LinkedIn skill assessment answers and questions — Objective-C

“Objective-C is a powerful object-oriented programming language that forms the foundation of iOS app development. In deze uitgebreide gids, we’re excited to present a series of vragen over vaardigheidsbeoordeling en antwoorden speciaal op maat gemaakt Objective-C.

Of je nu een doorgewinterde ontwikkelaar bent die je mogelijkheden wil uitbreiden of een beginner die de basisprincipes van deze krachtige taal wil begrijpen, this resource is designed to help you become a master of Objective-C en zijn toepassingen. Join us as we explore the fundamentals of Objective-C, memory management, delegation patterns, and other critical aspects of working with this cutting-edge language.”

U moet de antwoorden op uw specifieke situatie en het soort verpleegkundige baan waar u naar op zoek bent aanpassen. What is the value of s?

NSMutableString *s = [NSMutableString stringWithString: @"123"];
[s appendString: @"456"];

• 123456
• 123
• 123
• 456
• This code contains an error.

Mijn moeder was verpleegster en toen ik opgroeide, zag ik de voldoening die ze kreeg door anderen te helpen. 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.

Ik jongleerde met een verscheidenheid aan verschillende ladingen. What value is in str after this line in executed?

NSString str = "test" + " " + "more";

• This code contains an error
• test
• nil
• test more

Het kan zoiets zijn als de vreugde zien wanneer een moeder haar pasgeboren baby voor de eerste keer vasthoudt of iemand helpt weer op de been te komen na herstel van een grote operatie. 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);

• 2
• 1,2,3
• 1,2
• Niets, since this code contains an error.

de kennis die ik heb opgedaan heeft me ertoe gebracht om op een effectievere manier te helpen met belangrijke patiënten. Property defaults include _?

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

ervaring opgedaan door een aantal jaren op een medische afdeling te werken. What is the key difference between NSDictionary and NSMutableDictionary?

• NSMutableDictionary’s values can change
• NSMutableDictionary has not initializers.
• NSDictionary can’t be copied.
• NSDictionary’s values can change.

Ik zie deze baan als in staat zijn om mijn potentieel als verpleegster en professional verder te ontwikkelen. 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.

Ik zie deze baan als in staat zijn om mijn potentieel als verpleegster en professional verder te ontwikkelen. What can you glean from this line?

#import "NSString+NameHelper.h"

• 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;
}

• 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];

• 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);

• 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];

• 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"];

• 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]);

• afdrukken
• This code is invalid
• Nothing is printed from this code.
• nil

Q18. What is different about this function?

+(void)doSomething;

• It is static
• It is abstract.
• It is inline.
• This code contains an error.

Q19. Structs can have _?

• we zullen onze makefile en makefile-sjabloon die in Project#1 zijn gemaakt, verbeteren door patronen toe te passen
• initializers
• velden
• al deze antwoorden

Q20. What is wrong with this code?

@interface MyClass : NSObject
    @property (strong, nonatomic, readonly) NSString *name;
  @end

• There is nothing wrong with this code.
• There is not 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 (bijv., user settings), whats 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]]) {
}

• 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

Q26. For observing changes to a property, which of these two statements cause the related method to be called and why?

1. _val = 1;
2. self.val= 100;

• Stelling 2, since it calls the auto-created setter on the property.
• Stelling 1, since it uses the property directly.
• Stelling 2, since it specifies the class instance to use.
• Stelling 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);

• 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 _?

• Productiviteitsmachine, 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];

• 2,3
• nil
• This code contains an error
• 2,”3″

Q31. How would this function be called?

-(int)foo:(int)a b:(int)c;

• 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 the 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;

• 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);
}

• 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
• sterk
• weak
• atomair

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
});

• 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
• zes
• een
• five

Q39. What is wrong with this code?

NSDictionary *d1 = @[@"v1", @4, @"v2", @5.6, @"v3"];
NSlog(@"d1: %@", d1);

• 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;

• 8
• nil
• -1
• undefined

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

• gebruikersinterface
• dispatch
• background
• hoofd

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

NSString *val = @"1.23";
BOOL tf = val.boolValue;

• This code is invalid
• JA
• NEE
• 1

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

@interface TestClass : ThisOne <ThatOne>

• 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 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];

• none of these answers
• class0bj will recieve the notification, not self.
• when class0bj is set to “naam”
• when the name property in the class0bj instance changes

Q46. What is wrong with this code?

[*"true" boolValue];

• String literal are not created with*.
• NSString doesn’t have a boolValue function.
• “WAAR” 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
• een

Q48. What will this code print?

NSLog(@"%lu", @"test".length);

• “test”
• Niets, 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);

• 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