Top 25 Objective C Interview Questions & Answers (2021)
The class used to establish a connection between applications to the web server are
25) What is dot notation?
13) What are the characteristics of the category?
The objective-c program basically consists of
NS object is the parent class and consists of a number of instance variables and instance methods.
60 Interview Questions
Every iOS Developer Should Know. (Part 1)
The rule is to not retain it because it’s already retained elsewhere and more important you’ll avoid retain cycles.
A protocol declares a programmatic interface that any class may choose to implement. Protocols make it possible for two classes distantly related by inheritance to communicate with each other to accomplish a certain goal.
Because no name is given in the parentheses, class extensions are often referred to as anonymous categories. Unlike regular categories, a class extension can add its own properties and instance variables to a class.
The syntax to define a block literal uses the caret symbol (^), like this:
Yes, To provide custom access logic, you will need to write your own getter and setter methods.
Most Frequently Asked Objective C Interview Questions
Here in this article, we will be listing frequently asked Objective C Interview Questions and Answers with the belief that they will be helpful for you to gain higher marks. Also, to let you know that this article has been written under the guidance of industry professionals and covered all the current competencies.
An ANSI-based version of the standard C programming language, Objective-C is the key programming language used for mobile app development by companies that make apps for OS X and iOS. Objective-C is developed on top of C language by adding Small Talk features that make it an object-based language. Is this helpful? Yes No
Objective-C was created by Tom Love and Brad Cox at their company Stepstone in the early 1980s. Is this helpful? Yes No
Apple released Objective-C 2.0 at the Worldwide Developers Conference in 2006. It is its latest version. Is this helpful? Yes No
A protocol announces a programmatic interface that a class chooses to implement. It enables two classes that are related by inheritance to “talk” with each other in order to accomplish a goal. Is this helpful? Yes No
Protocols are of two types – formal and informal. An extension of the Objective-C language, a formal protocol announces a list of methods that client classes are likely to implement.
An informal protocol is one of the categories on NSObject that makes all objects adopters of the protocol. Implementing methods in an informal protocol is optional. Is this helpful? Yes No
#import function ensures a file is included only once so that you do not have a problem with recursive include. import is a super set of include and it ensures file is included once. Is this helpful? Yes No
A category is used to add methods to an existing class. The added methods are usually inherited by subclass and are difficult to differentiate from the original methods at runtime. Categories are used to distribute the implementation of their classes into separate source files.
#import “SystemClass.h” @interface SystemClass (CategoryName) // method declarations @end Is this helpful? Yes No
NSMutableArray is the subclass of NSArray and they both manage collections of objects known as arrays. NSArray is responsible for creating static arrays, whereas NSMutableArray is responsible for creating dynamic arrays. Is this helpful? Yes No
The object is a collection of as an array or set of Cocoa classes that may include the collection classes. This collection of classes adopts the NSFastEnumeration protocol. This protocol can be used to retrieve elements that are held by an instance by using a syntax that is similar to a standard C for loop.
Look at this instance: NSArray *anArray = // get an array; for (id element in anArray) { /* code that acts on the element */ } Is this helpful? Yes No
@synthesize creates getter and setter for the variables and allows you to specify attributes for variables. When you @synthesize the property to the variable, you generate getter and setter for that variable. Is this helpful? Yes No
This is how you call a function: [className methodName] For announcing methods in same class, use this: [self methodName] Is this helpful? Yes No
The dot syntax is a shortcut for calling getter and setter.
You can use this: [foo length] foo.length are exactly the same, as are: [foo setLength:5] foo.length = 5 Is this helpful? Yes No
NSObject is the root class from which a lot of other classes inherit. When an object encounters another object, it interacts using the basic behavior defined by the NSObject description. Is this helpful? Yes No
Atomic is the default behavior that ensures the present process is completed by the CPU.
