iOS

Before the launch of an app, it is said to be in not running state.

When an app is launched, it moves to the active or background state, after transitioning briefly through the inactive state.

On state transitions can be responded to state changes in an appropriate way by calling corresponding methods on app's delegate object.

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.

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.

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.

You can choose whether to have photos resized for faster uploading. You can choose between predefined dimensions (small/medium/large) or setting a custom resize dimension.

Yes. On WordPress.com blogs, all communication (done over XML-RPC) is by default going to use an encrypted connection via SSL. For self-hosted WordPress, if you have SSL enabled, WordPress 2.6.1 or later supports pointing the RSD information at the “https” version of xmlrpc.php which creates an encrypted communication link with the App.

multitasking is supported through seven background APIs:

Background audio – application continues to run in the background as long as it is playing audio or video content

Voice over IP – application is suspended when a phone call is not in progress

Background location – application is notified of location changes

Push notifications

Local notifications – application schedules local notifications to be delivered at a predetermined time

Task completion – application asks the system for extra time to complete a given task

Fast app switching – application does not execute any code and may be removed from memory at any time

The iOS kernel is XNU, the kernel of Darwin. The original iPhone OS (1.0) up to iPhone OS 3.1.3 used Darwin 9.0.0d1. iOS 4 was based on Darwin 10.0.0. iOS 5 was based on Darwin 11.0.0. iOS 6 was based on Darwin 13.0.0. iOS 7 is based on Darwin 14.0.0

In iOS 4.0 to iOS 6.x, double-clicking the home button activates the application switcher. A scrollable dock-like interface appears from the bottom, moving the contents of the screen up. Choosing an icon switches to an application. To the far left are icons which function as music controls, a rotation lock, and on iOS 4.2 and above, a volume controller. Holding the icons briefly makes them "jiggle" (similarly to the homescreen) and allows the user to force quit the applications by simply tapping the red minus circle that appears at the corner of the app's icon.

Where to begin? The entire look and feel of the system has been overhauled, with flatter icons, less skeumorphism, and thinner typefaces. That said, anybody who’s used iOS will probably feel mostly at home: Apple hasn’t changed the home screen much, and the basic gestures and interactions are largely the same, with a few new exceptions.

How did you feel about green felt? Wood bookshelves? Stitched leather? I hope the answer is “not great,” because they’re all gone in iOS 7. Instead they’ve been replaced with a new cleaner design that’s largely about simple lines and icons. While there are elements reminiscent of Microsoft’s recent Windows Phone design, iOS 7 clearly has its own distinct style. These aren’t just subtle enhancements either; they permeate every bit of the interface.

Not really. Launching and using apps is largely the same. But there will be some new things to learn. For example, you can now swipe up from the bottom of the screen to summon Control Center (a handy panel that gives you access to many of your most commonly-used system features). There’s another new swipe-from-the-left-edge gesture that means “go up a level” when you’re in Mail, for example.

Very carefully. Spotlight’s moved from its traditional home on a separate home screen. With iOS 7, you’ll trigger searches by pulling from the center of the screen and essentially dragging your home screen downward. It’s a weird gesture to learn at first.

There are new ringtones and alert options with iOS 7, if that’s the sort of thing that sets your pulse racing.

Apple’s spent a lot of time making sure that battery life won’t suffer from the new multitasking. It tries to collect updates from different apps and run them all at the same time, and keeps an eye on both power efficiency and the current network situation to make sure it doesn’t run down your battery.

Like the rest of iOS 7, Camera’s gotten a significant overhaul. It offers four different modes: standard camera, video camera, a square camera, and panorama; you can swipe back and forth between them. If you think that square camera might be Apple’s way of taking a shot at Instagram, congratulations: You’re spot on. The app also now includes different live photo filters that you can apply to your still or square shots. They’re even non-destructive, in case you want to remove them later.