OC基础数据类型-NSSet

1 //判断集合中是否拥有@“two”
2 BOOL ret = [set containsObject:@"two"];

1 NSSet * set2 = [[NSSet alloc] initWithObjects:@"one",@"two",@"three",@"four", nil];
2 //判断两个集合是否相等
3 BOOL ret = [set isEqualToSet:set2];

1 NSSet * set2 = [[NSSet alloc] initWithObjects:@"one",@"two",@"three",@"four",@"five", nil];
2 //判断set是否是set2的子集合
3 BOOL ret = [set isSubsetOfSet:set2];

1 //集合也可以用枚举器来遍历
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 //可变集合NSMutableSet
2 NSMutableSet * set = [[NSMutableSet alloc] init];
3 [set addObject:@"one"];
4 [set addObject:@"two"];
5 [set addObject:@"two"]; //如果添加的元素有重复，实际只保留一个

1 //删除元素
2 [set removeObject:@"two"];
3 [set removeAllObjects];

1 //将set2中的元素添加到set中来，如果有重复，只保留一个
2 NSSet * set2 = [[NSSet alloc] initWithObjects:@"two",@"three",@"four", nil];
3 [set unionSet:set2];

1 [set minusSet:set2];

1 //指数集合（索引集合）NSIndexSet
2 NSIndexSet * indexSet = [[NSIndexSet alloc] initWithIndexesInRange:NSMakeRange(1, 3)]; //集合中的数字是123

1 //根据集合提取数组中指定位置的元素
2 NSArray * array = [[NSArray alloc] initWithObjects:@"one",@"two",@"three",@"four", nil];
3 NSArray * newArray = [array objectsAtIndexes:indexSet]; //返回@"two",@"three",@"four"

1 NSMutableIndexSet *indexSet = [[NSMutableIndexSet alloc] init];
2 [indexSet addIndex:0]
3 [indexSet addIndex:3];
4 [indexSet addIndex:5];
5 //通过集合获取数组中指定的元素
6 NSArray *array = [[NSArray alloc] initWithObjects:@"one",@"two",@"three",@"four",@"five",@"six", nil];
7 NSArray *newArray = [array objectsAtIndexes:indexSet]; //返回@"one"，@"four"，@"six"