Apple Technical Interview Questions & Answers

Question 1. Explain Popular Apps Of Iphone?

Answer :

Face book-Social networkingDoodle Buddy-drawingPandora Radio-radio on our iPhone Yelp-restaurant reviews.

Question 2. What Could Be Performance Hits For Searching On Local Computer I.e. If You Are Searching Computer For Content What Are The Parameters You Will Consider For Performance?

Answer :

I think we need to think about filesystems and other OS components.Not everything in computer is implemented using hast table.In case of spotlight if you see wiki the underlying data structure is B trees.Think in that direction what factor apart from B trees would be a performance hit.Hint: think about filesystems.

Question 3. Explain Iphone Architecture?

Answer :

It is similar to MacOS 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.

Question 4. Explain Differentiate Between Google Search And Local Computer Search?

Answer :

google search is global serach engine based on out side information,local computer search is with in computer area data or information search.

Question 5. Please Explain The Difference Between Shallow Copy And Deep Copy?

Answer :

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.

Question 6. How To Test Ios Simulator? Or How Would You Test An Android Simulator? Note: The Questions Asks For How Would You Test The Simulator Itself And Not Applications?

Answer :

Two methods must be applied. First, the simulator must conform to the system specification for the hardware. Every instruction that retires must behave exactly as the hardware expects, including every result, and every control register. Unit tests can be written for these individual cases and used to maintain the simulator. Next, real world programs and applications should be ported to run on the simulator. Instrumentation code can be added to provide some kind of checksum section to ensure that the simulator is outputting results the same as hardware.

Question 7. Explain The Requirements For Developing Iphone Apps?

Answer :

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

IPhone SDK consists of:

1. IDE to develop iPhone Apps is XCode(This tool is inbuilt in iPhone SDK)
2. Interface Builder This is used to design GUI of Apps(Inbuilt feature of iPhone SDK)
3. Instruments This is used to check any memory leaks in our apps (Inbuilt in SDK)
4. Simulator This is used to test our apps before deploying into real device.

Question 8. What Is B Trees And Its Applications?

Answer :

A B-tree is just another tree data structure mostly used within file systems and databases. Common file systems that use B-trees are HFS+ (OSX), ext4 (Linux) and NTFS (Windows).

Question 9. Define About The Applications That Can Be Used With Iphone?

Answer :

Technology, Entertainment and Design(TED): 

Allows to watch and listen to world's most fascinating people have to say, all on the iPhone.

Market Watch: 

Breaking news about the investments can be seen. To do so, open the Stocks app and rotate.

Trends: 

Latest runway shows, videos from Vogue's fashion library, reviews, exclusive party pictures, fashion news updates can be seen on Style.com.

Question 10. How To Design Spotlight Search Feature In Mac Os?

Answer :

B-tree or Hash Table

Question 11. Where Can You Test Apple Iphone Apps If You Do Not Have The Device?

Answer :

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.

Question 12. Do You Know Which Sorting Algo You Would Like To Implement As Unix Library And Why?

Answer :

I think more than the answer, the reason would be important. Quick sort for example is important because its average runtime is O(nlog(n)) and in most cases its better than other logarithmic algorithms ( Merge Sort and Heap Sort ). I would ask him though, why would you want to stop at implementing just one algorithm. How about an API that can use sort based on input size ( strategy design pattern ); because for different values of n different sorting algorithms can be usefule.

Question 13. Explain Which Json Framework Is Supported By Ios?

Answer :

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.

Question 14. How To Parse A Phone Number From A Huge Database Of A N Billion Webpages In 30 Minutes?

Answer :

The numbers do have sematic meaning, eg: location. Hence, if the database is distributed, that helps. Additionally, the DB must be stored in a N-nary search tree where N is large, reducing the height of the tree significantly.

Question 15. Explain Does Ios Support Multitasking?

Answer :

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.

