iOS 4 Upgrade Guide

| How-To

With iOS 4 only days away, there’s plenty to think about before upgrading to the newest version of Apple’s mobile device operating system. We’ve put together this guide to help you decide when to upgrade, and what you need to do to be prepared when the time comes.

Should I Upgrade?
Even if you don’t upgrade to iOS 4 right away, you’ll still want to consider making the move soon — assuming you have a compatible device. Currently, iOS 4 is compatible with the iPhone 3G, iPhone 3GS, and iPod touch. First generation iPhone owners are out of luck, and iPhone 3G users can’t take advantage of all of the features in iOS 4. An iPad-compatible version of iOS 4 will be available this fall.

Apple is departing from its usual policy of charging iPod touch owners for major OS upgrades this time around. Instead, iOS 4 is a free upgrade for both iPhone and iPod touch owners.

Here’s some of what you can expect to see once you upgrade to iOS 4:

  • Multitasking support for third-party apps
  • Fast app switching
  • Folders for grouping apps
  • Bluetooth keyboard support
  • Unified inbox in Mail
  • App-level control over Location Services
  • Home screen wallpapers
  • App notifications that don’t require server connections
  • iBooks support

Despite all the new features iOS 4 offers, along with the extensive beta testing it has undergone, it’s probably not a bad idea to wait at least a day or two for all the edge-case problem reports to come in before upgrading. Of course, we’ll be upgrading as soon as Apple’s servers start dishing out the update so we can begin looking for issues that may have slipped through the beta testing process.

Update Your Apps First
Before upgrading to iOS 4, make sure you have already updated to iTunes 9.2 on your Mac or PC. Mac users can go to Apple menu > Software Update, and Windows users can choose Help > Software Update to make sure the most recent version of iTunes is installed.

Next, pay a visit the App Store in both iTunes and on your iPhone and make sure you have the latest versions of all your apps. Most iPhone and iPod touch apps will run just fine in iOS 4, but developers have been hard at work adding support for the new features the OS update includes.

Check for app updates before installing iOS 4

If you aren’t sure how to update apps on your iPhone or iPod touch, check out our Quick Tip to help you through the process.

Check for iOS Compatibility Issues
We suggest making a point of checking developers’ Web sites for any mission-critical apps you run to make sure they aren’t warning about show stopping compatibility issues. If you find any issues with apps you simply can’t live without, we recommend delaying your iOS 4 upgrade until the developers release compatibility updates.

Backup, then Backup Again
Upgrading to iOS 4, or any iPhone OS for that matter, will wipe out your phone and then restore its apps and data. Just like the data on your computer, the information on your iPhone or iPod touch could be forever lost if it isn’t backed up. iTunes backs up your handheld’s data every time you sync with your Mac or PC, so you should already have a copy of all your important information safely tucked away.

You can make doubly sure your iPhone data is protected by backing up your backup. If you already have a strong backup process in place, odds are your iPhone and iPod touch backups are included. If not, or if you aren’t sure if your handheld data is included in your computer backup, check out our Quick Tip on backing up your iPhone’s data.

Save Your Settings and Notes
While the upgrade to iOS 4 shouldn’t wipe out any of your settings, it’s still a good idea to go into the Settings app and note anything you might not otherwise remember if things go south. An easy way to make sure you have an accurate record of all your settings is to use the screen capture feature to take snapshot pictures of your iPhone and iPod touch settings. We have a Quick Tip that details how to take iPhone screenshots and what to do once you have those pictures.

We also recommend emailing yourself any notes you can’t afford to lose. To email a note to yourself, tap the Notes app icon, select the note you want to email, and then tap the envelope icon at the bottom of the screen.

Copy Your Data Back
After you upgrade to iOS 4 there’s a chance that some of the applications, music, or videos that you expect to see won’t be there if, at some point, you told iTunes to stop syncing and disabled its warnings. Re-enabling warnings in iTunes will gives you the opportunity to transfer apps and media back from your iPhone that otherwise might get missed.

