Objective-C LinkedIn Skill Assessment Answer

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Here, We see Objective-C LinkedIn Skill Assessment Answer. This assessment test consists of 15-20 MCQs to demonstrate your knowledge of your selected skills. MCQs come from different topics – Classes, Collections, Functions, General, and Variables.

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Objective-C LinkedIn Skill Assessment Answer

Objective-C LinkedIn Skill Assessment Answer

Q1. What is the value of s?

NSMutableString *s = [NSMutableString stringWithString: @"123"];
[s appendString: @"456"];
Code language: JavaScript (javascript)
  •  123456✔
  •  123
  •  123
  •  456
  •  This code contains an error.

Q2. What’s the value of i after these statements?

NSString *str = nil;
NSInteger i = str.integerValue;
  •  nil
  •  0 (technically nil == 0 but i will have a literal value of 0 and not the void* value of nil)✔
  •  -1
  •  This code crashes.

Q3. What value is in str after this line is executed?

NSString str = "test" + " " + "more";Code language: JavaScript (javascript)
  •  This code contains an error✔
  •  test
  •  nil
  •  test more

Q4. What is the output of the code given below?

    NSPredicate *p2 = [NSPredicate predicateWithBlock:^BOOL(NSString*  evaluatedObject, NSDictionary<NSString *,id> * _Nullable bindings) {
      return evaluatedObject.intValue % 2 == 0;
    }];
    NSArray *vals = @[@"1", @"2", @"3"];
    NSArray *n2 = [vals filteredArrayUsingPredicate:p2];
    NSLog(@"%@", n2.firstObject);
Code language: JavaScript (javascript)
  •  2✔
  •  1,2,3
  •  1,2
  •  Nothing, since this code contains an error.

Q5. Property defaults include _?

  •  atomic/strong✔
  •  atomic/weak
  •  nonatomic/weak
  •  nonatomic/strong

Q6. What is the key difference between NSDictionary and NSMutableDictionary?

  •  NSMutableDictionary’s values can change✔
  •  NSMutableDictionary has no initializers.
  •  NSDictionary can’t be copied.
  •  NSDictionary’s values can change.

Q7. What is foo?

-(float)foo;
  •  A function with a return type of float.✔
  •  This code contains an error.
  •  A variable declaration of type float.
  •  A property of type float.

Q8. What can you glean from this line?

#import "NSString+NameHelper.h"Code language: CSS (css)
  •  NameHelper is a category of NSString.✔
  •  NameHelper is a subclass of NSString.
  •  NSString implements the NameHelper protocol.
  •  NSString has a helper class.

Q9. What’s wrong with this code?

float x = 5.;
  •  Nothing is wrong with this code.✔
  •  Declarations do not need semicolons.
  •  x=5 is an invalid float.
  •  Variables can’t be declared and initialized in the same state.

Q10. How many times with this loop be executed?

for (int x=0; x<100; x++) {
  x = x + 1;
}
Code language: HTML, XML (xml)
  •  50✔
  •  99
  •  100
  •  This code contains an error.

Q11. What is this code an example of?

[self addObserver: self forKeyPath: @"val" options:0 context: nil];Code language: PHP (php)
  •  Key-Value Observing✔
  •  Class Value Observing
  •  Key-Data Observing
  •  KeyPath Observing

Q12. What does ARC stand for?

  •  Automatic Reference Counting✔
  •  Automatic Retain Checking
  •  Async Retain Cycles
  •  Automatic Release Code

Q13. What is printed for this code?

int val = 0;
val = 1.5;
printf("%d", val);
Code language: JavaScript (javascript)
  •  1✔
  •  2
  •  0
  •  This code contains an error.

Q14. What best describes class inheritance in Objective-C?

  •  single inheritance but multiple protocol implementation✔
  •  Objective-C doesn’t support inheritance
  •  dual-class inheritance
  •  unlimited class inheritance and protocol adherence

Q15. How many keys does this NSDictionary have after this code is executed?

NSDictionary *dict = [[NSDictionary alloc] initWithObjectsAndKeys: @"b", @"e", @"a", @"r", nil];Code language: JavaScript (javascript)
  •  2✔
  •  4
  •  5
  •  This code contains an error.

Q16. What is the error in this code?

