NSNumber: Can instantiate object that CONTAINS integers, floats or doubles.

NSDate: For storing streams of bytes, writing data objects to the file system and reading from them.

NSDate: Displaying dates, times in many formats. Time adjustments based on time ZONES.

NSString: DIFFERENT representation of character strings such as UTF-8 etc.

NSAttributedString: Supports strings with attributes such as font etc.

NSArray: Ordered collection of objects, uses zero based indexing.

NSDictionary: Managing key value pairs, Dictionaries are unordered and must contain unique keys.

NSSet: Similar to NSArray but unsorted. Contains distinct objects.

NSFileManager: Used for file operations.

NSThread: Used for creating multithreaded programs.

NSOperation & NSOperationQueue : To PERFORM MULTIPLE operations (concurrent & Non-Concurrent) in priority and dependence order.

NSXMLParser: To process XML Data.

NSXML: Used to represent a XML document as a hierarchical tree.

NSNumber: Can instantiate object that contains integers, floats or doubles.

NSDate: For storing streams of bytes, writing data objects to the file system and reading from them.

NSDate: Displaying dates, times in many formats. Time adjustments based on time zones.

NSString: Different representation of character strings such as UTF-8 etc.

NSAttributedString: Supports strings with attributes such as font etc.

NSArray: Ordered collection of objects, uses zero based indexing.

NSDictionary: Managing key value pairs, Dictionaries are unordered and must contain unique keys.

NSSet: Similar to NSArray but unsorted. Contains distinct objects.

NSFileManager: Used for file operations.

NSThread: Used for creating multithreaded programs.

NSOperation & NSOperationQueue : To perform multiple operations (concurrent & Non-Concurrent) in priority and dependence order.

NSXMLParser: To process XML Data.

NSXML: Used to represent a XML document as a hierarchical tree.