Practice Question: What is a pointer?

A memory address that points to a specific object


What is the type of @selector(foo)?



What is the difference between [Foo new] and [[Foo alloc] init]?

None, they perform the same actions.


Assume ARC is enabled… What would be another way to write this: NSArray *array = [NSArray arrayWithObjects:@”One”, ©”Two”, @”Threen,nil];

NSArray ‘array = ©[©”One”, ©”Two”, ©”Three”];


Name the core interface framework which is used in iOS development.



what does this code produce? [NSString] *myString = @”Hello World”;

An Error during compile


What framework is KVO (key value observing) a part of?



What is the difference between #import and #include ?

#import ensures that a file is only ever included once, and #include allows the same file to be inlcuded many times.


Are integers full-fledged objects in Objective-C?

No, they are not objects at all.


Yes, but only if you first cast them as id’s, e.g. (id) 123.



True or False? A method and a variable can have the same name in Objective-C.



What is one source of particles that are emitted by a CAEmitterLayer object?

A CAEmitterCell


True or False? For an object to use constraints, it must have at least 3 constraint values.



In Core Data, what is the name of an object representation of a record?



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



What class will allow you to use one or more blocks concurrently?



What is Objective-C’s language design based on?

C and Smalltalk.


What happens at runtime with the following: NSObject* object = nil; NSObject* object2 = [object copy]; NSLog(@”%@,,I object2);

Log prints “(null)” and continues as usual.


What is a proper format for calling an asynchronous function?

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND 0), A{ // code });


The proper typedef syntax for an Objective-C block that takes an NSArray and returns an NSString is

typedef NSString *(AaBlock)(NSArray *);


What is the ‘print object’ command in the debugger window?

Answer: po


What can happen if you use self inside a block?

You can create a retain cycle


If you do not declare a return type for a method definition, what is the default return type?

Answer: id


What is the object.toString equivalent is objective-c?

[NSObject description]


How do you convert a Core Image color to a UlColor?



What is (void*)0 ?

Representation of NULL pointer


Using UlViewController containment, which one of the following statements is true:

The root viewcontroller handles loading and unloading its child viewcontrollers.


What are the two types of predicates?

Comparison and Compound


What does the following code do, assume ARC is enabled? NSArray *myArray; for (int i = 0; i < 10; i++X @autoreleasepool { myArray = [[NSArray alloc]init]; }}

For each iteration of the loop a new array is allocated and released.


Which of these classes is NOT a root class?



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



True or False? Strings are one of the most common sources of buffer overflow attacks.



True or False? You can use %@ to specify a dynamic property.



What can you say about the code: NSString * str = [NSString stringWithFormat:@””]; [str release];

It will cause the string to be released twice with undefined consequences when the surrounding autorelease pool is emptied


Which of these property declaration attributes does not specify setter semantics?



If you wanted to override the default alloc method in a class Foo, what would be the appropriate way to declare it?

+ (id) alloc;


True or False? You can perform operator overloading in Objective-C.



What protocol is used to create an action object?



True or False? You should use NSHost when connecting to a specific host.

False (You should use CFHost)


Objective-C methods with certain names (“init”, “alloc”, etc.) always return objects that are an instance of the receiving class’s type; such methods are said to have a “related result type”. A method with a related result type can be declared by using:



What class method is used to make an NSArray from NSData class?

NSKeyedUnarchiver unarchiveObjectWithData:


True or False? The format for a NSPredicate is the same as a Regular Expression.



How do you add a brightening effect on a Corelmage?



Which method, if defined, is guaranteed to be called once — and only once — when a class is first referenced?

+ (void) initialize;


What do you use for an outgoing TCP connection?



What is the last chance for an object to handle a message?

-forward Invocation:


What is the export format for the Carbon Events Instrument?

A DTrace Script


What kind of socket does a CFSocket use?

A BSD Socket


True or False? Key value coding is used to indirectly access an object’s attributes using indexes.



How can you declare a method, that can be set as the action to be performed on various events?

– (IBAction) action:(id) sender;


True or False? Sending a command asynchronously will lock the main thread and then wait until the command is finished before moving on to the next part of your code.



Does Objective-C have constructors and destructors?

No, you use init and dealloc on Objective-C


What is used to sort Core Data results?



If a class conforms to a protocol what must it do?

Implement all methods in the protocol, except for optional ones


What is a Category?

A category is a way to extend a class by adding functions to it


Can you call C++ code from objective C environment?

Yes, from any .mm file


How can you add a new method too to an existing class Bar?

Make a category, e.g. @interface Bar(Foo).


Which of these methods is NOT invoked by the runtime itself?



What is a dependency in NSOperationQueue?

A dependency is a way to have an operation wait to be performed until the dependencies have been fulfilled/executed


Which of the following accesses a variable in structure b?



What is the Allocations instrument used for?

Recording information from a single process about memory allocation


How does KVO respond to change notifications?



True or False? You can compare two strings by (string1 == string2)



How is a selector typically represented in memory?

As a null terminated C string.


What is KVO?

Key Value Observing


How do you get the Unicode character set of a Core Text font?



Storyboards were introduced with which version of iOS?

Answer: 5.0


True or False? A UIButton inherits from UlView.



What is the function that determines what is in the cells of a tableView?



What type of object is this under XCode 4.5: @[rabbit, chicken, owl]



What is the difference between methods that begin with + and -?

Instance methods begin with – class level methods begin with +


What is the method for adding KVO to your app?



What happens when you call retain on an object?

You increase its retain count by 1


Which of the following is a Singleton?

[NSFileManager defaultManager]


What does the “id” type mean?

This is the general type for any kind of object regardless of class


What does a CAEmitterCell do?

It defines the properties and direction of emitted particles from a CAEmitterLayer object.


How do you concatenate two NSStrings *foo and NSString *bar to form a new NSString *baz?

baz = [foo stringByAppendingString: bar];


What framework does the class UIButton come from?



What does an Objective-C string literal look like?



If you define a new class called Foo which inherits from NSObject, how do you create a new instance of it?

Foo *temp = [[Foo alloc] init];


Where is a MKAnnotationView used?

On a Map View


ARC means?

Automatic Reference Counting


What is a delegate?

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


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



Objective C is the main programming language for which platform?

Answer: iOS

Objective-C Test Questions and Answers

Добавить комментарий

Ваш e-mail не будет опубликован. Обязательные поля помечены *

Этот сайт использует Akismet для борьбы со спамом. Узнайте как обрабатываются ваши данные комментариев.