iOS Collection Summary

Nsarray for an ordered set of objects (equivalent to an array)

Nsset for object unordered collection

nsdictionary for key-value mappings the above three collection classes are immutable (once initialized, you can no longer dynamically add or remove elements), and if you need to use a mutable collection, you need to use the following classes:

Nsmutablearray

Nsmutableset

Nsmutabledictionary

Example Demo:

1:nsarray Initialization and traversal iterations

（1Nsarray initialization function of Nsarray:-(ID) Initwithobjects: (ID) Firstobject, ....; Nsarray's handy constructor:+(ID) Arraywithobjects: (ID) Firstobject, ...; Demo://convenient initialization of the NsarrayNsarray*array1 = [[Nsarray alloc] Initwithobjects:@"AAA",@"BBB",@"CCC", nil]; //Nsarray's Handy builderNsarray*array2 = [Nsarray arraywithobjects:@"111",@"222",@"333", nil]; (2gets the number of array elements and arrays of elements//get the number and elements of an array element           intCount = (int) [array1 Count]; //gets the element of the corresponding index          IDelement = [Array1 Objectatindex:0]; NSLog (@"Array1_count =%d, array[0] =%@", count, Element); (3) Iteration://encapsulates a function that iterates through an array      voidArray_display (IDArray) {        for(inti =0; i < [array count]; i++) {          IDtemp =[Array objectatindex:i]; NSLog (@"%@", temp); }    }

View Code

2:nsmutablearray Initialization and traversal iterations

 2. Variable array: The capacity of the Nsmutablearray Nsarray is fixed, and the capacity of Nsmutablearray is variable, we can initialize a capacity when the Nsmutablearray is instantiated, but this capacity is not fixed, When it's not enough, it automatically increases. Nsmutablearray is a subclass of Nsarray, an extension of nsarray. (1Nsmutablearray initialization function of Nsmutablearray:-(ID) Initwithcapacity: (Nsuinteger) NumItems; Nsmutablearray's handy constructor:+(ID) Arraywithcapacity: (Nsuinteger) NumItems; Demo://convenient initialization of the NsmutablearrayNsmutablearray *array3 = [[Nsmutablearray alloc] Initwithcapacity:3]; //Nsmutablearray's Handy builderNsmutablearray *array4 = [Nsmutablearray arraywithcapacity:3]; (2elements added and removed add elements:-(void) AddObject: (ID) AnObject; --add elements to the end of the array to delete the entire contents:-(void) removeallobjects; Delete the last element:-(void) Removelastobject; To delete an element by index:-(void) Removeobjectatindex: (Nsuinteger) index; Delete any one of the elements:-(void) Removeobject: (ID)Object; Demo://Initialize NsmutablearrayNsmutablearray *array = [Nsmutablearray arraywithobjects:@"111",@"222",@"333", nil];//adding elements[Array AddObject:@"444"]; //remove Element[Array Removeobject:@"111"]; //remove the last element[Array removelastobject];//Delete an element by index[Array Removeobjectatindex:0];  Array_display (array); Delete any one of the elements:-(void) Removeobject: (ID)Object;//Initialize NsmutablearrayNsmutablearray *array = [Nsmutablearray arraywithobjects:@"111",@"222",@"333", nil];//adding elements[Array AddObject:@"444"]; //remove Element[Array Removeobject:@"111"]; //remove the last element[Array removelastobject];//Delete an element by index[Array Removeobjectatindex:0]; Array_display (array);

View Code

iOS Collection Summary