Non-Atomic is not the default behavior and may result in unexpected behavior. Is this helpful? Yes No
GCD refers to GrandcentralDispatch. GCD creates only one thread for executing the blocks and those blocks execute sequentially. The best thing about GCD is that the programmer does not have to create threads or match the number of threads to the available processors. Is this helpful? Yes No
KVC stands for Key-Value-Coding. It refers to accessing a property or value using a string. id someValue = [myObject valueForKeyPath:@”foo.bar.baz”]; Which could be the same as: id someValue = [[[myObject foo] bar] baz];
KOC stands for Key-Value-Observing. It allows programmers to observe changes in property or value. In order to observe a property using KVO, you should identify the property with a string. The observable object must be KVC compliant. [myObject addObserver:self forKeyPath:@”foo.bar.baz” options:0 context:NULL]; Is this helpful? Yes No
You can dealloc for memory management. Once an object “retainCount” reaches 0, a dealloc message is sent to that object. Never call dealloc on objects unless you call [super dealloc]; around the close of a overridden dealloc. (void)dealloc { [ivar release]; //Release any retained variables before super dealloc [super dealloc]; //Only place in your code you should ever call dealloc } Is this helpful? Yes No
Blocks are language-level features that are added to Objective C, C, and C++. Blocks allow you to create segments of code that can be passed to methods or functions as values. Syntax to define a block uses the caret symbol (^): ^{ NSLog(@”This is a block”); } Is this helpful? Yes No
Responder chain is a series of responder objects that are linked together. A chain starts with the first responder and ends with the app object. However, when the first responder is unable to handle an event, it forwards it to the next responder in the chain. Is this helpful? Yes No
Is this helpful? Yes No
It is a pointer to any type, but unlike a void *, it points to an object. For instance, you add anything of type id to an NSArray as long as those objects are responding to retain and release it. Is this helpful? Yes No
@interface A: NSObject; @end @interface B : A @end
Here, the init method is inherited from A to B. However, the method has a different return type in both classes. Is this helpful? Yes No
No. Objective-C does not support overloading, so you will need to use a different method. Is this helpful? Yes No
It is an object that acts in coordination with, on behalf of, other objects when those objects encounter an event in a program.
If you want to retain a delegate, it can be retained. However, the rule is not to retain it because it must e already retained you will avoid unnecessary retain cycles. Is this helpful? Yes No
Because it is a synchronous process. The idea of dispatch_once() is to perform a task only once, no matter how violent the threading becomes. Is this helpful? Yes No
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What is Objective C ?
In the present competitive and advance job market, managers are taking a gander at a few perspectives beyond their qualification. You should be sufficiently equipped to secure your specific job position. Answering the important questions accurately in the job interview is as imperative as displaying your confidence level, stress dealing capacity and your positive approach towards any situation.
Objective C is a computer language that guides in protest arranged programming. While choosing a possibility to deal with this programming language, a few objective C questions are inquired. The essential questions for a fresher in the field vary from that of an experienced candidate. A fresher is asked simple and basic questions related to objective C. Interviewers can also ask the questions related to the topic object-oriented programming, while an experienced competitor should answer advanced level inquiries with coding cases and graphs.
Along these lines, the most vital step you have to take before you go for the interview is to catch up on your nuts and bolts. You should ponder about the critical questions that can come up to you in the objective C interview. All things considered, you require not to stress as we are there to take care of your concern. Given below is a portion of the regular questions (with answers) that an interviewer can ask in any job interview. Read through them, endeavor to make sense of the most suitable answer and be set up to confront the interview confidently.
Below are the list of Best Objective C Interview Questions and Answers
An abstraction in OOP is the way toward lessening the undesirable data and keeping up just the relevant data for the clients while polymorphism empowers an object to execute their functions in at least two forms.
@synthesize: It creates getter and setter techniques for your property.
@dynamic: We utilize dynamic for subclasses of NSManagedObject. @dynamic tells the compiler that getter and setters are executed elsewhere.
Once you have just pronounced the property in Objective-C, you need to tell the compiler in a split instantly by utilizing synthesize directive. This will advise the compiler to create a getter&setter message.
Cocoa applications are fundamentally created utilizing Objective C dialect. It is based out of ANSI C consequently ANSI C code can be blended with Objective C code while building up a Cocoa Application.
