Recently Jay Freeman a.k.a. Saurik, inventor of Cydia and master of all things jailbreak, has been getting some publicity explaining the benefits of jailbreaking iOS devices (iPhones, iPod Touches etc). When asked of any risks associated with jailbreaking, I feel Jay did not give a full and honest answer, so here are what I believe to be the main reasons not to jailbreak your iPhone.

Before I begin, here is Jay’s answer to the question of “What are the downsides of jailbreaking?”

The one thing you have to be careful about is when you come to update your phone, make sure there is a jailbreak available for that firmware before you update it

Hmm. I think he had his sales hat on a bit too tight. I think there are a lot more things to consider. I understand why he wouldn’t want to highlight these points as he is trying to increase user adoption of Cydia/jailbreaking (he makes money from selling apps on Cydia), but these are real issues that people need to be aware of.

Performance

The stock iPhone runs a finely-tuned OS, designed to give the high-level of performance inherent in all Apple products. This consistent and fast experience is something Apple pride themselves on delivering and should be seen as a major reason for purchasing an iPhone.

Every additional tweak, customisation and app installed from Cydia has a very high chance of impacting this level of performance to some degree, by using up additional memory (RAM) and CPU cycles. Usually an individual tweak will be negligible in its impact, but combined it is easy to reduce the overall performance of your phone and in doing so remove one of its biggest strengths.

The only times I have ever had to restore my iPhone was to restore performance that had been degraded by too many Cydia customisations. These days I am very strict about the jailbreak tools I install.

Security

A jailbroken iPhone allows apps to access core OS files and folders that App Store apps cannot. While this allows apps to offer additional functionality, it must be acknowledged that this increases the chance of something going wrong. Best case scenario, an app modifies some files incorrectly and something stops working, which is easily fixed by restoring your phone.

However, malware on jailbroken iPhones has already been discovered. In addition, jailbreaking does not automatically prompt you to change the admin passwords that allow for fundamental changes to take place (impossible on a stock iPhone). A user has to follow a fairly laborious process (for the “average” user) to secure this, and if they don’t then their phone is basically open to hacking, even remotely.

Battery life

It is hard to be specific, but any app that takes up additional CPU cycles will likely use more battery. iPhones are not known for their long battery lives so be warned that the more jailbreak apps that run in the background or foreground will probably shorten the battery life (time between charges). While this is of course true with ordinary applications, many jailbreak apps are more subtle in their operation and so a user not clued up may not realise why their phone is running out of charge quicker than usual. This obviously impacts the above point about overall performance.

Reliability

Jailbreak apps are not subject to the tight controls and auditing that Apple enforce upon any applicant to the official App Store. You can fairly sure that if you download an app from the app store, it is going to work. Therefore not only are jailbreak apps more likely to crash, because their influence can extend to more fundamental areas of your phone they are therefore more likely to crash your entire phone, requiring a restart. In my experience this is not a common occurrence, but the increased possibility is very real nonetheless.

Features

If you rely on a jailbroken iPhone, you will have regular periods where you will miss out on new features released for free by Apple while you wait for the jailbreak community to create a new fix for the current version of the software. This can be days, weeks or months, and there is no guarantee that Apple won’t quickly patch again whatever exploit has currently been used to create the jailbreak.

It is also worth noting that to date I still have not found a clear explanation of how to retain all of your jailbroken apps and tweaks when upgrading.

In summary

Most of the above points are not reasons to not jailbreak your phone, as long as you understand the risks and take the necessary precautions. Most people who do jailbreak I expect are relatively tech-savvy, but if Jay is looking to appeal to wider masses, he could be opening up a can of worms if people start being affected by the above issues having not been fully aware of the implications of jailbreaking.