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Is it possible to use an iOS browser for Mac such as Phone Disk to apply a jailbreak tweak to a non-jailbroken iOS device?

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What sort of tweaks? – Vlad Mar 21 '12 at 22:24
@Vlad This is mostly hypothetical, but in general, probably system tweaks (specifically to the lock screen and Springboard). – timothymh Mar 21 '12 at 22:26
I have not tried Phone Disk but my guess is there are areas (such as /System) where a non-jailbroken iPhone won't allow you to write (due to missing privileges). You can mess around with apps' data though, since that will not require superuser access. – Vlad Mar 21 '12 at 22:37
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The carrier name (or iPod or iPad text in the upper left corner) can be changed by editing backup files. – Max Ried Oct 31 '12 at 6:41

4 Answers

up vote 4 down vote accepted

No, you cannot, for a number of reasons:

  • Most (when I say most, I mean all but a few) Jailbreak tweaks modify files outside of your user profile. This is a separate partition and cannot be accessed unless you have root access (you have to be Apple or you have to be Jailbroken).
  • Jailbreaking, from a low-level point-of-view, simply makes it so you can run unsigned code on iOS, which allows you to break out of the sandbox environment in /private/var/mobile/. This allows you to install Cydia, modify system files, and gain root access.
  • If you notice in your iOS browser on your computer, you can only access things in /private/var/mobile/ (or it might even call it /, because that's what a sandbox does - it's chroot). Even if the file browser is cool enough to read on your true /, it's not going to be able to write.

With that being said, you're going to have to Jailbreak in order to install Jailbreak tweaks.

Note: I haven't used Phone Disk, but iFunBox is pretty much the same thing.

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A shame this was accepted as it is full of misinformation. 1) You don't need to install a deb packager (dpkg-deb or apt-get) on your device (jailbroken or no). You can just as easily unpack the deb file on your computer, installing the files manually. 2) without jailbreaking, you cannot access the contents of /private/var, just /private/var/mobile, which is where your user (or mobile account) is sandboxed to. 3) Tweaks don't necessarily install to root (/) or (/System) and from a security standpoint, they are one in the same. Anything outside /private/var/mobile requires root access. – cksum Mar 22 '12 at 3:21
I realized soon after I answered this that you can't access /var when you're not JailBroken, and the User profile being at /private/var/mobile, but I haven't had the chance to come fix that until now. As for the depackager, I hadn't thought about unpacking them on a computer and installing them manually. It does make sense, though. As for tweaks installing to / and /System, I just named the two most common places that tweaks install to. Also, correct me if I'm wrong, but isn't /private/var just a symbolic link to /var? – Andrew Larsson Mar 22 '12 at 4:35
I edited my answer to include what you said and to correct /var to /var/mobile/. – Andrew Larsson Mar 22 '12 at 4:42
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All tweaks are installed in /Library on the System partition. The main reason you cannot use tweaks on an unjailbroken device is not because of filesystem access - it is because the iOS kernel has strict codesigning restrictions, which MobileSubstrate, the tweak loader, cannot operate under. – conradev Mar 23 '12 at 2:32
I've seen plenty of tweaks that merely modify .plist files in /private/var/mobile/Library/Preferences. Your other reason is already listed, but you also need to have root permissions. – Andrew Larsson Mar 23 '12 at 2:38
up vote 5 down vote

It depends.

There are some hacks, such as a hidden panorama mode, which reportedly work without a jailbreak. The App to use on your Mac or PC to make the necessary changes to tweak your iPhone is called iBackupBot. I'll bet if you dig around those files, you may find more cool things.

Remember, a jailbreak consists of a firmware image which has been modified, presumably at the binary level. (Odds are that jail breakers don't have access to iOS's actual source code. So, they'd use tools like binary/hex editors.) Hacks that require binary changes can't be used without changing the code that the phone executes. Changing the binary code is the essence of a jailbreak.

However, sometimes, as in the case of the hidden panorama mode mentioned above, apps (or even parts of iOS, more below) will read "settings" or "preferences" from external files. In those cases, simply supplying another value by editing property-list files may cause the app to act differently.

Apps that tap into the Settings app to store their settings write those settings to the phone's persistent storage as property-lists, which are simply a special form of XML.

In the panorama mode example, the Camera app looks inside the relevant property-list file to check for a "flag" or a switch which will turn panorama mode on or off. There just isn't any user interface for turning the mode on or off. (For clarity's sake: The XML to turn panorama on is not in the same place that most settings are.)

Using the tool mentioned in the article, I've noticed that technically, which icons are shown on SpringBoard is also editable. There are tens of property-list files which configure the system, you just need to have access to them and know what values might be useful.

iOS uses a lot of "Property Lists" and XML, and knowing what does what can yield interesting results. Just bear in mind that most of the "useful" hacks are either available via Settings, or only via a binary jailbreak.

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That is pretty cool. Kind of like a way to bypass the need to jailbreak if all the "tweak" involves is a defaults write command to set a hidden preference that the device has code to handle. So the real answer to this question is a resounding - no you can't get new code to run or change existing code, but yes - some plist files can be edited or created within an app's sandbox to enable non-default and hidden behavior of existing apps. – bmike♦ Mar 22 '12 at 15:47
That looks interesting. A program that lets you modify .plist files from an iPhone backup could come in handy. – Andrew Larsson Mar 22 '12 at 16:21
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Besides the panorama mode preference (which I discovered) there is also a preference to enable an autocorrections bar. And, actually, tweaks are dynamic libraries loaded into executables by something called CydiaSubstrate, and they modify the Objective-C runtime. – conradev Mar 23 '12 at 2:37
@conradev - Wow, thanks for the insight! Do you have any websites I can use to as a reference? Also, totally forgot about the autocorrect bar. – Moshe Mar 23 '12 at 2:51
up vote 3 down vote

No. Tweaks and items found outside of the App Store are not given permission to run on iOS. Any program must pass a series of checks before it is allowed to execute. Jailbreaking removes (most of) these checks.

Moreover, they all require various frameworks and libraries also not included in Apple's mobile operating system.

Lastly, you may only copy things to your user account. Tweaks and apps found in Cydia require root access (and that can only come by way of jailbreaking).

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up vote -1 down vote

Some of these old posts contain misinformation. You can install cydia apps/tweaks and maintain a sandbox.

The weblin and ipwnstore are cool stuff. Most of my tweaks still do rely on being out of the sandbox.

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Please expand on this a bit. I can help with grammar if you are not a native speaker - just flag it and let us know. Thanks for pointing out old information by an edit or a new answer. – bmike♦ Oct 31 '12 at 20:18
I took a look at those two stores. They only install apps (or tweaks that modify files in the strictly in the mobile user's partition), so this is technically nothing that hasn't already been said. – Andrew Larsson Nov 6 '12 at 0:06

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