NSMutableDictionary *dict1 = [NSMutableDictionary dictionaryWithCapacity:5];
[dict1 setValue:@"key" forKey:@"value"];Code language: JavaScript (javascript)
  •  The key and value items are mixed
  •  Nothing is wrong with it✔
  •  You can’t set the capacity of a dictionary
  •  NSMutableDictionary doesn’t have a :setValue:forKey function.

Q17. What is printed from this code?

NSData *data = [@"print" dataUsingEncoding:NSASCIIStringEncoding];
NSLog(@"%@", [[NSString alloc] initWithData:data encoding:NSASCIIStringEncoding]);Code language: JavaScript (javascript)
  •  print✔
  •  This code is invalid
  •  Nothing is printed from this code.
  •  nil

Q18. What is different about this function?

+(void)doSomething;Code language: JavaScript (javascript)
  •  It is static✔
  •  It is abstract.
  •  It is inline.
  •  This code contains an error.

Q19. Structs can have _?

  •  functions
  •  initializers
  •  fields✔
  •  all of these answers

Q20. What is wrong with this code?

@interface MyClass : NSObject
    @property (strong, nonatomic, readonly) NSString *name;
  @endCode language: CSS (css)
  •  There is nothing wrong with this code.✔
  •  There is no read-only directive.
  •  MyClass doesn’t implement NSObject.
  •  Properties are declared in the implementation.

Q21. What is an enums base type for the code below?

typedef enum { Foo1, Foo2} Foo;
  •  There is no base type.✔
  •  NSObject
  •  int
  •  NSNumber

Q22. If you want to store a small amount of information (e.g., user settings), what’s the best, built-in way to go?

  •  UserDefaults✔
  •  plist file
  •  CoreData
  •  TextFile

Q23. What are categories used for?

  •  to extend other classes✔
  •  to manage access control
  •  to coordinate objects
  •  to group classes

Q24. What is this Objective-C code checking?

if ([keyPath isInstanceOf:[NSString class]]) {
}
Code language: CSS (css)
  •  This code contains an error✔
  •  if keyPath is an instance of NSString
  •  if keyPath’s baseclass is the same as NSString’s baseclass
  •  if keyPath implements the same methods as NSString

Q25. What is this a declaration of?

int(^foo)(int);
  •  an Extension
  •  a Generic
  •  a block of code✔
  •  an abstract class
1. _val = 1;
2. self.val= 100;
Code language: PHP (php)
  •  Statement 2, since it calls the auto-created setter on the property.✔
  •  Statement 1, since it uses the property directly.
  •  Statement 2, since it specifies the class instance to use.
  •  Statement 1, since it calls the auto-created setter on the property.

Q27. What is wrong with this code?

float x = 2.0;
int(^foo)(int) = ^(int n1) {
  return (int)(n1*x);
};
foo(5);
Code language: JavaScript (javascript)
  •  Ints and floats can’t be multiplied.
  •  The parameter isn’t declared correctly.
  •  x is not in the right scope.
  •  Nothing is wrong with this code.✔

Q28. What’s the difference between an array and a set?

  •  Arrays are ordered, non-unique values.✔
  •  Arrays are stored sorted.
  •  Sets are ordered, unique values.
  •  Sets can contain nils.

Q29. Dot notation can be used for _?

  •  nothing, as they’re never used in Objective-C
  •  function calls only
  •  property getter/setter✔
  •  parameter delimiters

Q30. What is the value of newVals after this code is executed?

NSArray *vals = @[@"1", @"2", @"3"];
NSPredicate *pred = [NSPredicate predicateWithFormat:@"SELF.intValue > 1"];
NSArray *newVals = [vals filteredArrayUsingPredicate:pred];
Code language: JavaScript (javascript)
  •  2,3✔
  •  nil
  •  This code contains an error
  •  2,”3″

Q31. How would this function be called?

-(int)foo:(int)a b:(int)c;Code language: CSS (css)
  •  self.foo(5, b:10);
  •  This code contains an error.
  •  [self foo:5:10:20];
  •  [self foo:5 b:10];✔

Q32. What is the type of error return value stored in JSON?

NSError *error;
NSData *data;
id json = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingAllowFragments error:&error];
  •  NSString
  •  NSArray
  •  id✔
  •  NSDictionary

Q33. What is significant about this function declaration?

