OC: Collection class in OC-NSSet (2)

OC: Collection class in OC-NSSet (2)

/*

NSSet set

In an NSSet object, a specific object can only appear once.

The greatest use of an NSSet object is to check whether an object exists. Fast

Comparison between NSSet and NSArray

Same: 1. All are used to store OC objects

2. Basic data types, struct, and enumeration cannot be directly stored.

3. They are both immutable, but all have a mutable subclass.

Difference: 1. NSArray is ordered, and NSSet is unordered.

2. The elements in NSSet are unique.

*/

// ================================================ ============================

// Create an empty set. No more elements can be added to it.

// NSSet * set1 = [NSSet set];

// Create a set with an element

NSSet * set2 = [NSSet setWithObject: @ "abc"];

// Create a set with Multiple Elements

Car * car1 = [Car new];

Car * car2 = [Car new];

NSSet * set3 = [NSSet setWithObjects: car1, car2, @ "abc", nil];

// Obtain the number of set Elements

NSUInteger count = set3.count;

[Set3 count];

NSLog (@ "% ld", count );

// Print the set (the printed element order is not fixed)

NSLog (@ "% @", set3 );

// Obtain all elements in the set. The returned value is NSArray.

NSArray * ary = [set3 allObjects];

// There is no order to retrieve an element from the set.

[Set3 anyObject];

// Determine whether an object is contained in the Set

[Set3 containsObject: @ "abc"]; // return BOOL type

If ([set3 containsObject: @ "abc"])

{

NSLog (@ "this object exists in set ");

}

Else

{

NSLog (@ "set does not contain this object ");

}

[Set3 member: @ "abc"]; // return BOOL type

If ([set3 member: @ "abc"])

{

NSLog (@ "this object exists in set ");

}

Else

{

NSLog (@ "set does not contain this object ");

}

// ================================================ ================================

// NSMutableSet variable set

// Initialize a variable set

NSMutableSet * set4 = [NSMutableSet set];

// Add Element

[Set4 addObject: [Car new];

// Add the elements in an array to the current set

NSArray * ary2 = @ [@ "jereh", @ "ios"];

[Set4 addObjectsFromArray: ary2];

NSLog (@ "% @", set4 );

// Delete. Because there is no order, you cannot delete the determined objects according to the index location.

// Delete an element

[Set4 removeObject: @ "ios"];

// Delete all elements

[Set4 removeAllObjects];

// Traverse the set (Use Quick traversal)

NSMutableSet * set5 = [NSMutableSet setWithObjects: @ "a", @ "B", @ "c", @ "d", nil];

NSArray * ary3 = @ [@ "jere"];

[Set5 addObjectsFromArray: ary2];

[Set5 addObjectsFromArray: ary3];

For (id obj in set5 ){

NSLog (@ "% @", obj );

}

// Add all elements of a set to the current set

NSLog (@ "% @", set4 );

NSLog (@ "% @", set5 );

NSMutableSet * set6 = [NSMutableSet setWithObject: @ "I love you."];

[Set6 unionSet: set5];

NSLog (@ "% @", set6 );

// Determine whether two sets are equal

If ([set5 isEqualToSet: set6] = YES ){

NSLog (@ "two sets are equal ");

}

Else

{

NSLog (@ "two sets are not equal ");

}

// Determine whether at least one element exists in the intersection of the two Sets

[Set6 intersectsSet: set5]; // BOOL

[Set6 intersectSet: set5]; // void

If ([set6 intersectsSet: set5] = YES ){

NSLog (@ "two sets have intersections ");

}

Else

{

NSLog (@ "there is no intersection between the two sets ");

}