Dictionary object (nsdictionary and nsmutabledictionary)-objective-C

Nsdictionary serves the same purpose as the dictionary class in Java and provides a set of "key-value" pairs.

Summary of common nsdictionary Methods

+ (ID) dictionarywithobjectsandkeys: obj1, key1, obj2, key2, ...... Nil	Add objects and key values in sequence to create a dictionary. Note that the end is nil.
-(ID) initwithobjectsandkeys: obj1, key1, obj2, key2, ...... Nil	Initialize a new dictionary, adding objects and values in sequence, ending with nil
-(Unsigned INT) count	Returns the number of records in the dictionary.
-(Nsenumerator *) keynsenumerator	Returns all keys in the dictionary to an nsenumerator object.
-(Nsarray *) keyssortedbyvalueusingselector :( SEL) Selector	Sort all keys in the dictionary by the method specified by selector and return the result.
-(Nsenumerator *) objectenumerator	Returns all values in the dictionary to an nsenumetator type object.
-(ID) objectforkey: Key	Returns the object with the specified key value.

Summary of common nsmutabledictionary Methods

+ (ID) dictionarywithcapacity: Size	Create a variable Dictionary of size
-(ID) initwithcapacity: Size	Initializes a variable Dictionary of size.
-(Void) removeallobjects	Delete all elements in the dictionary
-(Void) removeobjectforkey: Key	Delete the key position element in the dictionary
-(Void) setobject: OBJ forkey: Key	Add (Key, OBJ) to the dictionary. If the key already exists, replace it with obj.