-(void)testFunc:(NSString**)str;Code language: JavaScript (javascript)
  •  The parameter is passed by value and can not be changed
  •  ** is not allowed on a parameter
  •  The parameter may be nil
  •  The parameter is passed by reference and may be changed✔

Q34. What is printed from this code execution?

typedef enum {
    thing1,
    thing2,
    thing3
} Thing;
-(void) enumStuff {
    NSLog(@"%d", thing2);
}Code language: JavaScript (javascript)
  •  0
  •  1✔
  •  thing2
  •  This code does not print anything

Q35. You are worried about threaded access to a property and possible collision in writing. What directive should you use on the property?

  •  non-atomic
  •  strong
  •  weak
  •  atomic✔

Q36. What is wrong with this line of code?

int temp = 1==1;
  •  temp is a keyword.
  •  1==1 is invalid.
  •  1==1 evaluates to a Boolean.
  •  Nothing is wrong with it.✔

Q37. What is special about the code within this block?

dispatch_async(dispatch_get_main_queue(), ^{
// code
});Code language: JavaScript (javascript)
  •  It executes on the main queue.✔
  •  It is the last code to run before the app goes inactive.
  •  It executes on a background thread.
  •  It is queued to execute in the background.

Q38. How many items are in set1 after this code executes?

NSMutableSet *set1 = [NSMutableSet setWithObjects: @1,@2, @3, @4, @5, nil];
[set1 add0bject:@3];
  •  zero
  •  six
  •  one
  •  five✔

Q39. What is wrong with this code?

NSDictionary *d1 = @[@"v1", @4, @"v2", @5.6, @"v3"];
NSlog(@"d1: %@", d1);
Code language: JavaScript (javascript)
  •  NSDictionary cannot be printed this way.
  •  The last key is missing a value.✔
  •  Dictionaries cannot have mixed types as values.
  •  d1 is assigned an NSArray of values.

Q40. What is the initial value of the property val?

@property (nonatomic, readonly) int val;Code language: CSS (css)
  •  8
  •  nil
  •  -1
  •  undefined✔

Q41. Which thread should UI updates be processed on to avoid crashes and application lag?

  •  UI✔
  •  dispatch
  •  background
  •  main

Q42. What is the value of val after this code is executed?

NSString *val = @"1.23";
BOOL tf = val.boolValue;Code language: JavaScript (javascript)
  •  This code is invalid
  •  YES
  •  NO✔
  •  1

Q43. In this code, what does ThatOne refer to?

@interface TestClass : ThisOne <ThatOne>Code language: HTML, XML (xml)
  •  the parent class of TestClass
  •  the name of the category being created for ThisOne
  •  a protocol implemented by ThisOne✔
  •  a helper file’s name

Q44. What is the value of the result after this code is executed?

NSString *result = [Ftest"
    stringByTrimmingCharactersInSet.NSCharacterSet.alphanumericCharacterSet];
  •  “”
  •  “es”
  •  “test”✔
  •  none of these answers

Q45. When will self receive the notification based on this code?

MyClass .classObj = [[MyClass allot] init];
[class0bj add0bserver:self forKeyPath:@"name"
              options:NSKeyValueObservingOptionNew context:NULL];
Code language: PHP (php)
  •  none of these answers
  •  class0bj will receive the notification, not self.
  •  when class0bj is set to “name”
  •  when the name property in the class0bj instance changes✔

Q46. What is wrong with this code?

[*"true" boolValue];Code language: CSS (css)
  •  String literals are not created with*.
  •  NSString doesn’t have a boolValue function.✔
  •  “true” has no meaning.
  •  There is nothing wrong with this code.

Q47. How many times does this loop execute?

int loopVal = 0;
for (int i=0; i>loopVal; i--){
    i--;
}
  •  an infinite number of times
  •  This code is invalid.
  •  zero✔
  •  one

Q48. What will this code print?

NSLog(@"%lu", @"test".length);Code language: JavaScript (javascript)
  •  “test”
  •  Nothing, this code is invalid.
  •  4✔
  •  0

Q49. What is the value of numVtoInt after this code is executed?

NSNumber *numV = [NSNumber numberWithFloat:6.7];
int numVtoInt = numV.intValue;
  •  6
  •  0
  •  6.7
  •  7✔

Q50. What does this code print?

NSString *val = @"1.23";
NSLog(@"%.04f", val.floatValue);
Code language: JavaScript (javascript)
  •  1.2300✔
  •  .04
  •  This code is invalid
  •  1

Q51. What is the maximum possible value of r1 in this code?

int r1 = arc4random() % 10;
  •  0
  •  9✔
  •  1
  •  10

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