Restkit 对象映射两个类访问错误

Question

我正在使用 RestKit 映射两类对象。当我自己做其中任何一个时，效果都很好。但是当我一起调用它们时，它会在 RKObjectMappingOperation.m 中的 449 行崩溃，

[destinationSet setSet:destinationObject];

并出现 "EXC_BAD_ACCESS" 错误。

这是我的两种映射方法：

- (RKObjectLoader *)saves
{
    // Create an object manager and connect core data's persistent store to it
    RKObjectManager *objectManager = [RKObjectManager sharedManager];
    RKManagedObjectStore* objectStore = [RKManagedObjectStore objectStoreWithStoreFilename:@"Db.sqlite"];
    objectManager.objectStore = objectStore;

    // Define our author mapping for saved places
    RKManagedObjectMapping *authorMapping = [RKManagedObjectMapping mappingForEntityWithName:@"Person"];
    [authorMapping mapAttributes:@"uid", nil];

    // Define our place mapping
    RKManagedObjectMapping *placeMapping = [RKManagedObjectMapping mappingForEntityWithName:@"Place"];
    [placeMapping mapAttributes:@"uid",@"name",@"address", nil];

    // Now, connect the two via a save
    RKManagedObjectMapping *saveMapping = [RKManagedObjectMapping mappingForEntityWithName:@"Save"];
    [saveMapping mapAttributes:@"uid", @"timestamp", nil];

    [saveMapping mapKeyPath:@"place" toRelationship:@"place" withMapping:placeMapping];
    [saveMapping mapKeyPath:@"author" toRelationship:@"author" withMapping:authorMapping];

    // We expect to find the place entity inside of a dictionary keyed "saves"
    [objectManager.mappingProvider setMapping:saveMapping forKeyPath:@"saves"];

    // Prepare our object loader to load and map objects from remote server, and send
    RKObjectLoader *objectLoader = [objectManager objectLoaderWithResourcePath:@"places/saves" delegate:self];
    objectLoader.method = RKRequestMethodGET;
    [objectLoader send];

    return objectLoader;
}

- (RKObjectLoader *)recommends
{
    // Create an object manager and connect core data's persistent store to it
    RKObjectManager *objectManager = [RKObjectManager sharedManager];
    RKManagedObjectStore* objectStore = [RKManagedObjectStore objectStoreWithStoreFilename:@"Db.sqlite"];
    objectManager.objectStore = objectStore;

    // Define our author mapping for recommended places
    RKManagedObjectMapping *authorMapping = [RKManagedObjectMapping mappingForEntityWithName:@"Person"];
    [authorMapping mapAttributes:@"uid", nil];

    // Define our place mapping
    RKManagedObjectMapping *placeMapping = [RKManagedObjectMapping mappingForEntityWithName:@"Place"];
    [placeMapping mapAttributes:@"uid",@"name",@"address", nil];

    // Now, connect the two via a recommend
    RKManagedObjectMapping *recommendMapping = [RKManagedObjectMapping mappingForEntityWithName:@"Recommend"];
    [recommendMapping mapAttributes:@"uid", @"timestamp", nil];

    [recommendMapping mapKeyPath:@"place" toRelationship:@"place" withMapping:placeMapping];
    [recommendMapping mapKeyPath:@"author" toRelationship:@"author" withMapping:authorMapping];

    // We expect to find the place entity inside of a dictionary keyed "recommends"
    [objectManager.mappingProvider setMapping:recommendMapping forKeyPath:@"recommends"];

    // Prepare our object loader to load and map objects from remote server, and send
    RKObjectLoader *objectLoader = [objectManager objectLoaderWithResourcePath:@"places/recommends" delegate:self];
    objectLoader.method = RKRequestMethodGET;
    [objectLoader send];

    return objectLoader;
}

当我调用其中一种或另一种时，它就会起作用。当我调用两者时，

[self saves];
[self recommends];

它崩溃了。知道为什么吗？

Answer 1

对 set objectManager.objectStore 的调用导致之前设置的 objectStore 从 objectManager 中释放。第一次调用 [self saves] 创建并设置一个 objectStore 对象，然后第二次调用 [self suggests] 重复此操作，从而删除第一个一组在[自我保存]中。在[self saves]开始处理期间的某个时间，原始（已释放）objectStore对象正在被访问，因此崩溃。

一个潜在的修复方法是将 objectStore setter 重构为一个单独的方法，该方法由两个方法调用，或者将其包装在 if (!objectManager.objectStore) { ... }< /代码> 声明。