Array in Objective-c

Arrays are ordered, can only hold objects, arrays have the concept of subscript (index), index elements by index, subscript starting from 0, the array is divided into non-variable groups (Nsarray) and variable arrays (Nsmutablearray).

Immutable variables Group (nsarray)

Creating an Array Object

1 // create array object
2 NSArray * arr1 = [NSArray arrayWithObjects: @ "a", @ "Apple", @ "c", nil];
3 NSLog (@ "arr1:% @", arr1);
Number of array elements

// number of elements
NSLog (@ "arr1:% lu", arr1.count);
Array element access

1 // array access
2 NSLog (@ "object:% @", [arr1 objectAtIndex: 1]);
Iterating through an array

1 // traverse the array
2 for (NSInteger i = 0; i <arr1.count; i ++) {
3 NSLog (@ "% @", [arr1 objectAtIndex: i]);
4}
Variable array (NSMultableArray)

Create array

1 // Usually create an empty container to store data objects
2 NSMutableArray * mArr = [NSMutableArray array];
3 // add element added at the end of the array
4 [mArr addObject: @ "lol"];
Insert element

1 // Insert an element according to the subscript position
2 [mArr insertObject: @ "a" atIndex: 0];
3 NSLog (@ "% @", mArr);
Delete element

1 // delete
2 [mArr removeObjectAtIndex: 0];
3 [mArr addObject: @ "abc"];
4 [mArr addObject: @ "123"];
5 [mArr addObject: @ "qwer"];
6 NSLog (@ "% @", mArr);
Replace element

1 // replace
2 [mArr replaceObjectAtIndex: 2 withObject: @ "asdf"];
3 NSLog (@ "% @", mArr);
Exchange element

1 // exchange
2 [mArr exchangeObjectAtIndex: 0 withObjectAtIndex: 3];
3 NSLog (@ "% @", mArr);
 

Objective-C arrays