NSSet和NSOrderedSet使用

GitHub Demo: https://github.com/BaHui/NSSet_Study

简介

• NSSet: 无序不可变集合
• NSMutableSet: 无序可变集合

---

• NSOrderedSet: 有序不可变集合
• NSMutableOrderedSet: 有序可变集合

使用场景

用法与NSArray相似, 但是若是需要保证操作的集体数据中, 相同的对象只存在一份, 我们一般采用集合进行数据源的操作, 集合又分为无序集合(NSSet | NSMutableSet) 和 有序集合 (NSOrderedSet | NSMutableOrderedSet). 下面我们来了解一些集合的简单用法;

使用示例

// 我们先来验证下NSSet或NSMutableSet集合是有序还是无序的; 结论: 是无序的!
- (void)testMethodForSetOrderStatus {
    NSMutableSet *mutableSetOrder = [NSMutableSet new];
    [mutableSetOrder addObject:@"1"];
    [mutableSetOrder addObject:@"2"];
    [mutableSetOrder addObject:@"3"];
    [mutableSetOrder addObject:@"4"];
    NSLog(@"mutableSetOrderStatus: %@", mutableSetOrder);
    /* 输出: mutableSetOrderStatus: {(
     3,
     1,
     4,
     2
     )} */
}

// 向集合中加入相同的元素, 集合会自动过滤掉重复的元素.
- (void)testMethodForSetOfString {
    NSString *equalString1 = @"1";
    NSString *equalString2 = @"1";

    NSMutableSet *mutableSetEqualString  = [NSMutableSet new];
    [mutableSetEqualString addObject:equalString1];
    [mutableSetEqualString addObject:equalString2];
    NSLog(@"mutableSetEqualString: %@", mutableSetEqualString);
    /* 输出: mutableSetEqualString: {(
     1
     )} */

    NSString *notEqualString1 = @"1";
    NSString *notEqualString2 = @"2";
    NSMutableSet *mutableSetsetNotEqualString  = [NSMutableSet new];
    [mutableSetsetNotEqualString addObject:notEqualString1];
    [mutableSetsetNotEqualString addObject:notEqualString2];
    NSLog(@"mutableSetsetNotEqualString: %@", mutableSetsetNotEqualString);
    /* 输出: mutableSetsetNotEqualString: {(
     1,
     2
     )} */
}

// BHPerson是继承与NSObject的类, 因为即使属性都是相同的, 但内存地址不一样. 所以会同时存在于集合
- (void)testMethodForSetOfPerson {
    BHPerson *person1 = [BHPerson create];
    BHPerson *person2 = [BHPerson create];
    [person1 updateName:@"小明" age:20];
    [person2 updateName:@"小明" age:20];

    NSMutableSet *mutableSetPerson = [NSMutableSet new];
    [mutableSetPerson addObject:person1];
    [mutableSetPerson addObject:person2];
    NSLog(@"mutableSetPerson: %@", mutableSetPerson);
    /* 输出: mutableSetPerson: {(
     <BHPerson: 0x6000035a83a0>,
     <BHPerson: 0x6000035a8420>
     )} */
}

// BHOverwritePerson是一个继承NSObject的类, 但是对其isEqual方法进行了重写, 若名字(name属性值)是一样的,则认为是同一个对象, 所以集中只会存在一份; 
- (void)testMethodForOfOverwritePerson {
    BHOverwritePerson *overwritePerson1 = [BHOverwritePerson create];
    BHOverwritePerson *overwritePerson2 = [BHOverwritePerson create];
    [overwritePerson1 updateName:@"小明" age:20];
    [overwritePerson2 updateName:@"小明" age:20];

    NSMutableSet *mutableSetOverwritePerson = [NSMutableSet new];
    [mutableSetOverwritePerson addObject:overwritePerson1];
    [mutableSetOverwritePerson addObject:overwritePerson2];
    NSLog(@"mutableSetOverwritePerson: %@", mutableSetOverwritePerson);
    /* 输出: mutableSetOverwritePerson: {(
     <BHOverwritePerson: 0x60000379c620>
     )} */
}

// 将一个数组转化为NSMutableSet, 此时, 将会由有序的数组变为无序的NSMutableSet
- (void)testMethodForSetFromArray {
    NSArray *strigns = @[@"1", @"2", @"3", @"1"];
    NSMutableSet *setFormArray = [NSMutableSet setWithArray:strigns];
    NSLog(@"setFormArray: %@", setFormArray);
    /* 输出: setFormArray: {(
     3,
     1,
     2
     )} */
}

