Only certain devices were able to use multitasking — iPhone 4, iPhone 3GS, and iPod Touch 3rd generation.

1. • June 21, 2010 – Multitasking for iOS was released along with the V. 4.0
 Only certain devices were able to use multitasking — iPhone 4, iPhone
3GS, and iPod Touch 3rd generation. The iPad did not get multitasking
until the release of iOS 4.2.1 in November 2010.
• the first major release to drop support for some devices, as well as the first
update that iPod Touch users did not have to pay for.
• iOS 4.0 was announced to have over 1500 new APIs for developers,
supporting the highly anticipated multitasking feature.

2. – Apple Inc. presented the new
iPhone 4 in San Francisco, California. Apple also
rebranded iPhone OS as “iOS”.
– iOS 4 software is available as a free
software update via iTunes.
– available in the US, UK, France,
Germany and Japan, starting in the US at just $199
for qualified buyers with a 2 year contract.

3. run multiple applications at the same time.

4. • change the background picture
on your devices home screen.
• the default background
in iOS 4 is water drops on gray.

5. • Words the OS thinks you've misspelled
will be underlined in red (familiar to any
Microsoft Office or Mac OS X user).
Tapping on them will give you a popup
containing a recommended replacement.
Tapping the popup replaces the
misspelled word with the (hopefully)
correctly spelled one.

6. •Cut, copy, and paste also gets
an iPad-debuting feature with
"replace“ the popup options.

7. •use a wireless keyboard
on the iPhone (you
can use a wireless
bluetooth keyboard with
the iPad right now)

8. •organize apps into folders.
•A folder is simply a grouped
icon that holds up to 12
other icons inside it.

9. • gets a character counter so you'll
know when you're getting close
to, or going past, the SMS limit.
• iOS 4 will now put an exclamation
badge on the Messages app as a
way to inform you when an SMS
text or MMS multimedia message
fails to send.

10. •you can now show all or hide
all calendars or individually
check/uncheck just the
calendars you want to see.
•Birthday calendars have also
been added to the option.

11. •view photos based on where
they were taken & who’s in
them.
•Landscape mode is also now
supported in album and gallery
views.

12. •New 5x digital zoom. When you
tap the screen, a slider pops up
allowing you to swipe to the right
to increase magnification and
swipe left to decrease.
•With iPhone 4, there's an
additional control to swap
between the beefed up 5mp
back-facing camera, and the all
new front-facing VGA camera.

13. •You can now watch YouTube
videos in portrait mode if you
really want to. They'll still
default in landscape, so you
may have to rock the
accelerometer back and forth
to get them to switch.

14. •A minor tweak, but the current
location/current direction
button changes from the
previous crosshairs to a north-
east pointer to match the new
location services icon used in
the title bar.

15. • When you first enter notes it looks
unchanged from previous versions of
the iPhone OS. However, there is now
an Accounts button at the top left of the
list page and tapping it takes you to a
new screen where you can choose to
view All Notes, just the notes on your
iPhone, or just the notes that are synced
via IMAP to your email account(s).

16. •The biggest addition to the iOS
4 Phone app.
•When connected to Wi-Fi &
making a call to another iPhone
4 user, the Hold button gets
replaced with a FaceTime video
icon.

17. • multiple mail accounts in a single
inbox.
• for heavy ActiveSync users, iOS 4
supports multiple accounts. So, for
example, you can now have your
work Exchange server and home
Google account both set up to push
through ActiveSync (which is what
Google Sync users behind the
scenes) at the same time.

18. •browse, buy, and read
eBooks.
•Not a built-in app. You'll
need to go get it from the
App Store.

19. •send apps as gifts
to others.

20. • Stocks: Similarly, Stocks got landscape and a slew of swipe-able data last
time, so the update love gets skipped this time.
• Weather: Almost comedically at this point, it's still unchanged from
iPhone 1.0. Still no HTC TouchFlo 3D style animations, no landscape mode
with more/different information. Not even a Calendar-style icon update to
show current local weather. Nada.
• Voice Memo: Introduced in iPhone 3.0, it looks pretty much the same in
iOS 4.
• Clock: With nothing but a lap feature added last time, we lose the "but"
and keep the "nothing" for iOS 4.
• Calculator: Upgraded back in 2.0 for landscape scientific mode, all
Calculator gets this time is a slight icon tweak towards the red.

21. 1. Background audio – application continues to run in
the background as long as it is playing audio or video
content.
2. Voice over IP – application is suspended when a phone
call is not in progress.
3. Background location – application is notified of
location changes.
4. Push notifications –provide sound, badges, and alert
popups for everything from IM to game challenges.

22. 5. Local notifications – application schedules
local notifications to be delivered at a
predetermined time.
6. Task completion – application asks the
system for extra time to complete a given task.
7. Fast app switching – application does not
execute any code and may be removed from
memory at any time.

23. • iOS 4.0.1 (and iOS 3.2.1 for the iPad) was released in July of 2010 in
order to address the issue, normalizing the number of "bars"
displayed.
• iOS 4.1 helped Apple cement its mobile gaming lead by introducing
Game Center, which added some limited but sorely needed social
networking to iOS' gaming ecosystem. Apple also added support for
renting TV shows directly on iOS devices as well as support for it's
Ping social network for music, the latter of which was and is little
used. On the camera front, iOS 4.1 added support for HDR
photography to automatically combine two photos with different
exposures as well as full HD video uploads to YouTube.

24. • iOS 4.2.1 brought multitasking and folder support to the iPad, giving iOS
the same version number and features across all of its modern devices (the
iPhone 3G and iPod Touch 2nd Gen offered limited support for iOS 4's
features). Apple also introduced AirPlay for streaming video content
between iOS devices and the Apple TV. It's a feature that doesn't get as
much attention as it ought compared to video and audio stream solutions
on other platforms, it’s miles ahead. Lastly, this update introduced AirPrint
for those who still bother with that sort of thing.
• iOS 4.2.5 came along solely to support the Verizon version of the iPhone.
That purpose actually brought with it an added benefit: full support
for Wi-Fi-based mobile hotspots. Apple followed up with
• iOS 4.3 in March, adding AirPlay support for 3rd party apps, iTunes Home
Sharing support for playing music off your local Wi-Fi network, and support
for Personal Hotspot on GSM devices.