IOS, ios9

IOS, ios9

1. Common Array Processing Methods

// -------------------- Immutable Array

// 1. Create an array

NSString * s1 = @ "zhangsan ";

NSString * s2 = @ "lisi ";

NSString * s3 = @ "wangwu ";

// (1)

NSArray * array1 = [[NSArray alloc] initWithObjects: s1, s2, s3, nil];

NSLog (@ "% @", array1); // equivalent to array1.descripton

// (2) create using the Class Method

NSArray * array2 = [NSArray arrayWithObjects: s1, s2, s3, nil];

// (3) create an array object and store an element in it

NSArray * array3 = [NSArray arrayWithObject: s1];

// (4) Create an array with elements from array1

NSArray * array4 = [NSArray arrayWithArray: array1];

NSLog (@ "array4 = % @", array4 );

// 2. Obtain elements by subscript

NSString * str1 = [array4 objectAtIndex: 0];

// 3. Number of array elements

NSUInteger count = [array4 count]; // equivalent to: array4.count;

// 4. Determine whether the array contains an element

BOOL isContains = [array4 containsObject: @ "zhangsan"];

NSLog (@ "isContains: % d", isContains );

// 5. Find the subscript position of an object in the array

NSUInteger index = [array4 indexOfObject: @ "wangwu"];

If (index = NSNotFound ){

NSLog (@ "Not find elemets ");

} Else {

NSLog (@ "index = % ld", index );

}

// 6. link the string in the array (prerequisite: All strings in the array)

NSString * joinString = [array4 componentsJoinedByString: @ ","];

NSLog (@ "joinString = % @", joinString );

// 7. Access the last element of the array

NSString * lastObj = [array4 lastObject]; // array4.lastObject

NSLog (@ "lsatObj = % @", lastObj );

// 8. Add an element to the original array.

NSArray * array5 = [array4 arrayByAddingObject: @ "zhaolia"];

NSLog (@ "array5 =%@", array5 );

// Obtain the corresponding subscript Element

Int idx = 4;

If (idx <array5.count ){

NSString * s = [array5 objectAtIndex: idx];

NSLog (@ "s = % @", s );

}

// -------------- Array Traversal

// 1. Normal Traversal

For (int I = 0; I <array5.count; I ++ ){

NSString * str = [array5 objectAtIndex: I];

NSLog (@ "% @", str );

}

// Fast Traversal

For (NSString * s in array5 ){

NSLog (@ "% @", s );

}

// Optimization after 4.4

// 1. Create a group

NSArray * array7 = @ [s1, s2, s3]; // equivalent to: NSArray * array7 = [NSArray arrayWithObjects: s1, s2, s3, nil];

NSLog (@ "array7 =%@", array7 );

NSString * str = array7 [0];

NSLog (@ "array [7] = % @", str );

// ------------------ Variable array

// Initialization. Set the number of elements to 5, which can be changed. (Inherited from NSArray)

NSMutableArray * mutableArray = [NSMutableArray arrayWithCapacity: 5];

// Add an element to the array

[MutableArray addObject: @ "aaa"];

// Insert an element to the specified subscript in the array

[MutableArray insertObject: @ "ccc" atIndex: 0];

NSLog (@ "% @", mutableArray); // move back the original position Element

// Remove the last element

[MutableArray removeLastObject];

NSLog (@ "after the last element is removed: % @", mutableArray );

// Remove the specified Element

[MutableArray removeObject: @ "aaa"];

// Remove the specified subscript Element

[MutableArray removeObjectAtIndex: 0];

// Add an array to the array

[MutableArray addObjectsFromArray: array1];

// 1. Create a variable array

NSString * t1 = @ "zhangsan ";

NSString * t2 = @ "lisi ";

NSString * t3 = @ "wangwu ";

// NSMutableArray * mArray1 = @ [s1, s2, s3]; // wrong. an unchangeable array is created here.

NSMutableArray * mArray1 = [[NSMutableArray alloc] initWithObjects: s1, s2, s3, nil];

// When creating an array, three spaces are opened for storing elements. When the storage exceeds the capacity, the array automatically increases the space.

NSMutableArray * mArray2 = [[NSMutableArray alloc] initWithCapacity: 3];

NSMutableArray * mArray3 = [NSMutableArray arrayWithCapacity: 3];

// 2. Add an element

[MArray2 addObject: t1];

[MArray2 addObject: t2];

[MArray2 addObject: t3];

NSLog (@ "mArray2 = % @", mArray2 );

// Add the elements in mArray2 to mArray3

// [MArray3 addObjectsFromArray: mArray2];

// Add mArray2 as a two-dimensional number

[MArray3 addObject: mArray2];

NSLog (@ "mArray3 = % @", mArray3 );

// 3. insert an element

[MArray2 insertObject: @ "Jack" atIndex: 0];

NSLog (@ "mArray2 = % @", mArray2 );

// 4. Replace Element

[MArray2 replaceObjectAtIndex: 0 withObject: @ "John"];

NSLog (@ "Replace: % @", mArray2 );

// 5. Swap the positions of two elements

[MArray2 exchangeObjectAtIndex: 3 withObjectAtIndex: 0];

NSLog (@ "mArray2 = % @", mArray2 );

// 6. delete an element

// 6.1 Delete according to subscript

[MArray2 removeObjectAtIndex: 2];

NSLog (@ "mArray2 = % @", mArray2 );

// 6.2 delete the last element

[MArray2 removeLastObject];

NSLog (@ "mArray2 = % @", mArray2 );

// 6.3 Delete the specified object.

// [MArray2 removeObject: @ "zhangsan"];

// 6.4 delete all elements

[MArray2 removeAllObjects];

NSLog (@ "mArray2 = % @", mArray2 );