iOS Interview Preparation Guide

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The App works with any device that is running iOS version 7 or greater.

1. A common issue that can cause errors with the App is invalid characters. The easiest way to check is to go to the W3C Markup Validator and type in the URL of your WordPress site. If you get a response such as “… one or more bytes that I cannot interpret as UTF-8″ that is most likely what is causing the app to have trouble with your site.
2. You can also try with the default theme and with no active plug-in.
(Trying it with the default theme and plugins disabled will help pin down where the problem is. If everything works then you go back and enable your theme and then try it again. If everything still works then you go back and activate each plugin one at a time until you find the one that is causing the breakage.)

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.

When you are ready to publish, change the status of the post (from the Settings screen) to “Published” and then tap “Save.”

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.

The home screen (rendered by and also known as "SpringBoard") displays application icons and a dock at the bottom of the screen where users can pin their most frequently used apps. The home screen appears whenever the user unlocks the device or presses the "Home" button (a physical button on the device) whilst in another app. The screen's background can be customized with other customizations available through jailbreaking. The screen has a status bar across the top to display data, such as time, battery level, and signal strength. The rest of the screen is devoted to the current application. When a passcode is set and a user switches on the device, the passcode must be entered at the Lock Screen before access to the Home Screen is granted.

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

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.

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

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.

If you’re looking to update to iOS 7 when it lands in the fall, you’ll need to have one of these devices: the iPhone 4 or later; iPad 2 or later; iPad mini; or fifth-generation iPod touch. Oh, and both the iPhone 5s and iPhone 5c announced by Apple will arrive with iOS 7 already installed, though they don’t go on sale until September 20—two days after iOS 7’s release.

Specific features have more stringent device requirements (see below for details on these features):

Panoramic photos are only available on the iPhone 4S or later and fifth-generation iPod touch.
You can’t shoot square photos or video using the iPad 2; all other devices can use this feature, however.
For the nifty new live camera filters, you’ll need an iPhone 5 (including the s and c models) or fifth-generation iPod touch. Putting filters on after the fact in the Photos app is an option for the iPhone 4 or later, third-generation iPad or later, iPad mini, and fifth-generation iPod touch.
To AirDrop a photo or other file to your friends, you’ll need an iPhone 5 or later, fourth-generation iPad or later, iPad mini, or fifth-generation iPod touch. You’ll also need an iCloud account.
Siri continues to be limited to those using an iPhone 4S or later; third-generation iPad or later; iPad mini; and fifth-generation iPod touch. It also may not be available for your country. And if it’s a new Siri voice you desire, keep in mind that it’ll only be available initially in English, French, or German.

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.

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.

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

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.

For those of us that end up with thousands of pictures in our Camera Rolls, Moments and Collections offer a better way to organize those photos. Just as iPhoto on the Mac can automatically break pictures into events, Photos on iOS can use metadata like time and location to create different “Moments”—all the pictures you took on Thursday at dinner, for example, or all the photos you snapped while on that weekend trip to the country. Collections are larger groupings of Moments—often all the photos you took in a general area (around your house) during a time period of often several months. Beyond that you can zoom out even further to a Years view that breaks down all the pictures you took in various (you guessed it) years.

It does! AirDrop in iOS 7 lets you exchange files like pictures, Passbook passes, and contacts between two iOS users over Wi-Fi or Bluetooth, without any configuration and (as Apple’s Craig Federighi pointed out) without the need to walk around and “bump” phones with people. AirDrop appears in the Share sheet, along with more conventional items like Mail and Messages; you can even use it to share multiple items to multiple people at once. Files end up right in the appropriate app and are encrypted during transmission. You can also change permissions to determine whether everybody can share with you, or only certain people nearby (or people in your contacts).

When you build your iOS app, Xcode packages it as a bundle. A bundle is a directory in the file system that groups related resources together in one place. An iOS app bundle contains the app executable file and supporting resource files such as app icons, image files, and localized content.

Fast enumeration is a language feature that allows you to enumerate over the contents of a collection. (Your code will also run faster because the internal implementation reduces message send overhead and increases pipe-lining potential.)

A special C data type that encapsulates other pieces of data into a single cohesive unit. Like an object, but built into C.

NSArrayʼs contents can not be modified once itʼs been created whereas a NSMutableArray can be modified as needed, i.e items can be added/removed from it.

Retain counts are the way in which memory is managed in Objective-C. When you create an object, it has a retain count of 1. When you send an object a retain message, its retain count is incremented by 1. When you send an object a release message, its retain count is decremented by 1. When you send an object a auto-release message, its retain count is decremented by 1 at some stage in the future. If an objectʼs retain count is reduced to 0, it is deallocated.

The frame of a view is the rectangle, expressed as a location (x,y) and size (width,height) relative to the super-view it is contained within. The bounds of a view is the rectangle, expressed as a location (x,y) and size (width,height) relative to its own coordinate system (0,0).