Resetting warnings in iTunes
To re-enable warnings for your iPhone or iPod touch, connect your handheld to your computer, Ctrl-click or Right-click on your device in the Library list, and then choose Reset Warnings from the pop-up menu. We have a Quick Tip that details the process, too. Once you’ve reset the warning, perform another sync, and iTunes will obediently display any warning dialogs that were previously hidden.

Resetting device warnings in iTunes

Upgrading to iOS 4, Finally
Now that you’ve covered as many of your bases as is reasonable (and perhaps unreasonable but, hey, we’re playing it safe!), go ahead and tell iTunes to install the iOS 4 on your iPhone or iPod touch. Remember, the iOS 4 update for the iPad won’t be available until later this year.

iTunes checks for OS updates on a regular basis, but there’s a good chance that schedule doesn’t coincide with the iOS 4 release. You’ll probably have to force iTunes to check Apple’s servers for the update, which isn’t a complicated process. If you aren’t sure how to manually check for iOS updates in iTunes, we have a Quick Tip that can help you out.

The OS download and update process will take some time. Afterwards your phone will need to be reactivated online, so make sure you’ve got plenty of bandwidth (and battery power, if on a laptop) to get the job done.

Once the update is complete, go through your iPhone and make sure your settings are correct. The two places we suggest checking right away are Mail accounts and Calendars because those are areas where users have had issues with prior iPhone operating system upgrades.

To check your Mail and Calendar settings, go into Settings > Mail, Contacts, Calendars and confirm that the Accounts section contains exactly what you expect. Next, scroll down to the bottom of that preference list and confirm that Default Calendar is also set properly.

Post-Upgrade Advice
Once you’ve upgraded your iPhone will, in theory, be fully functional, and all of the data that was there before the upgrade will still be in place. In fact, you’ll likely even find that all the web pages you had open in Mobile Safari are still there.

Because the upgrade completely replaces the firmware on your iPhone, the first post-upgrade Sync will trigger a backup that will take a long time. Depending on how much data is stored on your iPhone or iPod touch, the backup process could take 15 minutes or longer.

Since you’re already in down time-mode because of the upgrade process, this is a good time to go ahead and let that first backup happen incase something goes wrong later. Simply plug your iPhone back into your computer, let iTunes do its thing, and then you’re off and running.

Dive In and Let Us Know What You Think
After you finish the upgrade process it’s time to start playing with the new features in iOS 4, then come back and tell us, and the rest of your fellow TMO Observers, about it all in the article comments.

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Anybody know what the speed performance is like when using the new OS on a 3G iPhone? Much slower?

Jeff Gamet

I’ll be installing iOS 4 on an iPhone 3G as soon as I can get my hands on the download on Monday. I’ll be sure to report back with my findings.


Yes please! I’ve been wondering if it’s worth it for 3G users since most of the new features are not supported by the 3G hardware. If the OS is much slower, then upgrading seems to have few benefits…


Very nicely done, helpful summary, Jeff.  Many thanks!

  - Hill


What about the whole mini SIM thing with the new iPhone 4.  In the past, I could pull my SIM outta my 3G and into a 3GS with no problem.  How will we handle that exchange now?


I have a 3G as well (for now), and I will be reporting on the speed of iOS 4.  As an aside, iPhone OS 3.0 was noticeably slower on my 3G at first.  The speed improved quite a bit with 3.1.

Jeff Gamet

YodaMac -

You can’t use the microSIM from an iPhone 4 in a 3GS because of the different form factor of the cards. I’m curious to see how long it takes someone to build an adapter that lets the 3GS use a microSIM.


I heard some tech bloggers in Japan talking about cutting the cards to make them fit. Not sure if this is reasonable or not ... (That is, making the old cards fit into the new iPhone).


well, very infomative, Thanks!
I think guys might also interested in read this article “iOS4: Everything You Need to Know” located in ifunia iphone column, to get ‘everything you need to know about new features for iPhone users and new tricks for iPhone developers’.


I guess the unified inbox will be a useful benefit for 3G owners…

James R Grinter

Well, the GM (as released to developers) version of 4.0 is a bit slower on a 3G. (But, to be clear, I always had random halts and pauses with 3.1.3 on my handset too.)

