iphone Interview Questions and Answers

iPhone Interview Questions and Answers 

1. What is iPhone?

iPhone is a combination of internet and multimedia enabled smart phone developed by Apple Inc.

iPhone functions as a camera phone, including text messaging, and visual voice mail

iPhone is a portable media player that resembles a video iPod

It has user interface that is built around the multi-touch screen including virtual keyboard.

App Store , which launched in the mid 2008 has over 1,00,000 applications with functionalities including games, references, GPS navigation, advertising, television shows, films, reference, celebrities.

2.What is an iPhone app?

An iPhone app is a program that runs on our iPhone/iPod Touch. It enables us to accomplish a certain task. They could be utility apps, games, enterprise apps, entertainment apps, apps to access our bank account etc.

3. Introduction to I phone application Development?

In 2007, Apple entered the cellular phone business with the introduction of the iPhone, a multi-touch display cell phone, which also includes the features of iPod.

4. Multitasking support is available from which version?

iOS 4.0

5. How many bytes we can send to apple push notification server.?

256bytes.

6. What are the features of iPhone 3gs?

Video: Videos can be edited, shared. High quality VGA video can be shot in portrait or landscape.

3 Mega pixel Camera: Still photos with greater quality can be taken

Voice control: It recognizes the names in contacts and recognizes the music on iPod.

Compass: iPhone 3GS has built-in digital compass, used to point the way.

Internet Tethering: Internet surfing can be done from anywhere. A 3G connection can be shared on Iphon3 with Mac notebook or laptop

7. Why iPhone apps are popular?

Give our business a whole new way of transacting business for millions of users.

IPhones are the market leaders in the smart phone segment. The iPhone has become a great device to surf the internet, play games, interact with social networks and transact business.

8. Where can you test Apple iPhone apps if you don’t have the device?

iOS Simulator can be used to test mobile applications. Xcode tool that comes along with iOS SDK includes Xcode IDE as well as the iOS Simulator. Xcode also includes all required tools and frameworks for building iOS apps.  However, it is strongly recommended to test the app on the real device before publishing it.

9. Does iOS support multitasking?

iOS 4 and above supports multi-tasking and allows apps to remain in the background until they are launched again or until they are terminated.

10. Which JSON framework is supported by iOS?

SBJson framework is supported by iOS.  It is a JSON parser and generator for Objective-C. SBJson provides flexible APIs and additional control that makes JSON handling easier.

11. What is iPhone OS?

iPhone OS runs on iPhone and iPod touch devices.

Hardware devices are managed by iPhone OS and provides the technologies needed for implementing native applications on the phone.

The OS ships with several system applications such as Mail, Safari, Phone, which provide standard services to the user.

12. Difference between shallow copy and deep copy?

Shallow copy is also known as address copy. In this process you only copy address not actual data while in deep copy you copy data.

Suppose there are two objects A and B. A is pointing to a different array while B is pointing to different array. Now what I will do is following to do shallow copy.
Char *A = {‘a’,’b’,’c’};
Char *B = {‘x’,’y’,’z’};
B = A;
Now B is pointing is at same location where A pointer is pointing.Both A and B in this case sharing same data. if change is made both will get altered value of data.Advantage is that coping process is very fast and is independent of size of array.

while in deep copy data is also copied. This process is slow but Both A and B have their own copies and changes made to any copy, other will copy will not be affected.

13. What are the requirements for developing iPhone Apps?

Mac OS 10.5/10.6 iPhone SDK (Software Development Kit 3.0/4.0).

IPhone SDK consists of:

 IDE to develop iPhone Apps is XCode(This tool is inbuilt in iPhone SDK)

 Interface Builder This is used to design GUI of Apps(Inbuilt feature of iPhone SDK)

 Instruments  This is used to check any memory leaks in our apps (Inbuilt in SDK)

 Simulator This is used to test our apps before deploying into real device. 

14. What are the popular apps of iPhone?

Face book-Social networking

Doodle Buddy-drawing

Pandora Radio-radio on our iPhone

Yelp-restaurant reviews 

15. What is iPhone reference library?

iPhone reference library is a set of reference documents for iPhone OS. It can be downloaded by subscribing to the iPhone OS Library doc set. Select Help>Documentation from X code, and click the subscribe button next to the iPhone OS Library doc set, which appears in the left column.

16. What is iPhone sdk?

iPhone SDK is available with tools and interfaces needed for developing, installing and running custom native applications. Native applications are built using the iPhone OS’s system frameworks and Objective-C language and run directly on iPhone OS. Native applications are installed physically on a device and can run in presence or absence of network connection.

17.What is iPhone architecture?

It is similar to Mac OS X architecture

It acts as an intermediary between the iPhone and iPod hardware an the appearing applications on the screen

The user created applications never interact directly with the appropriate drivers, which protects the user applications from changes to the hardware.

18.What are the location services?

Applications such as Maps, camera and compass are allowed to use the information from cellular, Wi-Fi and Global Positioning System networks for determining the approximate locations.

The location is displayed on the screen, using a blue marker.

19.Describe the functionality of accelerometer of an iPhone ?

iPhone responds to motion using a built-in accelerometer.

The accelerometer detects the movement and changes the display accordingly, at the time of rotating iPhone from portrait to landscape.

20.Name the application thread from where UIKit classes should be used?

UIKit classes should be used only from an application’s main thread.  Note: The derived classes of UIResponder and the classes which manipulate application’s user interface should be used from application’s main thread.

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