iOS Technical Test 2015

1. True or False? When you create a new iOS project from a template, the template automatically makes a controller object for you.

Answers:

• True

• FALSE

2. Automatic migration between Core Data model versions is sufficient for many cases. Which one of the following cases would require additional migration code?

Answers:

• A mandatory attribute is made optional

• An optional attribute is made required

• A relationship has changed from a 'to-one' to a 'to-many' relationship

• A new attribute has been added to an Entity

3. In Objective C, which of the following is group of objects that can be visualized as a physical set of frames?

Answers:

• The stack

• The heap

• The frame

• The set

4. How would you add a property to an Objective C Category?

Answers:

• Create an ivar in the interface definition of the category

• Create an @property definition with @synthesize

• It is not possible to add properties to a category

• Add an associated reference to the category

5. What is the minimum iOS version you can support and still have Automatic Reference Counting?

Answers:

• iOS 5

• iOS 4

• iOS 6

• iOS 3

6. What would be the localized resource name for French?

Answers:

• french.lproj

• fr.plist

• fr.lproj

• fr.local

7. In Objective C, what class will allow you to use one or more blocks concurrently?

Answers:

• NSBlock

• NSBlockOperation

• NSConcurrency

• NSConcurrentBlock

8. What is the effect of using 'weak' in the following @property definition: @property (nonatomic, weak) SomeClass *responder; ?

Answers:

• The responder object is retained and the pointer is set to nil when the object is destroyed

• The responder object is retained and the pointer will point to free memory when the object is destroyed

• The responder object is not retained and the pointer will point to free memory when the object is destroyed

• The responder object is not retained and the pointer is set to nil when the object is destroyed

9. In Core Data, what is the object representation of a record called?

Answers:

• NSManageObjectContext

• NSManagedObjectModel

• NSManagedObject

• NSEntityDescription

10. What flag prevents the device from turning off wifi if your app is running?

Answers:

• Airplane Mode

• UIRequiresPersistentWiFi

• NSWifi

• UINetworkFlag

11. Which 3D Framework was added in iOS since iOS 8?

Answers:

• CoreAnimation

• CoreGraphics

• SceneKit

• Quartz

• SpriteKit

12. In Objective C, what happens when you send a message to a variable that is nil?

Answers:

• Nothing happens

• None of these

• You will receive an error message

• You will receive a confirmation

13. Which of the following statements is TRUE?

Answers:

• When using Grand Central Dispatch your app is assigned three Serial dispatch queues

• (none of these are correct)

• When using Grand Central Dispatch you can create as many serial dispatch queues as you want

• When using Grand Central dispatch only three Serial dispatch queues can operate concurrently

14. How can you make the following code display with rounded corners?   UIView *rectView = [[UIView alloc] initWithFrame:CGRectMake(0, 0, 100, 100)];          rectView.backgroundColor = [UIColor redColor];          rectView.layer.cornerRadius = 8;      [self.view addSubview:rectView];

Answers:

• [rectView setNeedsDisplay];

• [rectView drawRect:rectView.bounds];

• rectView.layer.masksToBounds = YES;

• rectView.roundedCornersVisible = YES;

15. What object is responsible for launch time initalization and transitions?

Answers:

• viewDidAppear

• viewDidLoad

• Main.m

• AppDelegate

16. Which of the following best describes the differences between iOS 7 and iOS 6?

Answers:

• iOS 6 is not supported on iPhone 5s and iPhone 5c

• iOS 7 supports Autolayout.

• iOS 7 user interface has been completely redesigned.

• iOS 7 user interface has been completely redesigned and has 64-Bit Support.

17. What structure can be used to define a portion of a series?

Answers:

• NSRange

• NSString

• NSSet

• CGPoint

18. Which of the following code snippets would work for changing the position of a view?

Answers:

• view.frame.x = 0; view.frame.y = 100;

• view.frame.size.x = 0; view.frame.size.y = 100;

• (none of these)

• CGPoint center = view.center; center.x = 0; center.y = 100; view.center = center;

19. Which of the following objects is considered "the managers in an application" by keeping the other objects in sync?

Answers:

• Model objects

• View objects

• All of these

• Controller objects

20. Which of the follow statements is TRUE of the use of categories?

Answers:

• You can also use categories to split the implementation of a complex class across multiple source code files.

• The syntax to declare a category uses the @protocol keyword.

• A category can only be declared for abstract classes.

• The compiler synthesises any instance variable or property accessor methods for the category.

