NSManagedObjectContext returns nil in Core Data app (iOS) - objective-c

Question

I'm trying to save a string into a database every time a button is pressed but when I run the project, I get that on my console: 'NSInvalidArgumentException', reason: '+entityForName: nil is not a legal NSManagedObjectContext parameter searching for entity name 'Info''.
Referring to the Data Model, I have created a .xcdatamodeld with an Entity named 'Info' and, inside it, an attribute named 'path' with a type of string.
I've created three functions. "enterdata" Checks if the name is avaliable or not by calling "findData". If the name is avaliable, a new data is recorded throught "newData", if not, it looks for a different name.
I've been looking for some similar questions and I've found out this. It says that de ManagedObjectContext has to be passed to the View Controller but I don't understand what does it mean.
Here's my .h code:
#property (readonly, strong, nonatomic) NSManagedObjectContext *managedObjectContext;
Here's my .m code:
#import <CoreData/CoreData.h>
#synthesize managedObjectContext;
int iSavedNum = 1;
bool bCanSave;
//Enter data
- (IBAction) enterdata:(id)sender {
//Search if data is already registered
NSString *docDir = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSString *path = [NSString stringWithFormat:#"%#/info%i.png",docDir, iSavedNum];
[self findData:path :#"path"];
//If data is already saved, save it with new name.
if (bCanSave == NO) {
for (iSavedNum = 1; bCanSave == YES; iSavedNum++) {
[self findData:path :#"path"];
if (bCanSave == YES) {
[self newData:path :#"path"];
}
}
} else {
[self newData:path :#"path"];
}
}
//Input new data
- (void) newData:(NSString *)value:(NSString *)key {
//Create ManagedObjectContext and ManagedObjectModel
__0AppDelegate *appDelegate = (__0AppDelegate *)[[UIApplication sharedApplication] delegate];
NSManagedObjectContext *context = [appDelegate managedObjectContext];
NSManagedObjectModel *newRecord;
//Put the data to the Entity
NSString *entityName = #"Info";
newRecord = [NSEntityDescription insertNewObjectForEntityForName:entityName inManagedObjectContext:context];
[newRecord setValue:value forKey:key];
//Errors management and cheking
NSError *error;
[context save:&error];
NSLog(#"Info Saved. Value: %# Key: %#", value, key);
}
//Find Data
- (void) findData:(NSString *)valor:(NSString *)key {
//Create ManagedObjectContext
__0AppDelegate *appDelegate = (__0AppDelegate *)[[UIApplication sharedApplication] delegate];
NSManagedObjectContext *context = [appDelegate managedObjectContext];
//Call the Entity and make a request
NSString *entityName = #"Info";
NSEntityDescription *entityDesc = [NSEntityDescription entityForName:entityName inManagedObjectContext:context];
NSFetchRequest *request = [[NSFetchRequest alloc] init];
[request setEntity:entityDesc];
//Create predicate to call specific info
NSPredicate *pred = [NSPredicate predicateWithFormat:#"(%# = %#)", key, valor];
[request setPredicate:pred];
//Errors management and creation of an array with found info
NSError *error;
NSArray *objects = [context executeFetchRequest:request error:&error];
//Set if the name is avaliable or not
if ([objects count] == 0) {
bCanSave = YES;
} else {
bCanSave = NO;
}
}

Answer 1

It tells you exactly what the error is:
nil is not a legal NSManagedObjectContext parameter
That means that on this line:
newRecord = [NSEntityDescription insertNewObjectForEntityForName:entityName
inManagedObjectContext:context];
The variable context is nil. This means that your managedObjectContext method isn't working correctly. You don't show this so there's not much more we can add.

Answer 2

In application:didFinishLaunchingWithOptions: in appDelegate
/*initiate the managed Object Context */
CoreDataManager *coreDataManager = [CoreDataManager sharedDataManager];
coreDataManager.managedObjectContext = self.managedObjectContext;
where CoreDataManager is my core date manager which explicitly contains all the core data save, delete methods
Or
yourClassObject.managedObjectContext = self.managedObjectContext;
so context get initialized