With 4.0 you do get the benefit of threaded-email, Notes synchronised with IMAP server, more flexible Calendar display (selectable and deselectable individually), and actual spell-checking as well as typing-error correction.

I definitely agree with the point about checking compatibility issues. For example, there’s a particular problem that affects apps accessing OpenStreet Maps through a commonly used library - I’ve seen it show up in a number of tourist-guide type applications with embedded city maps - it’s easily fixed but you’ll have to wait for the developer to put out an update.

(On the MicroSIM issue, at least one of the operators here in the UK is planning on supplying its MicroSIMs with plastic adapters to enable their use in MiniSIM form-factor phones. A number of third parties are already offering them, too.)


I’ve been running 4.0 on a 3G for a few months now and I would estimate that it runs at about the same speed. You might notice that the home screen appears faster after pressing the home button, which is nice. I have also been using the 3G with multitasking enabled, and it hasn’t seemed to slow down the phone one bit. So I would HIGHLY recommend using the redsn0w tool to quickly and easily enable multitasking on 4.0 with your 3G. However, enabling the Home Screen Wallpaper on the 3G seems to slow it down significantly for some reason, so I would recommend leaving this disabled.


So compyterbandgeek, you recommend doing the upgrade then?

XSemper Idem5

Seems I’m out of luck having the 1st gen iPod touch. I will have to wait until I get the 3rd gen to try out iOS 4


Yea I don’t see a single reason not to. And the price can’t be beat wink. And I love the spellchecking, which I just had to use.


Not in this lifetime…........the last time I “messed” with my IPhone set up, it cost me $60 to get technical help and after 4 hours, I still didn’t have the IPhone back to normal.  I have “fixed” my contact list on the IPhone, eliminating everything I did’t need that downloaded from the computer. I use very few of the apps that I have and I am perfectly happy with the status quo. Why mess up a good thing that is working perfectly for me. I don’t even understand what the upgrades will buy.


Hello—Does anyone know if the threaded emails and combined inbox are compulsory in version 4?  I don’t want either of them.

Actually, there doesn’t seem to be much benefit in it for 3G owners.  Am I right?



Hello?Does anyone know if the threaded emails and combined inbox are compulsory in version 4?? I don?t want either of them.

Actually, there doesn?t seem to be much benefit in it for 3G owners.? Am I right?

No, neither feature is compulsory. There are plenty of reasons to upgrade. Almost every Apple app runs faster in my experience, the new Safari renders HTML5 better, it’s EXTREMELY easy to enable multitasking (which works perfectly) with the redsn0w tool, and pretty soon a lot of apps will start REQUIRING os4 because iAds are only supported in os4 and a lot of devs will want to jump on board with that.

Also on my 3G iOS4 seems to handle joining WiFi networks better.


@ computerbandgeek

Thanks for the info.

You state that it?s EXTREMELY easy to enable multitasking (which works perfectly) with the redsn0w tool”.  Does this mean that multi tasking is available on iPhone 3G (i.e. the second generation iPhone).  All the sites I have looked at say that it isn’t. 



Multitasking is not supported by Apple. They claim it is because of hardware issues, but the crux of the issue is that they want you to upgrade by artificially limiting the phone that you have. Granted, multitasking doesn’t work quite as quickly as it does on a 3GS, but neither does anything else wink.

So yes, using redsn0w to enable multitasking is a bit of a “hack”, but all it really does is chance one line in one file on the iPhone (changes the line that says “Multitasking: False” to “Multitasking: True”) and the actual multitasking is still done by iOS.


@ computerbandgeek

Does redsn0w involve hacking one’s iPhone?



If you consider clicking a few buttons and never touching a command line hacking, then yes wink


So I just upgraded my 3GS. Is there, like, a guide to using the new features? There’s a promo page listing them all at, but absolutely no actual instructions that I can find. *How* do I set up folders, etc?


