将一个plist文件读入core data - 包含在NSDictionary中的另一个NSDictionary

Question

将一个plist文件读入core data - 包含在NSDictionary中的另一个NSDictionary

iphonecocoa-touchcore-dataplist

4

我有一个值的属性列表需要读入Core Data。我可以读取“顶层”，但是每个项目除了字符串和数字外，还包含字典。我在获取正确的语法以读取这些方面遇到了问题。

Garden和Plant是我的两个Core Data实体。 Garden和Plant都是包含有关其自身数据的NSDictionary。花园可以包含许多植物，特定的植物可以在许多花园中，因此存在多对多的关系。

这部分有效：

我使用花园的属性列表字典来填充我的核心数据库，第一次运行时调用，如下所示：

    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];  
    if (![defaults objectForKey:@"firstRun"])
    {
        [defaults setObject:[NSDate date] forKey:@"firstRun"];
        [[NSUserDefaults standardUserDefaults] synchronize];
        [self loadGardenDataFromPlistDictionary]; 
    }

这很有效。将各种属性列表值加载到核心数据的第一级也是如此。但我在加载包含在“garden”字典内部的“plants”字典中的数据时遇到了麻烦……它是2级深度的。换句话说，名称、详细信息和注释都可以加载……但植物不能。以下是我的代码：

 -(void) loadGardenDataFromPlistDictionary{
// build path to plist; check Documents first, then Bundle.
NSArray *paths = NSSearchPathForDirectoriesInDomains (NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsPath = [paths objectAtIndex:0];
NSString *plistPath = [documentsPath stringByAppendingPathComponent:@"defaultGardenDictionary.plist"];
if (![[NSFileManager defaultManager] fileExistsAtPath:plistPath]) 
{
    // if not in documents, get property list from main bundle
    plistPath = [[NSBundle mainBundle] pathForResource:@"defaultGardenDictionary" ofType:@"plist"];
}

// read property list into memory as an NSData object
NSData *plistXML = [[NSFileManager defaultManager] contentsAtPath:plistPath];
NSString *errorDesc = nil;
NSPropertyListFormat format;

// convert static property list into dictionary object
NSDictionary *plistDictionary = (NSDictionary *)[NSPropertyListSerialization propertyListFromData:plistXML mutabilityOption:NSPropertyListMutableContainersAndLeaves format:&format errorDescription:&errorDesc];
if (!plistDictionary) 
{
    NSLog(@"Error reading plist: %@, format: %d", errorDesc, format);
}


NSManagedObjectContext *context = self.managedObjectContext;

[plistDictionary enumerateKeysAndObjectsWithOptions:NSEnumerationConcurrent usingBlock:^(id key, id object, BOOL *stop) {
    NSManagedObject *gardenManObj = [NSEntityDescription insertNewObjectForEntityForName:@"Garden" inManagedObjectContext:context];

    [gardenManObj setValue:[thisGardenDictionary objectForKey:@"name"] forKey:@"name"];
    [gardenManObj setValue:[thisGardenDictionary objectForKey:@"detail"] forKey:@"detail"];
    [gardenManObj setValue:[thisGardenDictionary objectForKey:@"notes"] forKey:@"notes"];
    [gardenManObj setValue:[thisGardenDictionary objectForKey:@"rating"] forKey:@"rating"];

    NSDictionary *thisGardenPlantsDictionary = [thisGardenDictionary objectForKey:@"plants"];
    NSLog(@"thisGardenPlantsDictionary contains %i dictionaries.", [thisGardenPlantsDictionary count]);
    //The trace statement above shows the correct number of plants in each garden dictionary. oooh... so tantalizingly close!

    //However, the next item is the dictionary of plants in this garden. It comes up blank. 
    //I don't understand the syntax to load that dictionary of plants into its corresponding dictionary of plants within a garden in core data. 

    //I deleted most of the things I've tried and failed with so far. Here's my last attempt:

    // the obvious and parallel:
    [gardenManObj setValue:[thisGardenDictionary objectForKey:@"plants"] forKey:@"plants"];
        //did not work; xCode compiler objected to "incompatible pointer types."

    //the compiler seemed to want an NSSet, so I tried:
    NSSet *thisGardenPlantsSet = [thisGardenDictionary mutableSetValueForKey:@"steps"];
        NSLog(@"thisGardenPlantsSet contains %i sets.", [thisGardenPlantsSet count]);
    [gardenManObj setValue:thisGardenPlantsSet forKey:@"steps"];
    //the compiler was fooled, but the setValue crashed at runtime.
 }];

我需要什么？

我错过了什么？

- James LeMay

1个回答

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原文链接

- TechZen · Accepted Answer

您并没有为每个Plant字典值创建一个新的托管对象。您只是试图将字典本身分配给关系，这当然行不通。

您需要添加类似以下的内容：

[gardenManObj setValue:[thisGardenDictionary objectForKey:@"rating"] forKey:@"rating"];

NSDictionary *thisGardenPlantsDictionary = [thisGardenDictionary objectForKey:@"plants"];
NSLog(@"thisGardenPlantsDictionary contains %i dictionaries.", [thisGardenPlantsDictionary count]);
NSManagedObject *plantMO;
for (Plant *eachPlant in thisGardenPlantsDictionary) {
  plantMO=[NSEntityDescription insertNewObjectForEntityForName:@"Plant" inManagedObjectContext:context];
  [plantMO setValue:[eachPlant valueForKey:@"someValue" forKey:@"someKey"]];
   //... repeat for all attributes
  [plantMO setValue:gardenManObj forKey:@"gardent"];
}

这将创建必要的Plant对象并与正确的Garden对象建立关系。