NSSet
1 NSSet * set = [[NSSet alloc] initWithObjects:@"one",@"two",@"three",@"four", nil]; 2 [set count]; // Returns the number of objects in the collection
1//Judge whether @ "two" exists in the collection 2 BOOL ret = [set containsObject:@"two"];
1 NSSet * set2 = [[NSSet alloc] initWithObjects:@"one",@"two",@"three",@"four", nil]; 2//Judge whether two sets are equal 3 BOOL ret = [set isEqualToSet:set2];
1 NSSet * set2 = [[NSSet alloc] initWithObjects:@"one",@"two",@"three",@"four",@"five", nil]; 2//Judge whether the set is a subset of set2 3 BOOL ret = [set isSubsetOfSet:set2];
1//Collection can also be traversed by enumerator 2 NSEnumerator * enumerator = [set objectEnumerator]; 3 NSString *str; 4 while (str = [enumerator nextObject]) { 5 …… 6 }
1 NSArray * array = [[NSArray alloc] initWithObjects:@"one",@"two",@"three",@"four", nil]; 2 NSSet * set = [[NSSet alloc] initWithArray:array];
1 NSArray * array2 = [set allObjects];
1//Variable set NSMutableSet 2 NSMutableSet * set = [[NSMutableSet alloc] init]; 3 [set addObject:@"one"]; 4 [set addObject:@"two"]; 5 [set addObject:@"two"]; // If there are duplicates in the added elements, only one is actually reserved
1//Delete elements 2 [set removeObject:@"two"]; 3 [set removeAllObjects];
1//Add the elements in set2 to the set. If there are duplicates, only one is reserved 2 NSSet * set2 = [[NSSet alloc] initWithObjects:@"two",@"three",@"four", nil]; 3 [set unionSet:set2];
1 [set minusSet:set2];
1//Index set (index set) NSIndexSet 2 NSIndexSet * indexSet = [[NSIndexSet alloc] initWithIndexesInRange:NSMakeRange(1, 3)]; // The number in the set is 123
1//Extract the elements at the specified position in the array according to the collection 2 NSArray * array = [[NSArray alloc] initWithObjects:@"one",@"two",@"three",@"four", nil]; 3 NSArray * newArray = [array objectsAtIndexes:indexSet]; // Return @ "two", @ "three", @ "four"
1 NSMutableIndexSet *indexSet = [[NSMutableIndexSet alloc] init]; 2 [indexSet addIndex:0] 3 [indexSet addIndex:3]; 4 [indexSet addIndex:5]; 5//Get the specified elements in the array through the collection 6 NSArray *array = [[NSArray alloc] initWithObjects:@"one",@"two",@"three",@"four",@"five",@"six", nil]; 7 NSArray *newArray = [array objectsAtIndexes:indexSet]; // Return @ "one", @ "four", @ "six"
