iOS is the operating system implemented by Apple on all its mobile devices such as iPhone, iPad, and iPod. Ever since its first version was released in 2007 together with the first iPhone, it has gradually evolved incorporating new functions and features that have helped it remain for some time ahead of its rival, Android.
Its ninth version, Apple iOS 9, was published in September of 2015 and it's the last to be compatible with the iPhone 4s (iOS 10 cannot be installed on this mobile device).
Main features and updates included in iOS 9
The main features that any user will appreciate in this version of Apple's mobile operating system can be summarized in the following functions:
- Notes: the notes app now allows us to include photos, hyperlinks, videos, drawings... as it's synced to iCloud, we can add elements from Safari or Maps from other devices.
- Maps: they're no longer that bad and now include public transport lines in certain cities.
- CarPlay: improvements to the connection and performance.
- Multitasking: the screen can be split 75/25 or 50/50 for applications on certain iPad models and video playback can be minimized.
- News: there's a new news app for certain countries.
- Siri: the assistant has been provided with a new interface.
- Battery: the energy saving mode can increase the length of the battery up to 3 hours.
- Keyboard: updated with a top bar for iPad that allows us to format our texts.
- Security: improved protection against remote attacks and introduction of a customizable 6-digit PIN number.
What devices are compatible with iOS 9?
As we said before, this is the last iOS compatible with the iPhone 4s. Apart from this device, it can also be run on all iPhone 5, all iPhone 6, iPhone SE, fifth and sixth generation iPod touch, third and fourth generation iPad, iPad Air 1 and 2, iPad mini 1, 2, 3, and 4, and iPad Pro.
The latest update to this operating system was in August of 2016, moving on to version 9.3.5., the last one before the presentation of iOS 10 and the new iPhone 7.