Objective C interview questions

Q1.What  is property?
Ans:Properties are used  to  access  the  instance  variables  from  outside  of  class.
Q2. What  is synthesized?
Ans:After  you  declare  the  property  in objective-c .  we  have to tell  the  compiler instantly  by  using  synthesize  directive. Actually  this  tells  to compiler  to generate  a  getter&setter  message.
Q3.What  is nonatomic?
Ans:

Q4. What is retaining?
Ans:It is reference count of the object
Q5. What is webservice?
Ans:Main  purpose is  to expose the data  in  form  of xml  format  ,by  using  this  we  can  getting  the  data  from  server.
Q6. What  is parsing?
Ans:To  access the data  in the  xml  element  is called  parsing.
Q7.Which class  we  can  use  for  passing  of xml  in  iphone?
Ans:By  “NSXML” Parser.
Q8.Which  type of  parse  we  have  use  in  iphone?
Ans:”SAX” parser.

Q9.Which  class are used to establish  connection  b/w application to webserver?
Ans:(a)NSURL
        (b)NSURL REQUEST
        (c)NSURL CONNECTION.
Q10.What  is difference between DOM&SAX?
Ans:(a)Dom is a documents based parser.
When we will work with these parser all the data of xml is stored in RAM.                                                          In this parser  “memory consumption” is more.

(b)SAX  is  a  event  driven parser.When we will work with these parser,take only  reference  from  xml file  and  generate  the        oneevent  for  every element.

Q11.After  parsing  if  you  want  to  get your data in  view  which  delegation  methods  are  did  you use?
Ans:(a)did  start  element      (b)did  end  elemen        (c)found  character.

Q12.How many  methods  are  used  in  NSURLConnection?
Ans:I  have 4 types methods
(a)Connection  did  receive  Response
(b)Connection  did  recevice  Datat
(c)Connection  fail  with error
(d)Connection  did  finish loading.

Q13.Tell  me  about  json-parser?
Ans:”JSON” Means  “Java script object notation”.
           It is a one  type  of  parser (or)test-based  and  hightweight  parser.

Q14.By  default application which  things  contain?
Ans:In ipone applications  by  default  having 3 things
1.main→It is  entry  point of  application.
2.Appdelegate→It is  perform  the  basic application  &  functionality.
3.Window→It  is  provide  uiinterface.

Q15.What is  uiviewcontroller?
Ans:   uiview controller  is base class for all the controller.

Q16. What is the navigation controller?
  Ans: Navigation  controller contains the stack of controllers every navigation controller
         must be having root view controller by default these controllers contain 2 method
         (a) push view      (b) pop view
        By default navigation controller contain “table view”.


Q17. What is tab bar controller?
 Ans: Tab bar is used to common way to display the data on iphone.


Q18. What is the table view controller?
Ans: Table view controller contains the number of rows and columns visible in the
        application  and makes a cell editable or not as a response to key press



Q19. Which protocols are did used in table view? Ans: Table view contain 2 delegate protocols
      (a). Ui table view data source
              (b). Ui table view delegate.
         In ui view table view data source contain these methods
               (a). No of sections.
               (b). No of rows in sections.
               (c). Cell for row index path row.
        In ui table view delegate contain these methods
               (a). Did select row at index path row


Q20. By default table view which controller contain?
Ans: Detail view controller that is present is ui table view delegate


Q21.  What is the split view controller?
Ans: This control is used for ipad application and it contain proper controllers by default
         split view controller contain root view controller  and detail view controller.


Q22.  What are data base are used in iphone?
Ans: (a). Sql lite (b). Plist c). Xml (d). core data
          (

Q23. Tell me about the MVC architecture?
Ans: M-model, V-view, C-controller
         Main advantage of MVC architecture is to provide “reusability and security”
         by separating the layer by using MVC architecture.

         Model: it is a class model is interact with database.
         Controller: controller is used for by getting the data from model and controls the views.
         Viewdisplay the information in views.

Q24. What are frame works are used in iphone?
Ans:       (a). Ui kit framework
               (b). Map kit framework
               (c). ADI kit framework
               (d). Core data framework
               (e).core foundation framework

Q25. What is the instance methods?
Ans: Instance methods are essentially code routines that perform tasks so instances
        of clases we create methods to get and set the instance variables and to display
         the current values of these variables.

Declaration of instance method :
          - (void)click me: (id)sender;
          Void is return type which does not giving any thing here.
          Click me is method name.
          Id is data type which returns any type of object.


Q26. What is the class method?
Ans: Class methods work at the class level and are common to all instance of a
         class these methods are specific to the class overall as opposed to working
         on different instance data encapsulated in each class instance.
@interface class name :ns object
         {
          }
 +(class name *)new alloc:
 -(int)total open



Q27. What is data encapsulation?
Ans: Data is contained with in objects and is not accessible by any other than
         via methods defined on the class is called data encapsulation.

Q28. What is accessor  methods?
Ans: Accessor methods are methods belonging to a class that allow to get and set
         the values of instance valuables contained with in the class.

Q29. What is synthesized accessor methods?
Ans: Objective-c provides a mechanism that automates the creation of accessor
         methods that are called synthesized accessor methods that are
implemented through use of the @property and @synthesized.



Q30. How to access the encapsulated data in objective-c?
Ans:(a)Data encapsulation encourages the use of methods to +get and set the values
              of instance variables in a class.
        (b)But the developer to want to directly access an instance variable with out   having to go through an accessor method.         (c) In objective-c syntax for an instance variable is as follow     [class instance variable name]


Q31. What is dot notation?
Ans: Dot notation features introduced into version 2.0 of objective-c
         Dot notation involves accessing an instance variable by specifying
         a class “instance” followed by a “dot” followed in  turn by the name of instance variable or property to be accessed.

Q32. What is single inheritance in objective-c?
Ans: Objective-c subclass can only be derived from a single direct parent class this s concept is called as “single inheritance”.

Q33. Ns object is parent class or derived class?
Ans: Ns object is parent class and contains a number of instance variables and  instance methods.

Q34. How to call function in objective-c
Ans:   [account display account info]
           Account-> object name
           Display account info-> method name