A Brief Introduction to Object-c sets

A Brief Introduction to Object-c sets
A Brief Introduction to Object-c sets


1. Brief Introduction


NSArray/NSMutableArray
NSSet/NSMutableSet
NSDictionary/NSMutableDictionary


NSArray, NSSet, and NSDictionary are immutable and initialized during creation.


NSMutableArray, NSMutableSet, and NSMutableDictionary are variable.


II. Introduction


NSArray is an ordered array.


NSMutableArray * myArray = [[NSMutableArray alloc] init];
// Add Element
[MyArray addObject: @ "good"];
// Delete an element
[MyArray removeObject: @ "good"];
// Quick access
MyArray [index];




NSSet is unordered and can be randomly set. The value can be a dice operation.
NSSet * s = [NSSet setWithObjects: @ "1", @ "2", @ "3", @ "4", @ "5", @ "6"];
NSString * str = [s anyObject];






NSDictionary is an unordered key-value pair. The key value cannot be repeated, and the value can be repeated.


NSMutableDictionary * dict =@{@ "name": @ "lili "};
[Dict setObject: @ "rose" forKey: @ "name"]; // when the second value is assigned, the previous value will be overwritten.
// Add a key-Value Pair
[Dict setObject: @ "Beijing" forKey: @ "address"];
// Remove a key-Value Pair
// [Dict removeObjectForKey: @ "name"];
// Quick access
Dict [@ "name"];


Iii. Similarities


Only OC objects can be stored.