I am new in iPhone application development and currently working on .net (C#).
Please suggest the development platform to create iPhone application so I can adopt very soon.
Which is best among these:
Or any other tool that is not on the list.
Is it possible to develop iPhone application using .NET framework? I'm not sure; I think not.
It's not possible develop application for iPhone on Windows platform. You need official SDK and it's only for Mac OS X.
The official SDK is free but not open-source. All the tools necessary to build iPhone apps are free. HOWEVER you cannot put your apps on an iPhone or iPod Touch device without paying the $99 for the developer license. You can run the apps you build on the iPhone Simulator, which is an application that runs on your Mac. It looks and behaves pretty much like a real iPhone, minus a few obvious things (no GPS, no camera).
Go to http://developer.apple.com/iphone/ to get started.
XCode is the only development environment for iPhone and Objective C is the language it uses for this. You cannot use the .NET framework to build an iPhone app.
The SDK is free to download but you will need register (for free) with apple to get the SDK and all it initially lets you do is build and run apps in a software simulator environment; to put apps on a physical phone you need to buy a license (for $99) and go through a rather convoluted process to set up signing certificates.
The SDK and a variety of sample code and tutorials are all at the Apple iPhone developer site http://developer.apple.com/iphone/.
Unity looks very promising, but it's cost prohibitive for an indy programmer. I looked at this last week and for me to get the package I needed I'd have to drop down almost $3,000. You'd still have to use XCode to compile your app though.