First of all find how advanced iOS app you want to be developed. In order to do you need to check the skill sets & experience of iOS App developer and these can be categorized into junior, middle and senior iOS app developer. 
If it's native application development then find out whether you want to go for Objective-C language or Swift technology (latest) on XCode platform. That means iOS developer should have the sound knowledge of Core Data framework and Xcode IDE. 
If you are going to hire senior iOS app developer, then your application development will be really easy. This is because iOS developer already worked on several projects and have mastered the skills. In another case if you want to launch your app in short duration, then team hiring would be the ideal solution. 
I am sure after seeing these tips to hire iPhone iOS app developers in India, you will select best developer or team to create an application for you and get going.