iOS or iPhone OS is a mobile operating system developed and distributed by Apple Inc.
Originally released in 2007 for the iPhone and 'iPod Touch'; it has been extended to support other Apple devices such as the iPad and Apple TV.
Smart phone by Apple - iPhone, has written new records of success in the mobile industry.
iPhones are nothing less than pocket computers with utility rich features like amazing integration, easy synchronization, live YouTube videos, zoom features, top class web browsing, rotate screen, ibooks, face time calling, retina display, slide to unlock, etc.
These features make iPhone, one of the best smart phones available in the market.
A lot of new features have been added in the latest version of the iPhone, which is the iPhone 5.
With iPhone 5, the demand for these phones has increased manifolds.
Not only the phone, demand for iPhone 5 applications, has also shown tremendous increment.
iPhone app development is heading straight towards achieving new heights in the mobile application development industry.
Every big and small IT company is getting into iPhone application development to exploit the popularity and success of iPhone.
Therefore, mobile application development companies are on hiring spree for iPhone app programmers and developers.
This has paved new path and created tremendous opportunities for these professionals as they are facing sharp increase in their demand.
iPhone applications should be very patiently developed as they need to get through the tough test of Apple Inc.
before getting in the app store for public.
That is why, iPhone application developers have to be very patient when they are working on this device's applications.
This patience and expertise could be considered as pre-requisite for being an iPhone programmer or iPhone application developer.
As discussed above, companies want to hire expert iPhone app developer to create a pool of talented and experienced professionals, so that they could capture the largest share of this growing market.
However, every company should select their programmers and developers with utmost care.
Few facts to consider while hiring iPhone app developers are as follows:

• Find out what kind of apps the developer has created, till date.
  
• Ensure to ask the developer to present his or her portfolio.
  
• Check the utility of the apps on iPhone devices.
  
• Identify the level of creativity.
  
• Check his or her ability to create or build usable iPhone apps.
  
• Relevant experience is also necessary.
  
• Reference check of the clients should be conducted.
  
• Know their technical expertise and knowledge about the iPhone SDK and other creative tools.
  
• Find someone with good communication skills.
  
• Verify whether the developer is ready to sign Non-Disclosure Agreement or not.
  
• The developer should also have expertise in:
1. Internet application
2. Games development
3. Utility applications
4. Fun applications
5. Language conversion
6. Multimedia application
7. Apps for Medical
8. Apps for Business
9. Music applications
10. Entertainment application
11. Maps and navigation application
12. Travel & Lifestyle application
13. Book publishing application
14. Augmented Reality App
15. Etc.
    

The iPhone developer should also be cautious while selecting a company.
He or she should consider the following points before indulging with any IT company:

• Technical expertise of the company should be verified by enquiring about the available technology and infrastructure at the office.
  
• Experience of the company in terms of having clients and developed apps should also be considered.
  
• Quick turnaround time is another criterion to be considered as this will show what technical capability the company already possesses.
  
• Clarity in terms and condition and especially in NDA should be there.
  
• The company should offer you a reasonable amount of remuneration as iPhone app development industry is at boom and due to high demand; the developer will be expected to work very hard.