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I'm working on an iphone project for OS3.1.3. I updated my iPhone to iOS4 and now I can't test my project on my iPhone anymore. I tried downgrading but get "device not eligible"

What should I do now?

If I download latest XCode SDK4 will I be able to recreate my app so that it runs both on OS3 and OS4 ? It has no specific os4 features.. it should just run on both and want to test it on real iphone with os4..

Greets

Thomas Joos
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  • Not a programming-related question. Seriously, do you really think this has anything to do with programming? – Emil Jun 22 '10 at 12:16
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    iPhone programming starts with setting up an XCode project and I did not know if I would be able to test projects for OS3 compiled with SDK4.. so in my honest opinion, besides the fact you might find it a silly question, I think it has something to do with iPhone programming yes. Thanks Sam for your quick reply! – Thomas Joos Jun 22 '10 at 12:34

4 Answers4

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First of all, downgrading your phone won't work. at least not with the "official" approach. I think once there is a Jailbreak for iOS4, downgrading your phone should be possible again.

Secondly, Creating an iOS app with XCode SDK4 that runs on your 3.x devices is no problem at all:

Just set the "iPhone OS Deployment Target" Value (Target -> Info -> Build) to "iPhone OS 3.0"

samsam
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  • All right, the app has no specific iOS4 features, so if I build and test on my 3gs with iOS4 it will perform the same as on a 3gs with OS3? I don't have an OS3 iPhone atm because the downgrading failed :) Greets – Thomas Joos Jun 22 '10 at 12:03
  • yep it will. XCode might give you some compilerwarnings of code that is deprecated under 4.0 (for example the SetStatusBarHidden method), there you could check within your sourcecode wether the current device responds to the new methods, you can do that by calling [self respondsToSelector...) – samsam Jun 22 '10 at 13:52
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    -1: You can never downgrade an iPhone 3GS unless you have your SHSH blobs saved: see http://saurik.com/id/12 – Grant Paul Jun 23 '10 at 22:23
  • Pity everything always comes down to jailbreaking with Apple... at least its legal now. Imagine how much people would hate it if jailbreaking wasn't possible.. – WalterJ89 Aug 13 '10 at 15:11
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You can build with SDK4 and still target older devices running iOS 3.2 or earlier. How to do this is covered in detail in this other question here.

You can downgrade your phone OS, that's covered in this question over here.

But really the best approach is to update Xcode, compile with SDK4 and support earlier iOS versions as well.

Community
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progrmr
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I'm in the same situation.

What is the best ? 1 Upgrade to SDK4 and still target on IOS 3.xx . Will iPhone ios 3.1.3 users be able to download apps built with SDK4 . I don't think so. 2 Downgrade ios4 to ios3 and still work with SDK3.

PS : Someone suggested to get the lastest SDK

Raymond Chenon
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You can downgrade iPhones, iPod touches and iPads.

Instructions are here. If for instance you're downgrading a second generation iPod Touch from iOS4 to iOS3.1.3 you'll need the iPod2,1_3.1.3_7E18_Restore.ipsw firmware. A Google search will bring these things up.

Some downgrading references ask you to modify a "hosts" file. I don't think this is necessary, I downgraded from iOS4.2 to iOS3.0 (and to iOS2.0 for fun) without having to do this.

Good luck.

Ken
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