Converting ManagedObject to NSObject - iphone

Question

I am trying to get the data from 'Employee' Entity which has empId, Name, deptId as attributes.
// Used to Populate data in table
Employee : NSObject
#property (nonatomic, retain) NSString *name;
#property int empId;
#property int deptId;
#synthesize empId, name, deptId;
&
CDEmployee : NSManagedObject
#property (nonatomic, retain) NSString *name;
#property int empId;
#property int deptId;
- (void)convertMyData:(Employee *)emp;
#dynamic empId, name, deptId;
- (void)convertMyData:(Employee *)emp
{
self.empId = emp.empId;
self.name = emp.name;
self.deptId = emp.deptId;
}
// My code to fetch & convert data retured from db to Employee class
-(NSArray *)getAllEmployees:(NSManagedObjectContext*)context
{
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"(empId > %#)",[NSNumber numberWithInt:-1],[NSNumber numberWithInt:1]];
NSFetchRequest* req = [self createRequest:context]; // Request is correct
[req setPredicate:predicate];
NSFetchedResultsController* fetchContr = [[NSFetchedResultsController alloc] initWithFetchRequest:req managedObjectContext:context sectionNameKeyPath:nil cacheName:nil];
NSError* error = nil;
[fetchContr performFetch:&error];
NSArray *fetchedObjects = [fetchContr fetchedObjects];
NSMutableArray *result = [[[NSMutableArray alloc] init] autorelease];
for(int i = 0; i < [fetchedObjects count]; i++)
{
CDEmployee *cdEmp = [[fetchedObjects objectAtIndex:i] retain]; // just tried retaing
if (cdEmp)
{
Employee *emp = [[Employee alloc] init];
NSLog(#"Employee - %#", emp); // Shows tht is has object
[cdEmp convertMyData:emp]; //-----> Crashing here
[result addObject:emp];
[emp release];
}
}
[fetchContr release];
return result;
}
I am fetching results from core data & I am getting correct results back, but when I convert my core data result back to Employee(NSObject) class i am getting [NSManagedObject convertMyData:]: unrecognized selector sent to instance.
I tried adding another method say -(void)helloWorld to CDEmployee class & tried [cdEmp helloWorld]; but got the same crash.
Not getting why its causing the problem. I have method defined & implemented at proper place & its not even giving warning to me at compile time.

Answer 1

Here is a sample code that converts NSManagedObject to NSDictionary.
NSDictionary is even more easier to handle and operate on the data than NSObject. Also refer this Git Library for other similar iOS utility class methods.
+(NSDictionary *)convertManagedObjectToDictionary:(NSManagedObject *)managedObject{
if (!managedObject){
NSLog(#"Managed object is nil");
return nil;
}
else{
unsigned int objectsCount;
objc_property_t *objectProperties = class_copyPropertyList([managedObject class], &objectsCount);
NSMutableDictionary *dictionary = [[NSMutableDictionary alloc] init];
for(int i = 0; i < objectsCount; i++) {
objc_property_t property = objectProperties[i];
NSString *name = [NSString stringWithCString:property_getName(property) encoding:NSUTF8StringEncoding];
id object = [managedObject valueForKey:name];
[dictionary setObject:((object == nil) ? [NSNull null] : object) forKey:name];
}
free(objectProperties);
return dictionary;
}
}

Answer 2

I tried in different way & got resolved http://www.raywenderlich.com/934/core-data-tutorial-for-ios-getting-started

Answer 3

First, you should really first think about what you want to accomplish from a non-technical perspective. What is it, actually?
Second, NSManagedObject is a subclass of NSObject, which means you already have a NSObject. Congratulations, you are done!
Also, in your code you call fetchMyData but did not show us where you define it or what the code looks like. Maybe a NSManagedObject category would be in order here? But still, this begs the question why you would want to do this. Even if you were to convert into a Foundation object, such as NSDictionary as suggested in the other answer, you would still have a problem with modelling relationships...
Finally, what SDK are you using? You can't be serious if you are still not using ARC.