and court proceedings are full of loopholes that can be exposed very easily. It is essential that you trust your contractor and make all the necessary arrangements and make sure you don't leave anything especially the code which can be re-sold very easily and destroy your idea.
App development and design especially from freelance contractors is often difficult and risky, make sure you have covered your corners well.
I don't have the idea about freelance iPhone App Development now I will search about it.Thanks