iPad 
How iOS decides which wireless network to auto-join
iOS follows these guidelines when deciding which wireless network to auto-join.
If you can’t back up or restore your iPhone, iPad, or iPod using iTunes
If you see an alert message in iTunes that your device cannot be backed up or restored, try the steps in this article.
Redeem iTunes Gift Cards with the camera on your iPhone, iPad, iPod touch, or Mac
Learn to use the camera on your iPhone, iPad, iPod touch, or Mac to redeem iTunes Gift Cards.
Use Passbook in iOS
Use Passbook to keep your boarding passes, movie tickets, coupons, loyalty cards, and more in one place.
iBooks: Tips for managing your iBooks library and storage on iOS devices
Learn about managing your iBooks library and storage on your iOS devices.
iCloud, iPhone, iPad, and iPod touch: Some of my emails/updates don’t seem to be pushed to my device
When you read, delete, reply to, or move a message on one device, your iPhone, iPad, or iPod touch does not appear to update automatically.
Find My Friends: Frequently asked questions
Find My Friends is a free app for iOS 8 or later that allows you to easily locate your friends and family from your iPhone, iPad, or iPod touch.
나의 친구 찾기: 자주 묻는 질문
나의 친구 찾기는 iPhone, iPad 또는 iPod touch에서 친구와 가족을 쉽게 찾을 수 있게 해 주는 iOS 8 이상용 무료 App입니다.
