iOS Developer Interview Preparation Guide

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Cocoa is for Mac App development and cocoa touch is for apples touch devices - that provide all development environment

In non atomic no such guaranty that value is returned from variable is same that setter sets. at same time

☛ private - limits the scope class variable to the class that declares it.
☛ protected - Limits instance variable scope to declaring and inheriting classes.
☛ public - Removes restrictions on the scope of instance variables

to get the any update /alert from server .

A category allows you to add methods to an existing class—even to one for which you do not have the source.

*strong -o "own" the object you are referencing with this property/variable. The compiler will take care that any object that you assign to this property will not be destroyed as long as you (or any other object) points to it with a strong reference.

An operation object is a single-shot object—that is, it executes its task once and cannot be used to execute it again. You typically execute operations by adding them to an operation queue An NSOperationQueue object is a queue that handles objects of the NSOperation class type. An NSOperation object, simply phrased, represents a single task, including both the data and the code related to the task. The NSOperationQueue handles and manages the execution of all the NSOperation objects (the tasks) that have been added to it.

In synchronous request main thread gets block and control will not get back to user till that request gets execute.
In Asynchronous control gets back to user even if request is getting execute.

release - destroy the object from memory,
autorelease - destroy the object from memory in future when it is not in use.

Garbage Collection is a Memory Management feature. It manages the allocation and release of the memory to your applications. When the garbage collector performs a collection, it checks for objects in the managed heap that are not executed by the applications.