如何绑定Realm对象更改？

Question

在我的项目我尝试通过MVVM在VM工作， 所以在.h文件

@property (nonatomic, strong) NSArray *cities; 

在.m文件

- (NSArray *)cities { 
     return [[GPCity allObjects] valueForKey:@"name"]; 
    } 

GPCity是RLMObject子 如何通过ReactiveCocoa结合本（我是指查看所有城市的更新/添加/删除）？

喜欢的东西：

RAC(self, cities) = [[GPCity allObjects] map:(GPCity *)city {return city.name;}]; 

Answer 1

您可以在RAC信号包裹境界变更通知：

@interface RLMResults (RACSupport) 
- (RACSignal *)gp_signal; 
@end 

@implementation RLMResults (RACSupport) 
- (RACSignal *)gp_signal { 
    return [RACSignal createSignal:^(id<RACSubscriber> subscriber) { 
     id token = [self.realm addNotificationBlock:^(NSString *notification, RLMRealm *realm) { 
      if (notification == RLMRealmDidChangeNotification) { 
       [subscriber sendNext:self]; 
      } 
     }]; 

     return [RACDisposable disposableWithBlock:^{ 
      [self.realm removeNotification:token]; 
     }]; 
    }]; 
} 
@end 

然后执行：

RAC(self, cities) = [[[RLMObject allObjects] gp_signal] 
        map:^(RLMResults<GPCity *> *cities) { return [cities valueForKey:@"name"]; }]; 

这不幸的是更新后的信号每写交易，而不仅仅是那些莫dify城市。一旦境界0.98发布与support for per-RLMResults notifications，你就可以做到以下几点，当GPCity对象更新将只更新：

@interface RLMResults (RACSupport) 
- (RACSignal *)gp_signal; 
@end 

@implementation RLMResults (RACSupport) 
- (RACSignal *)gp_signal { 
    return [RACSignal createSignal:^(id<RACSubscriber> subscriber) { 
     id token = [self addNotificationBlock:^(RLMResults *results, NSError *error) { 
      if (error) { 
       [subscriber sendError:error]; 
      } 
      else { 
       [subscriber sendNext:results]; 
      } 
     }]; 

     return [RACDisposable disposableWithBlock:^{ 
      [token stop]; 
     }]; 
    }]; 
} 
@end