21⟩ 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.
iPhone
Home Mobile Technologies iPhone
“iPhone frequently Asked Questions by expert members with experience in iPhone . These interview questions and answers on iPhone will help you strengthen your technical skills, prepare for the interviews and quickly revise the concepts. So get preparation for the iPhone job interview”
52 IPhone Questions And Answers
22⟩ Tell me 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.
23⟩ 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.
24⟩ 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.
25⟩ What are the popular apps of iPhone?
Face book-Social networking
Doodle Buddy-drawing
Pandora Radio-radio on our iPhone
Yelp-restaurant reviews
26⟩ Do you know 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.
27⟩ Explain 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.
28⟩ 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.
29⟩ 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.
30⟩ What are the tools required to develop iOS applications?
iOS development requires Intel-based Macintosh computer and iOS SDK.
31⟩ Name the framework that is used to construct application’s user interface for iOS?
The UIKit framework is used to develop application’s user interface for iOS. UIKit framework provides event handling, drawing model, windows, views, and controls specifically designed for a touch screen interface.
32⟩ Explain 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.
33⟩ Do you know 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.
34⟩ When an app is said to be in not running state?
An app is said to be in 'not running' state when:
it is not launched.
it gets terminated by the system during running.
35⟩ How can you respond to state transitions on your app?
On state transitions can be responded to state changes in an appropriate way by calling corresponding methods on app's delegate object.
For example:
application Did Become Active method can be used to prepare to run as the foreground app.
application Did Enter Background method can be used to execute some code when app is running in the background and may be suspended at any time.
application Will Enter Foreground method can be used to execute some code when your app is moving out of the background application Will Terminate method is called when your app is being terminated.
36⟩ Assume that your app is running in the foreground but is currently not receiving events. In which sate it would be in?
An app will be in InActive state if it is running in the foreground but is currently not receiving events. An app stays in InActive state only briefly as it transitions to a different state.
37⟩ List down apps state transitions when it gets launched?
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.
38⟩ Who calls the main function of you app during the app launch cycle?
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.
39⟩ Give example scenarios when an application goes into InActive state?
An app can get into InActive state when the user locks the screen or the system prompts the user to respond to some event e.g. SMS message, incoming call etc.
40⟩ When an app is said to be in active state?
An app is said to be in active state when it is running in foreground and is receiving events.
