1.What you mean by auto layout in Objective C?
Auto Layout is a new way to define dynamic GUIs. Before we had autoresizing masks, that described how a subview will resize or move when it’s superview is resized.
With Auto Layout you can do the same and also a lot more complicated GUIs quite easily.
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2. Garbage collector in iPhone?
iOS 5.0 has got the ARC ( Automated reference counting ).
Objective C does not have a garbage collector rather it uses the reference counting algorithm to manage the memory.
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3.What is polymorphism?
This is very famous question and every interviewer asks this. Few people say polymorphism means multiple forms and they start giving example of draw function which is right to some extent but interviewer is looking for more detailed answer.
Ability of base class pointer to call function from derived class at runtime is called polymorphism.
For example, there is superclass human and there are two subclasses software engineer and hardware engineer.
Now superclass human can hold reference to any of subclass because software engineer is kind of human. Suppose there is speak function in super class and every subclass has also speak function.
So at runtime, superclass reference is pointing to whatever subclass, speak function will be called of that class. I hope I am able to make you understand.
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4. How is the app delegate is declared by Xcode project templates?
App delegate is declared as a subclass of UIResponder by Xcode project templates.
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5.What is @dynamic and any place where it is used ?
It tells compiler that getter and setter are not implemented by the class but by some other class.May be super class or child class.
Example – Core Data.
The Managed object classes have properties defined by using @dynamic.
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