So I just upgraded my 3GS. Is there, like, a guide to using the new features? There?s a promo page listing them all at, but absolutely no actual instructions that I can find. *How* do I set up folders, etc?

I looked at the iPhone User Guide online and it doesn’t yet reflect the new 4.0 features. I remember seeing video guides on Apple’s website touting some of the new features but I can’t seem to find it anymore. So I guess your best bet is to ask questions on forums wink.

To create a new folder, simply drop one icon onto another.

Chris Reyes

how would i go about that? does redsnow have a tool that will do only that (multitasking) or do i need to jailbreak it?


Give us a slew of new features, but don’t bother telling us how to use them! Nice one; slow claps etc.

(@computerbandgeek - thanks)


No, the only way to modify files on the iPhone filesystem requires jailbreaking. However if you use redsn0w and _only_ use it to enable multitasking, you won’t even know that the device is jailbroken (except the fact that multitasking will be enabled). All you have to do is head over to:

Download the, run it, and follow the onscreen instructions. When you get to the screen with a bunch of checkboxes to select, only check “Enable Multitasking” and uncheck everything else. Feel free to ask if you have any questions!

Chris Reyes

thank you so much! i just installed iOS 4 from itunes today, does redsn0w support this release already? and will this reinstall any files on my phone or will it just modify them so everything stays the same? (the quick and easy way)


It does support this release, even though it says a bunch of stuff about “4.0 betas” on the webpage. It will only modify your current install, unlike the old PwnageTool method that required you to do a restore.

The only thing I forgot to mention earlier (which I really should have, sorry!) is that every single firmware update from Apple will disable Multitasking again, and you will have to visit for an updated version of the tool each time you update the iPhone.

Chris Reyes

thanks for the help.  i kinda figured it might, but will i be able to update to the next version from itunes if i choose to?


Yes, whenever you jailbreak you will ALWAYS be able to update/restore from iTunes, but it will ALWAYS remove the jailbreak every time that you update/restore.

Chris Reyes

okay thats great.  just now my computer wont load the link for it >.<


I’m having the same problem. The poor hacker’s server is getting swamped by the jillions of people that upgraded to iOS 4 today and lost their jailbreak wink

Chris Reyes

ahhh.  i got it.  is redsn0w-mac_0.9.2 the file im looking for (running a mac)? cause it said x86 next to the dl link


Yea that’s the one. x86 just means it’s for Intel macs.

Chris Reyes

okay.  i dont mean to keep bothering, but where would the IPSW file be


Don’t worry, I had a feeling someone would ask that wink

You can find all the IPSW’s that iTunes has downloaded in:
~username/Library/iTunes/iPhone Software Updates/

For an iPhone 3G the file will be called something like iPhone1,2_4.0_8A293_Restore.ipsw

Good luck!

Chris Reyes

1/4 down the page


1/4 down the page

This is an old, outdated method. The latest redsn0w does all of this automatically with one checkbox, without having to deal with Cydia and modifying IPSW files over SFTP etc, etc.

Chris Reyes

i have that file and get, “unable to recognize specified IPSW”


Are you sure you’re picking the right IPSW? If you are, then try downloading and pointing redsn0w to that instead.


Seamless Upgrade….

Started about an hour ago on a 3GS with full 12 screens of apps. Already reorganized everything into folders, and backed them up.

Two things I wasn’t aware of: oops, not so fast. Some trickiness in how the newly created folders are syncing. Seems like they aren’t sticking perfectly through a sync. Getting better tho…

Anyway, two things: On the App screen in iTunes is a new window listing apps that can do file transfers, and a window where those docs will show up… very cool.

Second is the limit of apps per folder, which is 12… so for us app junkies there’ll need to be multiple folders at times.

Smooth otherwise!!


Follow up… here seem to be a number of things that upgrade, like photos for some reason on subsequent sync’s, so maybe that accounted for kind of scrambling my apps everywhere.

Anyway, I now have 12 screens of apps nicely organized in three screens… the home screen, which I keep static, a second page entirely of folders, and the third screen for secondarily used apps, with a catch all folder. All syncs taking much less time now, and the phone seems to work great. I think the default is apps keep running unless you quit them, so I’m thinking for battery usage concerns, making sure to quit everything unnecessary.

