iOS development OC (18)--foundation (3) Nsarray and Nsmutablearray

Nsarray : Non-variable group

Nsmutablearray: variable Array

C-language arrays: storing basic data types

OC array: Can only hold OC objects, cannot hold non-OC object types, such as int, struct, enum, etc.

1. Creation of immutable variable groups

voidCreate () {/*int a = 5;         int ages[10] = {1, 90, 89, 17};       C-array person *p = [[Person alloc] init];     OC Array (below) person *persons[5] = {p, [[Person alloc] init]}; */        //OC Array cannot hold nil value//OC Arrays can only hold OC objects, cannot hold non-OC object types, such as int, struct, enum, etc.//This array is always an empty array//Nsarray *array = [Nsarray array];            /*creation of 1.NSArray*/Nsarray*array2 = [Nsarray arraywithobject:@"Jack"]; //Nil is the tag at the end of the array elementNsarray *array3 = [Nsarray arraywithobjects:@"Jack",@"Rose", nil]; //[array2 Count]; //Nsarray *array4 = [Nsarray arraywithobjects:@ "Jack", @ "Rose", @ "4324324", nil]; //quickly create a Nsarray object (this method is used only to create immutable groups)Nsarray *array4 = @[@"Jack",@"Rose",@"4324324"]; /*number of elements in 2.NSArray*/NSLog (@"%ld", Array3.count); /*access to elements in 3.NSArray*/NSLog (@"%@", [Array3 Objectatindex:1]); //array3[1];NSLog (@"%@", array3[0]);}

2. Non-variable group traversal

//iterating through an arrayvoiduse1 () { person*p =[[Person alloc] init]; Nsarray*array = @[p,@"Rose",@"Jack"]; //Method 1 (by subscript)//for (int i = 0; i<array.count; i++)//    {    //NSLog (@ "%@", Array[i]); //    }     // Method 2 (for in structure) --Recommended use //ID obj represents each element in an array//int i = 0; //For (ID obj in array)//    {        //        //find the position of the obj element in the array//Nsuinteger i = [array indexofobject:obj]; //    //NSLog (@ "%ld-%@", I, obj); //        //i++; //    //if (i==1)//        {    //Break ; //        }    //    }    // Method 3:block --Recommended use //each time you traverse to an element, the block is called//and the current element and index position are passed as parameters to block[Array Enumerateobjectsusingblock:^(IDobj, Nsuinteger idx, BOOL *stop) {NSLog (@"%ld-%@", idx, obj); if(idx = =0)         {             //Stop Traversal*stop =YES;    }              }]; //the nature of the block above//void ^ (Myblock) (ID, Nsuinteger, bool *) = ^ (Id obj, Nsuinteger idx, BOOL *stop)//    {    //NSLog (@ "%ld-%@", idx, obj); //    //    //if (idx = = 0)//        {    //            //Stop Traversal//*stop = YES; //        }    //    }; //    //for (int i = 0; i<array.count; i++)//    {    //        //used to mark whether or not to stop traversal//BOOL isstop = NO; //    //        //remove Element//id obj = array[i]; //            //Myblock (obj, I, &isstop); //            //            //if (isstop)//        {    //Break ; //        }    //    }}

3. Use of non-variable groups

voidUse2 () {Nsmutablearray*array = [Nsmutablearray arraywithobjects:@"Rose",@"Jim", nil]; //adding elements[Array Addobject:[[person alloc] init]; [Array AddObject:@"Jack"]; //Delete Element//[Array removeallobjects]; //deletes the specified object//[Array removeobject:@ "Jack"];[Array Removeobjectatindex:0]; //wrong wording//[Array Addobject:nil];NSLog (@"%@", array); NSLog (@"%ld", Array.count);}

4. Variable array

Nsmutablearray its use of basic and non-variable groups similar----specific reference to the document, there are many methods, the document description is kingly.

Attention:

int Main () {    //  @[] creates only immutable group Nsarray/    *  error    Nsmutablearray *array = @ [@ "Jack" @ "Rose"];        [Array addobject:@ "Jim"];   */            // Nsarray *array = @[@ "Jack" @ "Rose"];        return 0 ;}

iOS development OC (18)--foundation (3) Nsarray and Nsmutablearray