Objective-c Learning Arrays

Overview:

1. The array inside OC is a linear structured data type, within the foundation framework. Divided into mutable arrays (Nsarray) and non-variable groups (Nsmultiarray), where MultiArray inherits from Nsarray, so Nsarray's various methods, Nsmultiarray as can be used.
2. The array can be indexed to the corresponding object by subscript.
3. The content stored in Nsarray and Nsmultiarray can only be-objects (instances of classes). So the basic data types cannot be stored directly, and can be stored in Nsvalue or NSNumber packages.

Array Data Model:

1. The array inside OC is a linear data structure whose data prototype is a linear table. Abstract data types for linear tables (definition + operations) are shown
2. There are 8 kinds of operations: about: Adding or deleting the number of changes to find empty
3. 
   

Common Operations for arrays

an array in iOS is an image implementation of this abstract data structure of linear tables, and here's how Apple's handlers implement this linear structure.

1 Initialization: (Initialize operation, set up an array object, and assign value)

1 class Method initialization: (note here Apple's naming specification, class method is generally classwith, the naming specification is actually very important), here are four kinds of cases: an object, multiple objects, using an array, from the file initialization

        class method naming specification        //initializing one  because it is immutable so practicality is not strong        nsarray *arr1=[nsarray arraywithobject:@ "Hello"];                Multiple ends with nil as an array        nsarray *arr2=[nsarray arraywithobjects:@ "1", @ "2", nil];        The element points to the same position        Nsarray *arr3=[nsarray ARRAYWITHARRAY:ARR2];        Initialize an array from a file//        Nsarray *arr3=[nsarray arraywithcontentsofurl:<# (Nsurl *) #>];

2 Instance method initialization:

Nsarray *arr4=[[nsarray alloc] initwitharray:arr1];

3 initialization of a mutable array

        Added an empty array        nsmutablearray *mularray1=[nsmutablearray array];        Initialize, plus capacity        nsmutablearray *mularray=[nsmutablearray arraywithcapacity:1];

2 Array Length: (Returns the number of array elements)

        Number of elements        int count=[arr2 count];

3 Check: Returns the array I object,

        which element is accessed        nsstring *string1=[arr1 objectatindex:0];

        Finds the last object        NSLog (@ "%@", [arr2 Lastobject]);

Traverse

        Fast traversal for        (/* or id*/nsstring *string in Mularray)        {                    }

4: Finds an array based on an object, returns an ordinal if the same object exists, otherwise returns false

Query object position        int objindex=[arr2 indexofobject:@ "2"];

        Judging if there is this element  this is to judge if there is no        if (![ ARR2 containsobject:@ "a"])           {               NSLog (@ "no");           }

5 Increase: add element at position I

        Append the object, return the new array        nsarray *arr11=[arr1 arraybyaddingobject:@ "haha"];

immutable groups cannot be modified by arrays, and operations here are mutable.

        Add object for        (int i=0;i<20;i++)        {            [mularray addobject:@ "AAA"];            [Mularray addobject:@ "BBB"];        }        Add an element based on the index location        [Mularray insertobject:@ "BBB" atindex:1];

6 Delete: Remove the specified position element

        Delete        //delete last        [Mularray removelastobject];        Delete the corresponding element        [Mularray removeobject:@ "AAA"];        Specify the coordinates to delete        [Mularray removeobjectatindex:3];                Delete        [Mularray removeobjectsinarray:arr1] According to the array;

7 Change: Modify the specified position element (that is, replace)

        Replace        [Mularray replaceobjectatindex:0 withobject:@ "1"];

8 null: Empty, return true false

there is no array empty operation in iOS, you can use count==0 to judge

Welcome reprint, Reprint please indicate source: http://blog.csdn.net/zhenggaoxing/article/details/43559869This series of posts directory:OBJECTIVE-C Learning Series Catalog Update not timed

Objective-c Learning Arrays