Objective-C Interview Questions and Answers

Objective-C Interview Questions and Answers

Objective-C is an object-oriented, general-purpose programming language that adds Smalltalk-style messaging to the C programming language. It was the main programming language used by Apple for the OS X and iOS operating systems, and their respective application programming interfaces (APIs) Cocoa and Cocoa Touch prior to the introduction of Swift. Objective-C is a fundamentally simple language. Its syntax is small, unambiguous, and easy to learn. Object-oriented programming, with its self-conscious terminology and emphasis on abstract design, often presents a steep learning curve to new recruits. A well-organized language like Objective-C can make becoming a proficient object-oriented programmer that much less difficult.

Objective-C supports an open style of dynamic binding, a style that can accommodate a simple architecture for interactive user interfaces. Messages are not necessarily constrained by either the class of the receiver or even the method name, so a software framework can allow for user choices at runtime and permit developers freedom of expression in their design. (Terminology such as dynamic binding, message, class, and receiver are explained in due course in this document.)

The programming language Objective-C was originally developed in the early 1980s. It was selected as the main language used by NeXT for its Next STEP operating system, from which OS X and iOS are derived. Portable Objective-C programs that do not use the Cocoa or Cocoa Touch libraries, or those using parts that may be ported or re implemented for other systems, can also be compiled for any system supported by GNU Compiler Collection (GCC) or Clang.

What is Object C?

What is id in Objective C?

Explain Cocoa/Cocoa Touch?

How do I make a static method in Objective –C?

How can I link a C++ library into an Objective-C program?

What is OOP?

Explain how is objective C and OOP related?

Where is this language most commonly used and by whom?

What is a protocol?

How do I allocate an object on the stack?

What is the difference between interface in Java and protocol on objective C?

What is App Bundle?

What is inheritance in Objective-C?

What do you mean by keyword atomic in Objective C?

How to call the function in Objective-C?

What are objective- C blocks?

What is the difference between mutable and immutable types in Objective C?

What is an IMP in Objective –C?

What is the difference between abstraction and polymorphism?

Name the framework that is used to construct application’s user interface for iOS?

What do you understand by push notification in Objective C?

Explain assign, weak, retain and copy in Objective C?

How do I get an IMP given a SEL in Objective –C?

What is difference between shallow copy and deep copy?

How do I include X Intrinsics headers into an Objective-C file?

Explain when you send autorelease or retain message to autorelease pool?

What's the class of a constant string?

What happens when you invoke a method on a nil pointer?

If I call perform Selector: with Object: after Delay: is the object retained?

How messaging works in Objective-C?