iOS, a mobile operating system developed by Apple, has had a wide range of bugs and security issues discovered throughout its lifespan, including security exploits discovered in most versions of the operating system related to the practice of jailbreaking (to remove Apple's software restrictions), bypassing the user's lock screen (known as lock screen bypasses), issues relating to battery drain, crash bugs encountered when sending photos or certain Unicode characters via text messages sent through the Messages application, and general bugs and security issues later fixed in newer versions of the operating system.
iOS 4
Alarm clock bugs Users reported bugs in the Alarm functionality of the Clock app in all versions of iOS 4. The first bug noticed was the "DST bug" which was first seen when some countries switched to/from daylight saving time from/to standard time in October or November 2010. It caused recurring alarms to go off an hour too early or too late. Apple promised the bug would be fixed in iOS 4.2, but according to some reports it still existed in iOS 4.3.1.
The second alarm clock bug discovered was the "New Year's Day bug" which showed up on January 1, 2011, and January 1, 2012. It caused non-recurring alarms to never work. However, two days after each New Year's Day, on January 3, 2011, the bug appeared to resolve itself. This bug was seemingly fixed in iOS 4.3.
Location data retention issues At the 2011 O'Reilly Where 2.0 Conference Alasdair Allan, a researcher at University of Exeter, and Peter Warden, of Data Science Toolkit revealed that they had found an unencrypted file on their iPhones titled "consolidated.db" which contained a series of coordinates. At first the researchers thought it must've been a log of image location data. However after plotting the coordinate data onto a map they came to the conclusion that the data was actually a log of every cell tower they had connected to and every location they had visited from the past year. This raised concerns from multiple privacy advocacy groups as this data is usually only obtainable with a court order. The concern then lead to outrage from customers who felt violated by the alleged breach of privacy. This prompted a response from Apple who denied it was tracking users and instead claimed “The location data that researchers are seeing on the iPhone is not the past or present location of the iPhone, but rather the locations of Wi-Fi hotspots and cell towers surrounding the iPhone's location,”
Apple further claimed the purpose of the data was to assist the iPhone in rapidly and accurately calculating location. While they did concede that the device was storing the data too long, Apple also blamed the length of time the data was stored on a bug present in the release of iOS 4 that would be fixed soon. Apple attributed the outrage to a misunderstanding of the technology used in their devices. The bug was fixed in the release of iOS 4.3.3 on May 4, 2011 by reducing the cache to only 7 days worth of data, ceasing iTunes backups for location data, and lastly by deleting the entire cache whenever a user turned off "location services" in their settings.
iOS 5
Battery drain bugs Apple confirmed that several battery life bugs were negatively affecting battery life in iOS 5. Apple attempted to fix these bugs with iOS 5.0.1 and 5.1 but the problem still remained. All of these bugs were fixed in iOS 5.1.1.
Wi-Fi The launch of the iOS 5 update on October 12, 2011 (including iOS 5.0.1 released on November 10, 2011), led many users to report a major bug causing the device to lose Wi-Fi access. This problem was supposedly fixed with the release of iOS 5.1.1.
SIM card Some users of the iPhone 4S and iPad (Wi-Fi + Cellular) reported issues with the SIM card in iOS 5.0, and even though Apple attempted to fix these issues in version 5.0.1 build 9A406 (for iPhone 4S only), they still remained.
Echo bugs Some users of the iPhone 4 and iPhone 4S reported issues with having echo problems during phone call in the initial release of iOS 5, which caused echoes to appear randomly during phone calls made through earbuds. The other party in the call was generally unable to hear the conversation due to this problem. Apple released version 5.1.1 in an attempt to fix the problem.
iOS 6
Maps
Apple admitted that there were several bugs in the mapping app on iOS 6, with cities in the wrong location, some places missing altogether, some places misnamed, and some places of interest in the sea. Problems submitted by users were gradually addressed with daily updates to Maps.
Bluetooth Many users reported a problem with Bluetooth audio streaming to a range of compatible devices. The sound cut out occasionally for no apparent reason. , no solution was provided by Apple.
Location-based reminders Location-based reminders did not work for iPads, even though they were promised to work on cellular-enabled devices. It was later clarified by Apple that only the 4th generation iPad and the iPad Mini 1st generation or later would be able to use this.
Cellular Network In iOS 6.1, users reported problems with cellular connectivity. This was addressed for the iPhone 4S in iOS 6.1.1 which "fixes an issue that could impact cellular performance and reliability for iPhone 4S."
Do Not Disturb Many iPhone users experienced a bug with the Do Not Disturb feature when the calendar changed from 2012 to 2013. The feature would be left on past the scheduled time set by the user, allowing texts, notifications, and alarm settings to be missed. The bug was caused by a difference in formatting in the ISO calendar system versus the Gregorian calendar system. Apple did not offer a software update, saying that the bug would resolve on January 7, 2013.
Microsoft Exchange Another bug caused issues when iOS devices connected to a Microsoft Exchange server to retrieve email, resulting in message "mailbox server resources are consumed, log growth becomes excessive, memory and CPU use may increase significantly, and server performance is affected". Microsoft suggested several workarounds; the bug was fixed with the release of iOS 6.1.2.
