How to use methods from NSManagedObject entity using NSManagedObject - iphone

Question

I am using a NSManagedObject to save some values, but not using entity for that. Because I want to not limit it to some entities. I tried using (Oist *)managedObject.entity, not working. How to use this managedObject to get theIt's like this:
Oist.h
#class File;
#interface Oist : NSManagedObject
#property (nonatomic, retain) NSSet *files;
#end
#interface Oist (CoreDataGeneratedAccessors)
- (void)addFilesObject:(File *)value;
File.h
#class Oist;
#interface File : NSManagedObject
#property (nonatomic, retain) Oist *gist;
#end
- (void)newManagedObjectWithClassName:(NSString *)className forRecords:(NSDictionary *)records
{
NSManagedObject *newManagedObject = [NSEntityDescription insertNewObjectForEntityForName:className inManagedObjectContext:[[GPCoreDataController sharedInstance] backgroundManagedObjectContext]];
[records enumerateKeysAndObjectsUsingBlock:^(id key, id obj, BOOL *stop) {
[self setValue:obj forKey:key forManagedObject:newManagedObject];
}];
}
- (void)setValue:(id)value forKey:(NSString *)key forManagedObject:(NSManagedObject *)managedObject
{
File *fileEntity = [NSEntityDescription insertNewObjectForEntityForName:#"File" inManagedObjectContext:[[GPCoreDataController sharedInstance] backgroundManagedObjectContext]];
if ([key isEqualToString:#"files"])
{
NSDictionary *files = (NSDictionary *)value;
for (NSString *key in [files allKeys]) {
NSDictionary *file = [files valueForKey:key];
NSLog(#"%#", file[#"filename"]);
[fileEntity setValue:file[#"filename"] forKey:#"filename"];
[fileEntity setValue:file[#"type"] forKey:#"type"];
}
} else if ([key isEqualToString:#"id"])
{
if ([managedObject.entity.name isKindOfClass:[Oist class]]) {
//here I want to use Oist's method - (void)addFilesObject:(File *)value; how to do that?
}
[managedObject setValue:[NSNumber numberWithInt:[value integerValue]] forKey:#"gistID"];
}
}

Answer 1

I may be misunderstanding your question, but it looks like you're hoping to cast a generically typed (NSManagedObject *) as a more specifically typed subclass.
The way to check if the pointer passed generically is in fact an instance of your subclass is this:
if ([managedObject isKindOfClass:[Oist self]]) {
// managedObject may safely be cast to an Oist*
}
You can do the cast without an assignment, like this:
[(Oist *)managedObject addFiles...];
Or, with proper parentheses, access a property (the dot operator has higher precedence than the cast, so you need to tell the compiler you want the cast first):
((Oist *)managedObject).entity
But I think that's less clear to the reader and potentially more keystrokes than an explicit assignment with a cast, which is what I'd recommend:
if ([managedObject isKindOfClass:[Oist self]]) {
Oist *oist = (Oist *)managedObject;
[oist addFilesObject:someFilesObject];
}