It is indeed an evident factor that Apple's iOS is considered as the most restrictive and closed operating system, which is due to the simple philosophy Apple holds for their operating system. The Cupertino based company does not want any third party applications messing their operating system and ultimately creating trouble to end users.
Apple has more than once revealed the fact that they respect their user's identity and they do not wish users employing iOS operating system to even accidentally share their data with third party or mess their handsets.
Until recently, tech savvy users had an option to get into personal data of users with an option of jailbreaking. Jailbreaking was ultimately designed to unlock user's phone and gain an instant access to their personal data. This was made possible with the help of custom made software that were capable of cracking iPhone security system.
With the latest edition of iOS 9 in market, users are waiting for the right jailbreaking system that can crack the new OS; however, as things stand, it would not be wrong to suggest that another jailbreaking tool to crack the newer version of iOS 9 may not see light for few years now.
Apple has tightened its security strategy without any loophole to jailbreak into the new iOS version. Although certain users of iPhone community prefer to jailbreak their devices and install applications, this could not be considered as a right practice. Yet another group of people hold the argument that iPhone could offer their own solution to such issues instead of users relying on jailbreak system.