Objective-C集合初识

NSArray 有序的 自然顺序

NSSet 无序的

NSSet 中不能存储重复的数据,可以用它来去除重复的数据

1.创建集合

　　1.1创建不可变集合

1     NSSet * set = [[NSSet alloc] initWithObjects:@"one",@"two",@"three", nil];
2     NSLog(@"%@",set);
3
4     NSSet * set1 = [[NSSet alloc] initWithObjects:@"one",@"two",@"one",@"three", nil];
5     NSLog(@"%@",set1);

　　1.2创建可变集合

1         NSMutableSet * muset = [[NSMutableSet alloc] initWithObjects:@"one",@"two", nil];
2
3         NSLog(@"%@",muset);

2.获取元素个数

1 NSUInteger count = [set1 count]; 2 NSLog(@"%lu",count);

3.判断是否包含对象

1     BOOL isContain = [set1 containsObject:@"T"];
2     if (isContain) {
3         NSLog(@"包含");
4     } else {
5         NSLog(@"不包含");
6     }

- (BOOL)containsObject:(ObjectType)anObject;

4.数组转换为集合

1     NSArray * arr = @[@"one",@"two",@"three",@"one"];
2     NSSet * set2 =[NSSet setWithArray:arr];
3     NSLog(@"set2 %@",set2);

5. 可变数组的增删

　　5.1 添加

1 [muset addObject:@"three"]; 2 NSLog(@"%@",muset);

　　5.2 删除

1 [muset removeObject:@"one"]; 2 NSLog(@"%@",muset);

　　　　删除全部

1 [muset removeAllObjects]; 2 NSLog(@"%@",muset);