xcode - 核心数据故障信息

Question

我正在将托管记录的内容打印到文件中。我有一个主要实体，比如 MyAppEntity，以及几个相关实体(People、Place 等)。

我从文件中看到了这个输出:

/Users/david/Library/Application Support/iPhone Simulator/5.1/Applications/C9ACA218-F2D6-4623-8CAF-5FE763D10FC8/Documents/
 MyApp-0001 12.01.25 
 Summary goes here... 
 Nothing here yet. 
 Relationship 'people' on managed object (0x79eaf7f0) <NSManagedObject: 0x79eaf7f0> (entity: MyAppEntity; id: 0x79eae950 <x-coredata:/B86C9CA8-EDE4-452C-BA56-FEF50B4F0FF9/MyAppEntity/p1> ; data: {
    audioName = 00010125121910;
    audioNo = 0;
    date = nil;
    MyApp = "MyApp-0001 12.01.25";
    interpret = "Nothing here yet.";
    keyword =     (
    );
    order = 0;
    people =     (
        "0x79ee42f0 <x-coredata:/B86C9CA8-EDE4-452C-BA56-FEF50B4F0FF9/PeopleEntity/p1>",
        "0x79ee4300 <x-coredata:/B86C9CA8-EDE4-452C-BA56-FEF50B4F0FF9/PeopleEntity/p2>"
    );
    place =     (
        "0x79ee6970 <x-coredata:/B86C9CA8-EDE4-452C-BA56-FEF50B4F0FF9/PlaceEntity/p2>",
        "0x79ee6960 <x-coredata:/B86C9CA8-EDE4-452C-BA56-FEF50B4F0FF9/PlaceEntity/p1>"
    );
    recurring = 0;
    summary = "Summary goes here...";
    symbol =     (
    );
    type =     (
    );
}) with objects {(
    <NSManagedObject: 0x79ee47e0> (entity: PeopleEntity; id: 0x79ee42f0 <x-coredata:/B86C9CA8-EDE4-452C-BA56-FEF50B4F0FF9/PeopleEntity/p1> ; data: {
    definition = nil;
    name = me;
    order = 0;
    people = "<relationship fault: 0x79ef5ce0 'people'>";
}),
    <NSManagedObject: 0x79ee4a70> (entity: PeopleEntity; id: 0x79ee4300 <x-coredata:/B86C9CA8-EDE4-452C-BA56-FEF50B4F0FF9/PeopleEntity/p2> ; data: {
    definition = nil;
    name = you;
    order = 1;
    people = "<relationship fault: 0x79e60840 'people'>";
})
)} 

我有两个问题...首先，故障消息是什么意思？其次，如何检索 people.name 或 place.name.. 的值？

我可以贴出数据模型图，但它基本上是这样的:

MyAppEntity:属性: 标题 日期 细节 人际关系、地点等

人物实体:属性: 姓名 描述 命令 关系:人

PlaceEntity:属性: 姓名 描述 命令 关系:地点

关系是多对多的。这是因为一项任务可以有很多人，而同一个人可以处理多项任务。

---

在另一个 post 中感谢 Gerry 和 Marcus Zarra .我终于明白了。如果它对其他人有帮助，这是我的代码:

NSManagedObjectContext *context = [self managedObjectContext];  
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    NSEntityDescription *mainEntity = [NSEntityDescription entityForName:@"MainEntity" inManagedObjectContext:context];

    [fetchRequest setEntity:mains]; 
    NSError *error = nil;   
    NSArray *fetchedObjects = [context executeFetchRequest:fetchRequest error:&error];


    NSLog(@"Record Count is: %i", [fetchedObjects count]);

    // THIS ACTUALLY WORKS.....

     for (MainEntity *mains in fetchedObjects) {
     NSLog(@"Main: %@", mains.name);
         NSSet *peopleSet = [mains valueForKey:@"people"];   
         for (id person in peopleSet) {
             NSLog(@"name = %@", [person valueForKey:@"name"]);
         }
         NSSet *keywordSet = [mains valueForKey:@"keyword"];     
         for (id keyWord in keywordSet) {
             NSLog(@"Keyword = %@", [keyWord valueForKey:@"word"]);
         }
         NSSet *placeSet = [mains valueForKey:@"place"];     
         for (id places in placeSet) {
             NSLog(@"Place = %@", [places valueForKey:@"name"]);
         }
         NSSet *symbolSet = [mains valueForKey:@"symbol"];   
         for (id symbols in symbolSet) {
             NSLog(@"Symbol = %@", [symbols valueForKey:@"symbolName"]);
         }
         NSSet *typeSet = [mains valueForKey:@"type"];   
         for (id types in typeSet) {
             NSLog(@"Type = %@", [types valueForKey:@"typeName"]);
         }
     }

    if (!fetchedObjects || error) {
        NSLog(@"[ERROR] COREDATA: Fetch request raised an error - '%@'", [error description]);
        return;
    }

Answer 1

使用故障以便仅在需要时加载数据。当您访问该关系时，它将被加载。查看Faulting and Uniquing在Core Data Programming Guide .

一旦您访问了对多关系，您将拥有一个集合。您可以枚举集合并访问各个托管对象的属性。例如(假设 appObject 是 MyAppEntity 的实例):

for (id person in [appObject valueForKey:@"people"]) {
    NSLog(@"name = %@", [person valueForKey:@"name"]);
}