Question 16. Designed A Similar Api Like Malloc, Which Has A Similar Functionality. How Do You Test The Api?

Answer :

1.  Give a very large size(1000000000) and check if its able to allocate
2.  Provide number values 1,3,0,100
3.  Give a character in size to api
4.  GIve blank spaces
5.  NUll value for size field in api
6.  Call the api from multiple sessions

Question 17. Explain Fast Enumeration?

Answer :

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 pipelining potential.)

Question 18. Suppose If There Are Two Threads In Your App - T1 And T2. T2 Has High Priority. However, For Some Reason The Priority Decreases Automatically. What Could Be The Reason? How Will You Debug It? How Will You Fix It So That Pririty Stays The Same, No Matter What?

Answer :

Poll after some constant time If T1 has priority p always set T2 priority lesser then T1 that is p+1.

Question 19. The Producers Write Elements To A Ring Buffer(fixed Size) While The Consumers Access Elements From It. Implement A Write And A Read Function Using A Producer Pointer And Consumer Pointer. The Consumer Pointer Cannot Surpass The Producer Pointer And When The Producer Pointer Reaches Where It Starts Again, It Stops?

Answer :

How about this? For multithreading, put mutex in write

template<typename T>

class writeandread

{

public:

writeandread(T* s, int n):start(s), writePtr(s),readPtr(s), maxbytes(n), numofeles(0) {}

T* getStartPtr(){return start;}

T* getwritePtr(){return writePtr;}

T* getreadPtr(){return readPtr;}

bool write(T* input, int n);

T* read(int n);

private:

T* start, *writePtr, *readPtr;

size_t maxbytes, numofeles;

};

template<typename T>

bool writeandread<T>::write(T* input, int n)

{

if (input == NULL && n > 0)

return false;

if (maxbytes-numofeles < n*sizeof(T)/sizeof(char))

return false;

numofeles += n*sizeof(T)/sizeof(char);

for (int i = 0; i < n; ++i)

{

*writePtr = *input;

++writePtr;

++input;

}

return true;

}

template<typename T>

T* writeandread<T>::read(int n)

{

if (n <= 0)

return NULL;

T* res = (T*) malloc(n);

T* t = res;

int count = 0;

while (writePtr != readPtr)

{

*t = *readPtr;

++t;

readPtr += sizeof(T);

++count;

}

if (count < n)

readPtr = start;

return res;

}

Question 20. Explain Why Iphone Apps Are Popular?

Answer :

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.

Question 21. Explain Iphone?

Answer :

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.

Question 22. Tell Me How Many Bytes We Can Send To Apple Push Notification Server?

Answer :

256 bytes.

Question 23. Explain Iphone Os?

Answer :

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.

Question 24. Explain Iphone Application Development?

Answer :

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.

Question 25. Explain Iphone Sdk?

Answer :

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.

Question 26. Tell Me Does Multitasking Support Is Available From Which Version?

Answer :

iOS 4.0.

Question 27. Explain Sensors In Iphone?

Answer :

The proximity sensor immediately turns off the display when the iPhone is lifted to ear. With this sensor the power is saved and accidental dialing is prevented. The display is automatically brightens the iPhone by the ambient light sensor when the sunlight or bright rooms and dims in darker places.

Question 28. Explain Frame And Bounds?

Answer :

The frame of a view is the rectangle, expressed as a location (x,y) and size (width,height) relative to the superview 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).

Question 29. Define The Features Of Iphone 3gs?

Answer :

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

3 Megapixel 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.

Question 30. Explain An Iphone App?

Answer :

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.

Question 31. Explain Iphone Reference Library?

Answer :

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 Xcode, and click the subscribe button next to the iPhone OS Library doc set, which appears in the left column.

Question 32. Explain Struct?

Answer :

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

Question 33. Define The Location Services?

Answer :

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.

Question 34. Explain The Functionality Of Accelerometer Of An Iphone?

Answer :

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.