21. What is used to sort Core Data results?

Answers:

• NSCoreDataSort

• NSSortDescriptor

• NSSort

• [self sort]

22. What class supports the sharing of small amounts of data such as strings or dates to iCloud?

Answers:

• NSUrlConnection

• NSOperation

• NSUbiquitousKeyValueStore

23. What is the preferred way to store paths to files?

Answers:

• NSURL

• fileWithPath

• NSFile

• NSSystemResource

24. When do you use the "assign" value for a property?

Answers:

• On strings

• For primitive values such as BOOLs or NSIntegers

• Never. It should always be either: atomic, nonatomic, strong or weak

• On arrays and dictionaries

25. Delegation is an object-oriented approach to:

Answers:

• delegation

• callouts

• callbacks

• calls

26. In order to test your application in XCode, which testing frameworks are available?

Answers:

• OCMock, OCUnit, XCTest

• (all of these)

• MinUnit, IOSUnit

• NUnit, JUnit

• Tes.ting

27. What do you use to expose preferences for your app in the Settings section of the device?

Answers:

• Variables.bundle

• settings.m

• NSSetting

• Settings.bundle

28. Which of the following holds data and knows nothing about the user interface?

Answers:

• All of these

• View objects

• Model objects

• Controller objects

29. Which statement is NOT true of notifications?

Answers:

• Notifications are identified by the name instance method

• Objects register with a notification center to receive notifications

• Notifications must be registered on the App Delegate

• Notifications are used to broadcast messages to possibly several recipients unknown from the sender

30. What is a design pattern?

Answers:

• A methodology for approching database design

• A template for a solution to a common problem faced by programmers

• Coding standards used by an organization

31. What is a persistent object store?

Answers:

• It is the relationships between tables in your data

• It represents an external file of persisted data.

• It is retained database objects

• It is the schema for your object

32. What data type do you initialize if you want a list of items that can change?

Answers:

• NSDictionary

• NSArray

• NSMutableDictionary

• NSMutableArray

33. What function do you call to close the current view and go back to the root?

Answers:

• pushRootViewController

• popToMainViewController

• closeCurrentView

• popToRootViewController

34. What are the two types of predicates?

Answers:

• Expression and Operator predicates

• Comparison and Compound predicates.

• Filter and exclusion predicates

35. What is a SEL?

Answers:

• The C type of a message selector

• A pointer to a method

• A selection

• The C type of a class

36. Which of the following lines of code will cause a run time crash?

Answers:

• NSArray *array = @[ @"1", @"1", @"2", @"YES" ];

• NSArray *array = [NSArray arrayWithObject:nil];

• NSDictionary *dict = [NSMutableDictionary dictionary];

• NSNumber *num = [NSNumber numberWithInt:[NSNumber numberWithInt:1]];

37. True or False: You can weak link to an entire framework?

Answers:

• True

• False

38. If you use threading, on which thread should UI Transitions be called?

Answers:

• The background thread

• Any thread

• Concurrent threads

• The main thread

39. True or False: You need to call retain on ARC enabled properties

Answers:

• False

• True

40. What is a category?

Answers:

• A category is a way to add methods to a class which already exists

• A way to add instance variables to a class which already exists

• A namespace

• A group of classes

41. True or False: viewDidLoad comes after viewDidAppear?

Answers:

• False

• True

42. True or False: A Collection View is another name for a tableView

Answers:

• True

• False

43. What is the function in Objective C that determines what is in the cells of a tableView?

Answers:

• cellForRowAtIndexPath

• cellForTableView

• tableView.cell.content

• tableViewCellContents

44. True or False: You can use %@ to specify a dynamic property in Objectve C.

Answers:

• True

• False

45. What protocol is used to create an action object?

Answers:

• None of these

• CAAction

• CoreAnimation

• NSAction

46. When using ARC, how do you destroy an object in Objective C?

Answers:

• All of these

• Set the variable that points at it to 1

• Set the variable that points at it to 0

• Set the variable that points at it to nil

47. Can two different applications have the same Identifier For Vendor (aka IDFV)?

Answers:

• Yes, because the vendor of the IDFV is defined by the first two parts of the reverse DNS formatted CFBundleIdentifier

• No, the Identifier For Vendor is generated by the association of an application installation and a device

48. How can you temporarily disable layer actions in a Core Animation?

Answers:

• Using the CAExit class

• Using the CATransaction class

• Using the CAStop class

• Using the CAStopAnimation class

49. NSXMLParser is which kind of parser ?

Answers:

• DOM Parser

• SAX Parser

50. What happens if you use fgets and do not give it a size smaller than the buffer?

Answers:

• It will clip its size automatically

• None of these

• It will use the size of the object as its size

• It will overwrite the data past the size

51. This code doesn't do much, but which line will call the + (void)initialize method on the class SomeClass  1. - (void)doSomething 2. { 3.  [SomeClass someClassMethod]; 4.          SomeClass *obj = [[SomeClass alloc] init]; 5.    NSString *descriptionString = [obj getNewString]; 6. }

Answers:

• line 3

• line 4

• line 5

• line 1

52. In Core Data, what is the name of the object representation for the database schema?

Answers:

• NSManagedObjectModel

• NSEntityDescription

• NSManageObjectContext

• NSManagedObject

53. In Objective C, when an application launches and runs the 'main' function, the frame for 'main' is put at the _____ of the stack.

