Program crashing after trying to read a NSString - ios

Question

My program:
I have view parentView and childView. childView has a UITextField. This UITextField is completed by the user. Then UITextField.text is passed as a NSString to parentView via a NSNotificationCenter. The NSLog in the Notification method shows that the value has been passes successfully to parentView.
Now the issue.... when I try to access _guideDescription (that contains the value being passed) in the saveIntoExisting my app crashes. I dont understand why is crashing when it was able to retrieve the value in the notification method.
There is no error just (llbs).
Anyone has an idea why is this happening?
- (void)viewWillAppear:(BOOL)animated {
[[NSNotificationCenter defaultCenter]
addObserver:self
selector:#selector(notificationSelectedDescription:)
name:#"selectedDescription"
object:nil];
}
- (void) notificationSelectedDescription:(NSNotification *)notification {
_guideDescription = [[notification userInfo] valueForKey:#"selected"];
NSLog(#"Show me: %#",[_guideDescription description]);
}
- (IBAction)createExercise:(UIButton *)sender {
if (![self fetch]) {
NSLog(#"It doesnt exist already");
[self save];
} else {
NSLog(#"It does exist already");
/*
* ADD CODE ON HOW TO ACT WHEN EXISTS
*/
[self saveIntoExisting];
}
}
- (void) saveIntoExisting {
NSLog(#"saveintoExisting 1");
NSLog(#"saveintoExisting show me: %#",[_guideDescription description]);
NSFetchRequest *fetchExercise = [[NSFetchRequest alloc] init];
NSEntityDescription *entityItem = [NSEntityDescription entityForName:#"Exercise" inManagedObjectContext:context];
[fetchExercise setEntity:entityItem];
[fetchExercise setPredicate:[NSPredicate predicateWithFormat:#"exerciseName == %#",_originalExerciseName]];
[fetchExercise setRelationshipKeyPathsForPrefetching:[NSArray arrayWithObjects:#"User", nil]];
fetchExercise.predicate = [NSPredicate predicateWithFormat:#"user.email LIKE %#",_appDelegate.currentUser];
NSError *error = nil;
NSArray* oldExercise = [[context executeFetchRequest:fetchExercise error:&error] mutableCopy];
Exercise *newExercise = (Exercise*) oldExercise[0];
newExercise.exerciseName = _exerciseName.text;
newExercise.exercisePic = _selectedImage;
if (![_guideDescription isEqualToString:#""]) {
newExercise.exerciseDescription =_guideDescription;
}
if (_youTubeLink){
newExercise.youtube =_youTubeLink;
}
if (![_selectRoutine.titleLabel.text isEqualToString:#"add to routine"]) {
newExercise.routine = [[self getCurrentRoutine] exercise];
[[self getCurrentUser] addRoutines:[[self getCurrentRoutine] exercise]];
}
[[self getCurrentUser] addExercisesObject:newExercise];
error = nil;
[context save:&error ];
}

Answer 1

The problem is probably that that _guideDescription string already is deallocated when you try to access it in -saveIntoExisted. You are now doing
_guideDescription = [[NSString alloc] initWithString:[[notification userInfo] valueForKey:#"selected"]];
and that works, but I would recommend:
[_guideDescription retain];
That makes sure the system doesn't deallocate the string.