Lastly, today I got an error trying to do pre-uprade sync’s. The error indicated a duplicate filename. I sent in a tech support request (one great thing about AppleCare) and got a call in 30 SECONDS. The expert helped me find a file in the iTunes library folder that caused the problem. All told it was a ten minute experience. No other computer manufacturer can touch this service. Apple should tout it more. I know I will…


I just installed this on my 3G iPhone. INBOX is much better. Things seem a little smoother. Camera works a little quicker. I would say that overall there is no negative side to upgrading. No loss of performance ...


Ok, here is my preliminary report on iOS 4 on my 3G. 

1.  Everything seems to be faster!  Apps load quickly, scrolling is smooth, and I could find no apparent typing latency.

2.  I’m going to LOVE the spell check.

3.  Safari does indeed seem to load faster.

However . . .

Two of my 3rd party apps do not work.  Qik Video simply crashes upon startup, and (more importantly for me) iStrobeSoft loads but won’t function.  I hope there is an update soon, because I use iStrobeSoft a lot.


@ anovelli

It would be nice to get something even approaching that service level in South Africa!



Ok, update on the apps that didn’t work with iOS 4 on my GS.

1.  Checked on the iStrobeSoft site and they are aware of the incompatibility.  An update is coming soon, so they say.

2.  Apparently Qik released a different version of their video app.  Not an update.  I had to buy it, and actually had both versions on my iPhone at the same time.  Anyway, the new app works fine.

Oddly, the slowest app on my iPhone 3G with iOS 4 is . . . Settings.


Hi there ... very good article - more helpful than what’s on the Apple website.

The iOS4 update does take a while - so be prepared for a couple of hours worth of downtime, possibly more.
Speed on my IP3G is ok - no noticeable degradation yet.
Some apps are working quicker.

What has baffled me are these 2 issues:
1. Maps does not display the maps, only pinpoint locators. It has a grey background saying “no images” in tile format.
2. Even after restoring my 4-digit lock on the phone, I can’t get “Find my iPhone” to work from mobileme.

Any ideas, anyone ?


Hello everybody having troubles with iOS 4 Software Updating on your iPhone 3G.
I just phoned apple?s technical support. Here is their answer: your product is not covered for hardware repairs and service based on the estimated expiration date, but you can purchase telephone technical support from an Apple expert for $29.
So, if you want to update Software ? pay them money and they will help you to solve YOUR (!!!) problems!


One app that seems quite slow on the 3G with iOS4 is the new iBooks. I downloaded the free ‘Winne the Poo’ book but wow… it’s pretty slow. Useable, but just barely…

James R Grinter

They claim it is because of hardware issues, but the crux of the issue is that they want you to upgrade by artificially limiting the phone that you have. Granted, multitasking doesn?t work quite as quickly as it does on a 3GS, but neither does anything else

I’m not sure I’d agree with it being just because of trying to get you to upgrade.

It really does slow down the 3G - just try bringing up Maps after you’ve run a few other things, and it can completely hang or fail to respond once the last viewed area has loaded in. It does degrade the experience markedly, I was unable to answer an incoming call more than once, due to a complete lack of ‘touch’ response (far worse than ever under vanilla 3.1.*), and that’s pretty important for a phone.

Chris Reyes

I don’t agree with. I’ve put multitasking on my iPhone 3G and it runs just fine. I only used the legit version of the new os for a couple hours, but in that time I had your problem with not being able to answer a call because of no touch response. So I think that’s just the os. And my phone runs just fine. You can’t leave every app on your phone running at the same time, the 3GS and new iPhone can, but the 3G isn’t fast enough. If you open a few heavy apps and leave them running, then open more yes your phone may hang. You need to close the apps your not using. Multitasking isn’t having a bung of unnessesary apps open at the same time, it’s running more than one app at once when you need to. You can do that, you just can’t have maps games the app store safari and more running when they’re not needed. Just quit your apps it’ll run fine

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