iOS-realm使用总结

先从数据库最基本的增删查改来看realm怎么用

// 增

- (void)addObject {

    //添加数据
    Model *model = [self loadData];

    //将数据加入到数据库中
    RLMRealm *realm = [RLMRealm defaultRealm];

    [realm transactionWithBlock:^{
        [realm addObject:model];
    }];
    NSLog(@"results: %@",[Model allObjects]);
}

// 删

- (void)deleteObject {

    //获取OrderModel所有数据
    RLMResults *results = [Model allObjects];
    NSLog(@"results: %@",results);
    
    //添加数据
    Model *model =nil;
    if(results.count)  model = [results firstObject];

    //将数据加入到数据库中
    RLMRealm *realm = [RLMRealm defaultRealm];
    [realm transactionWithBlock:^{
        [realm deleteObject:model];
        [realm deleteAllObjects];
    }];
    NSLog(@"results: %@",results);
}

// 查

- (void)queryObject {

    //查询字符串时需要加上''号
    //基本用法查询字符串
    //Name对应name的数组
    RLMResults *Results = [Model objectsWithPredicate:[NSPredicate predicateWithFormat:[NSString stringWithFormat:@"Name == '%@',name"]]];

    //关于Model的检索
    //objectId大于2进行查询
    RLMResults *results = [Model objectsWhere:@"objectId > 2"];
    NSLog(@"results: %@",results);

    //objectId大于2小于6进行查询
    //    RLMResults *regionResults = [Model objectsWhere:@"objectId > 2 AND objectId < 6"];

    RLMResults *regionResults = [Model objectsWhere:@"objectId BETWEEN{2,6}"];
    NSLog(@"results: %@",regionResults);

    //关于Model的检索
    //检索Name含有l的Model（CONTAINS 包含）([c]是不区分大小写)
    RLMResults *results = [Model objectsWhere:@"Name CONTAINS[c] 'l'"];
    NSLog(@"results: %@", results);

    //检索Name为lj并且rlmModelArray的个数大于3的Model
    RLMResults *mergeResults = [[Model objectsWhere:@"Name == 'lj'"] objectsWhere:@"rlmModelArray.@count < 3"];
    NSLog(@"results: %@",mergeResults);
}

// 改

- (void)modifyObject {

    //获取Model所有数据
    RLMResults *results = [Model allObjects];
    NSLog(@"results: %@",results);

    //添加数据
    Model *model = nil;
    if (results.count)  model = [results firstObject];

    RLMRealm *realm = [RLMRealm defaultRealm];
    [realm transactionWithBlock:^{
        model.time = [NSDate date];
    }];
    NSLog(@"results: %@",results);

    //批量修改
    //获取Model所有数据

    RLMResults *modelResults = [Model allObjects];
    NSLog(@"results: %@", modelResults);

    [realm transactionWithBlock:^{
        [modelResults setValue:@(123) forKey:@"objectId"];
        
        }];
        NSLog(@"results: %@", modelResults);
    }
}

realm其余的关系与属性

// 主键（唯一性）（查询更快）

+ (NSString*)primaryKey {

    return @"modelId";
}

// 索引属性支持（NSString,NSNumber,NSDate）（可以比一般属性更快的查询）

+ (NSArray *)indexedProperties {

    return @[@"modelAttribute"];
}

// 默认属性(realm基本属性是不可以传nil的，可以在这里给个默认值0)

+ (NSDictionary*)defaultPropertyValues {

    return @{@"objectId":@(0)};
}

// 反向关系

+ (NSDictionary*)linkingObjectsProperties {

    return @{@"model" : [RLMPropertyDescriptor descriptorWithClass:Model.class propertyName:@"rlmModelArray"]};
}

// 忽略属性

+ (NSArray*)ignoredProperties {

    return @[@"ignoreName"];
}