Objective-c Arrays and dictionaries

(1) array

nsarray* array = [[Nsarray alloc] initwithobjects:@ "Hello" @ "World", nil]; Only object types can be stored, and the underlying type, such as int, may be converted to a string type and then passed in

(NSString) [Array objectatindex:1]; Remove the first element and return to the string

Note: Nsarray can not be changed, cannot add delete element

(2) Variable group

nsmutablearray* arr = [[Nsmutablearray alloc] init];

[arr AddObject: @ "Hello"];

[Arr removeobject:@ "Hello"];

[Arr removeobjectatindex:0];

[Arr Removeobject:inrange:]

(3) Dictionary

nsdictionary* dic = [nsdictionary dictionarywithobjectsandkeys:@ "Obj1", @ "Key1", @ "Obj2", @ "Key2", nil];

[DiC objectforkey:@ "Key1"];

Note: Nsdictionary and Nsarray are immutable.

(4) Variable dictionary

nsmutabledictionary* dic = [[Nsmutabledictionary alloc] init];

[DiC setobject:@ "Obj1" forkey:@ "Key1"];

Access is the same as nsdictionary.

Objective-c Arrays and dictionaries