iOS is a mobile (i phone) operating system developed by Apple Inc. and distributed exclusively for Apple hardware. It is the operating system that powers many of the company's i'Devices.
Speaking of hiding images, if you want to hide one of your own just long tap the image and the Copy/Hide dialog pops up. Tap Hide and the image goes dark to show it has been hidden. You can still find it in the Hidden album, but no one else will see it.
All deleted images are now kept for a period in the 'Recently Deleted' album. That's handy if you ever delete things in error, but be sure to Delete All the images in that album if you happen to be a celebrity trying to keep intimate images from leaking online without your permission.
Repeating message alert sounds getting you down? You can switch it off: Settings>Notifications>Messages Scroll to Repeat Alerts and flip this to Never. Now you will only be alerted once when new messages reach you.
If you have multiple Apple devices that all use your Apple ID you may start to receive calls on all your devices at once. You can control this by switching off iPhone Cellular Calls in the Face-time section of each device's Settings menu, but be sure to only disable this in devices you don't want to use for calls.
If the clicks of your iOS 8 keyboard are driving you mad, switch it off in Settings>Sounds>Keyboard Clicks, toggle to off.
Views along with controls are used to provide visual representation of the app content. View is an object that draws content in a designated rectangular area and it responds to events within that area.
Layer objects are data objects which represent visual content. Layer objects are used by views to render their content. Custom layer objects can also be added to the interface to implement complex animations and other types of sophisticated visual effects.
You can switch it off easily: Settings>General>Keyboard and toggle that switch to Off.
During app launching, the system creates a main thread for the app and calls the app's main function on that main thread. The Xcode project's default main function hands over control to the UIKit framework, which takes care of initializing the app before it is run.