Lockscreen bypass code On iPhones, another bug found in iOS 6.1 allowing bypassing the lock screen's passcode to temporarily gain full access to the Phone app, by performing a specific sequence of actions on the phone. This was fixed with the release of iOS 6.1.3.
Audio profile speakerphone iPhone 5 users experienced dropped calls during the release of iOS 6.1.3 when there was an issue with the audio microphone profile. This also caused issues with many voice-over commands, including Siri, to get different results than expected or to fail easily. Apple fixed this bug with the release of iOS 6.1.4, which updated the audio speaker profile so users would get better results.
FaceTime Shortly after Apple released iOS 7, users running iOS 6 were said to have problems using FaceTime. Apple later released a support document stating that this was due to an expired device certificate and that devices that supported iOS 7 should update to it to resolve these issues, and that devices unable to run iOS 7, the fourth-generation iPod Touch and the iPhone 3GS, should upgrade to iOS 6.1.6.
Data security An attacker could collect or modify data in sessions protected by SSL/TLS protocols. This same bug was also reported on iOS 7.0.4 and iOS 7.0.5 for the iPhone 5C and 5S. For the iPhone 3GS and the iPod Touch (4th generation), iOS 6.1.6 was released to fix this issue since iOS 7 is not compatible with these devices. (see iOS 7.x)
iOS 7
Passcode screen bypass bugs A lock screen bypass was discovered in 2013 within hours of the release of iOS 7, caused by the ability to use the control center through the lock screen and tapping on the camera or timer buttons. The latest iPhone models, the iPhone 5S and the iPhone 5C, were not affected. As a workaround, the Control Center could be turned off for the lock screen in the Settings app. This was fixed in iOS 7.0.2.
Motion sickness Users complained about motion sickness-like symptoms when using iOS 7 because of the user interface's animation and parallax effects. In iOS 7.1, a new function in the Settings app named "Reduce Motion" was introduced to reduce the motion of the user interface and disable the parallax effects.
Creation of CardDAV Accounts not working Creating a CardDAV Account had a bug that required manual fixing of the CardDAV-Server-URL.
Battery drain problems Users reported seeing significant drain on their devices' battery after installing the update to iOS 7.1.
Safari ignores local domain Local domain names could no longer be resolved in Safari, breaking short names on the local network.
Home screen crashes Users reported various crashes of the home screen, the core service that renders the home screen icons, Notification Center, Control Center, Siri and the lock screen. This was fixed in iOS 7.1.
Data security Secure transport failed to validate the authenticity of connection. This issue was addressed by restoring missing validation steps. This could allow an attacker with a privileged network position to capture or modify data in sessions protected by SSL/TLS. This issue was addressed by the release of iOS 7.0.6.
Battery indicator stuck until restart iPhone 4S users reported problems with the battery indicator, which would freeze at the same value until the iPhone was restarted.
Touch ID In iOS 7.1, Touch ID was not functioning on the iPhone 5S. The problem could not be resolved by turning Touch ID on and off in the "Fingerprint and Passcode" menu, restarting, resetting, or restoring the device using iTunes. This issue was fixed in iOS 7.1.1.
iOS 8
HealthKit Shortly after the release of iOS 8, Apple released a statement pointing out that a bug had been found in the operating system which prevented HealthKit-compatible apps from being released alongside iOS 8. Apps already released that included HealthKit functionality were withdrawn from the App Store. iOS 8.0.1/8.0.2 included a fix for this issue.
iPhone 6 cellular issues iPhone 6 and iPhone 6 Plus users who updated to iOS 8.0.1 wirelessly had cellular service and Touch ID disabled due to a software issue. Over-the-air downloads of iOS 8.0.1 were stopped within an hour of the release of the software, but many early adopters had been affected. These issues were fixed with the release of iOS 8.0.2 a day later.
Touch ID Users who updated phones with Touch ID enabled to iOS 8.3 found out that they could not use Touch ID to make App Store purchases. A workaround was devised by users to repair this issue.
Performance Many users of older generation devices such as the iPhone 4S and the iPad 2 reported performance issues with iOS 8. iOS 8.1.1 addressed the problem.
Keyboard Several issues with the new Keyboard API in iOS 8 were reported, including problems with custom keyboards crashing or not appearing, or being replaced with the default keyboard. iOS 8.3 addressed the problem.
iMessage When a specific sequence of Arabic, Unicode, and English characters were sent through iMessage to a device running iOS 8.0 through iOS 8.3, it caused the device to crash and restart; if the Messages app was then opened, the crash repeated. This bug, which had existed since iOS 6 but had previously had little impact, was reported by a Reddit user in May 2015 and prompted a lot of such messages to be sent deliberately. This issue was resolved in iOS 8.4, released on July 1, 2015.
iOS 9
Game Center Many users reported greatly increased Game Center loading times which in turn caused apps that used Game Center logins to appear to load slowly. This was fixed with the release of iOS 9.1.
January 1, 1970