剛剛在reddit上看到的，附上原文網址:
https://support.apple.com/en-us/HT201954
Title: Unauthorized modification of iOS can cause security vulnerabilities,
instability, shortened battery life, and other issues
This article is about adverse issues experienced by customers who have made
unauthorized modifications to iOS (this hacking process is often called
"jailbreaking").
iOS is designed to be reliable and secure from the moment you turn on your
device. Built-in security features protect against malware and viruses and
help to secure access to personal information and corporate data.
Unauthorized modifications to iOS (also known as "jailbreaking") bypass
security features and can cause numerous issues to the hacked iPhone, iPad,
or iPod touch, including:
Security vulnerabilities: Jailbreaking your device eliminates security layers
designed to protect your personal information and your iOS device. With this
security removed from your iOS device, hackers may steal your personal
information, damage your device, attack your network, or introduce malware,
spyware, or viruses.
Instability: Frequent and unexpected crashes of the device, crashes, and
freezes of built-in apps and third-party apps, and loss of data.
Shortened battery life: The hacked software has caused an accelerated battery
drain that shortens the operation of an iPhone, iPad, or iPod touch on a
single battery charge.
Unreliable voice and data: Dropped calls, slow, or unreliable data
connections, and delayed or inaccurate location data.
Disruption of services: Services such as iCloud, iMessage, FaceTime, Apple
Pay, Visual Voicemail, Weather, and Stocks, have been disrupted or no longer
work on the device. Additionally, third-party apps that use the Apple Push
Notification Service have had difficulty receiving notifications or received
notifications that were intended for a different hacked device. Other
push-based services such as iCloud and Exchange have experienced problems
synchronizing data with their respective servers.
Inability to apply future software updates: Some unauthorized modifications
have caused damage to iOS that is not repairable. This can result in the
hacked iPhone, iPad, or iPod touch becoming permanently inoperable when a
future Apple-supplied iOS update is installed.
Apple strongly cautions against installing any software that hacks iOS. It is
also important to note that unauthorized modification of iOS is a violation
of the iOS end-user software license agreement and because of this, Apple may
deny service for an iPhone, iPad, or iPod touch that has installed any
unauthorized software.
簡單來說，就是指任何對iOS裝置進行未經授權的修改行為(也就是越獄)，
會造成裝置的安全性下降，導致惡意程式可能藉此入侵裝置。
並且有些軟體的使用可能會使iOS裝置變得更加耗電，
還有可能導致一些正常的App的運作出現錯誤或是閃退等現象
進行嚴重的修改的話還可能會造成iOS出現無法修復的錯誤，
並在進行系統更新時使裝置無法使用。(淦哪個白癡在越獄後還會升級啦)
最後，說是越獄違反了iOS的使用者同意條款，Apple有權拒絕服務
任何有安裝未經授權軟體的裝置。
雖然很想吐槽蘋果竟然敢說自己系統很穩定，不知道是哪來的自信
但他說的其實也沒錯啦。越獄本來就要自己承擔各種風險。
如果今天裝置真的是因為越獄而導致損壞，他們也沒必要進行負責。
就像Android現在很多廠商也是只要root就得先解鎖Bootloader，
解鎖Bootloader的話裝置就會破保。
只能說我還是會繼續越獄下去，但是要提醒大家要小心，
不要在越獄之後就在Cydia裝盜版軟體，或是跑去亂超頻什麼的。
因為已經取得裝置的最高權限了，做什麼都要謹慎。