// 对NSSet进行排序, 返回一个数组(数组是有序的)
- (void)testMethodForOrderbySet {
    NSSet *set = [NSSet setWithObjects:@"a", @"d", @"b", @"c", @"e", nil];

    NSSortDescriptor *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:nil ascending:YES];
    NSArray *orderbyedArray = [set sortedArrayUsingDescriptors:@[sortDescriptor]];
    NSLog(@"orderbyedArray: %@", orderbyedArray);
    /* 输出: orderbyedArray: (
     a,
     b,
     c,
     d,
     e
     ) */
}

// 对元素增加或者删除
- (void)testMethodForAddAndRemoveObject {
    NSMutableSet *set = [NSMutableSet new];

    [set addObject:@"1"];
    [set addObject:@"2"];
    [set addObject:@"3"];
    NSLog(@"添加元素后: %@", set);
    /* 输出: 添加元素后: {(
     1,
     2,
     3
     )} */

    [set removeObject:@"3"];
    NSLog(@"移除元素后: %@", set);
    /* 输出: 移除元素后: {(
     1,
     2
     )} */

    [set removeAllObjects];
    NSLog(@"移除所有元素后: %@", set);
    /* 输出: 移除所有元素后: {(
     )} */
}

// 集合交集和子集的判断
- (void)testMethodForHasIntersection {
    NSMutableSet *set1 = [NSMutableSet setWithObjects:@"1", @"2", @"3", @"4", nil, nil];
    NSMutableSet *set2 = [NSMutableSet setWithObjects:@"1", @"2", nil];

    // 判断是否有交集;
    BOOL hasIntersection = [set1 intersectsSet:set2];
    NSLog(@"set1和set2是否有交集: %@", hasIntersection ? @"有" : @"无"); // 输出: set1和set2是否有交集: 有

    // 判断set2是否是set1的子集;
    BOOL isSubsetOfSet1 = [set2 isSubsetOfSet:set1];
    NSLog(@"set2是否是set1的子集: %@", isSubsetOfSet1 ? @"是" : @"否"); // 输出: set2是否是set1的子集: 是

    // 判断set2是否是set2的子集;
    BOOL isSubsetOfSet2 = [set2 isSubsetOfSet:set2];
    NSLog(@"set2是否是set2的子集: %@", isSubsetOfSet2 ? @"是" : @"否"); // 输出: set2是否是set2的子集: 是

    // 获取set1 和 set2 交集
    [set1 intersectSet:set2];
    NSLog(@"交集: %@", set1);
    /* 输出:交集: {(
     1,
     2
     )} */
}

// NSMutableOrderedSet集合是否有序; 结论: 是有序的;
- (void)testMethodForOrderedSet {
    NSMutableOrderedSet *mutableOrderedSet = [NSMutableOrderedSet new];
    [mutableOrderedSet addObject:@"1"];
    [mutableOrderedSet addObject:@"3"];
    [mutableOrderedSet addObject:@"4"];
    [mutableOrderedSet addObject:@"2"];

    NSLog(@"mutableOrderedSet: %@", mutableOrderedSet);
    /* 输出: mutableOrderedSet: {(
     1,
     3,
     4,
     2
     )} */
}

// 对有序集合的排序
- (void)testMethodForOrderbyOrderedSet {
    NSMutableOrderedSet *mutableOrderedSet = [NSMutableOrderedSet new];
    [mutableOrderedSet addObject:@"1"];
    [mutableOrderedSet addObject:@"3"];
    [mutableOrderedSet addObject:@"2"];
    [mutableOrderedSet addObject:@"5"];

    NSSortDescriptor *sortDescriptor = [NSSortDescriptor sortDescriptorWithKey:nil ascending:YES];
    [mutableOrderedSet sortUsingDescriptors:@[sortDescriptor]];
    NSLog(@"orderbyMutableOrderedSet: %@", mutableOrderedSet);
    /* 输出: orderbyMutableOrderedSet: {(
     1,
     2,
     3,
     5
     )} */
}

交流与建议

• GitHub：https://github.com/BaHui
• 邮    箱：qiaobahuiyouxiang@163.com