Answers:

• bottom

• top

54. True or False: In Objective C, all instance methods are accessors.

Answers:

• TRUE

• False

55. In which scenario should you use an NSDictionary over an NSArray?

Answers:

• When item retrieval should be fast and in constant time

• When insertion time should be fast

• When storing literals

• It does't matter, they're both data structures and can be used interchangeably

56. Which instrument would be most suited to debug whether a view is drawn from cache or redrawn?

Answers:

• Time Profiler

• Open GL ES Driver

• Zombies

• Core Animation

57. Which of the following is true?

Answers:

• A class cannot implement more than one protocol

• A class cannot be declared as abstract

• Instance variables must begin with underscore

• Instance variables have to be declared in the header file containing the class definition

58. True or False: The main thread handles touch inputs

Answers:

• True

• False

59. What's the difference between a frame and bounds?

Answers:

• It's the same

• Frame is for UIKit objects, bounds are for CoreGraphics.

• Bounds origin is always (0, 0), a frame origin is relative to his container view

60. What structure can hold an x and y coordinate that defines a location?

Answers:

• CGSize

• CGRect

• CGPoint

• NSFrame

61. What do you do when you don't need a reference on a object ?

Answers:

• [obj free]

• [obj dealloc]

• free(obj)

• [obj release];

62. Is it possible to make a full application without using Interface Builder?

Answers:

• Yes, on any platform

• Yes, but only for iPad

• No, you always have to use Interface Builder to meet Apple's app standards

63. Which of the following objects is visible to the user?

Answers:

• Controller objects

• None of these

• Model objects

• View objects

64. What data object can store a timestamp the best?

Answers:

• NSNumber

• NSString

• NSDate

• NSArray

65. What file contains configuration data for the app?

Answers:

• Main.m

• config.m

• AppDelegate.h

• Info.plist

66. An indexPath has a Section and a ____

Answers:

• Row or item

• Grid

• Coordinate

• Column

67. What is Class Extension?

Answers:

• A class extension is used to declare additional interface -- methods and properties -- whose implementation contract will be met within the class's primary @implementaiton

• Extension of class in Objective-C.

68. What data type do you initialize if you want a string that can change?

Answers:

• NSCore

• NSString

• NSChangeableString

• NSMutableString

69. Methods and instance variables are declared in the ______ file, but the actual code for the methods is placed in the _______ file.

Answers:

• implementation, header

• implementation, implementation

• header, header

• header, implementation

70. The archive that holds the saved create and configure view objects is known as:

Answers:

• XIB

• XBI

• XID

• XML

71. If an asset is for iPad only, how do you specify it in the file name?

Answers:

• !iPad

• ~iPhone

• !iPhone

• ~iPad

72. ARC Stands for:

Answers:

• Automatic Retained Collections

• Automatic Reference Counting

• Allocated Reference Cycles

• Autoreleased Reference Counters

73. Which of the following symbols do you prefix a character string with when you want a hard coded string?

Answers:

• @

• *

• &

• #

74. What's the difference between NSArray and NSMutableArray?

Answers:

• NSArray has a limited capacity of 256 items where as NSMutableArray is unlimited

• NSMutableArrayʼs contents can not be modified once itʼs been created whereas a NSArray can be modified as needed

• NSArray is an abstractClass class and NSMutableArray is a protocol

• NSArrayʼs contents can not be modified once itʼs been created whereas a NSMutableArray can be modified as needed

75. How do you reference your app bundle?

Answers:

• app.io

• self.app.fileSystem

• self.bundle

• [NSBundle mainBundle]

76. What is a delegate?

Answers:

• A delegate is a UIView

• A delegate allows one NSObject to send messages to another NSObject, and listen to those messages

• A delegate is a variable

• A delegate holds the type of data a variable stores

77. What function is called for each cell in a Table View?

Answers:

• cellDidAppear

• viewDidLoad

• viewWillLoad

• cellForRowAtIndexPath

78. Which of the following keyboard shortcuts will run your app on the simulator?

Answers:

• Command-P

• Command-A

• Command-R

• Command-G

79. What is @2x used for?

Answers:

• Retina Assets

• Normal Assets

• NSStrings

• All Images

80. True or False? An object with at least one owner can be destroyed.

Answers:

• True

• False

81. What is the name of the type of SQL Database that iOS Supports?

Answers:

• SQL

• SQLite

• MySql

• NoSql

82. Which scenario will not result in NSOperation throwing an exceptions:

Answers:

• When you try to retrieve the result of an NSInvocationOperation object that was canceled.

• When the operation is not ready to execute but its start method is called.

• When the return value from a completion block is nil.

• When the operation is executing or finished (possibly because it was canceled) and its start method is called again.

• When you try to add a completion block to an operation that is already executing or finished.

83. When adding objects to NSMutableDictionary, the key...

Answers:

• Must be wither an NSString or an NSNumber

• Must be a string literal

• Must conform to the NSCopying protocol

• Can be any object

84. What class can implement Document Objects?

Answers:

• NSDocument

• NSUrl

• NSArray

• UIDocument

85. Which one of the following is true?

Answers:

• None of these are true

• You can modify UIKit drawing on a background thread

• You can modify Core Animation layers on a background thread

• You can only create and draw to an image context on the main thread