Question

I created an entity with a float attribute and set it’s value to 0.5

+(void)createSportNamed:(NSString *)name withContext:(NSManagedObjectContext *)context{
Sport *newSport = [NSEntityDescription insertNewObjectForEntityForName:@"Sport" inManagedObjectContext:context];
    newSport.name = name;
    newSport.maxRep = [NSNumber numberWithInt:45];
    newSport.endurance = [NSNumber numberWithFloat:0.5f];
    NSLog(@"endurance at set = %f",[newSport.endurance floatValue]);

NSError *saveError = nil;
[context save:&saveError];
}

From the log, the value of the float is still 0.5000

But when I fetch it later on, the value somehow became 0.0000

-(NSArray*)createWorkoutForSport:(NSString*)sportName withContext:(NSManagedObjectContext*)context{

NSFetchRequest *request = [NSFetchRequest new];
request.entity = [NSEntityDescription entityForName:@"Sport" inManagedObjectContext:context];
NSPredicate *sportNamePredicate = [NSPredicate predicateWithFormat:@"name == %d",sportName];
request.predicate = sportNamePredicate;
NSError *err = nil;
NSArray *results = [context executeFetchRequest:request error:&err];
Sport *theFetchedSport = [results lastObject];

int totalRep = [[theFetchedSport maxRep]intValue];
float endure = [[theFetchedSport endurance]floatValue];
int set;
NSLog(@"Endurance = %f",endure);

Answer 1

+(void)createSportNamed:(NSString *)name withContext:(NSManagedObjectContext *)context{
  Sport *newSport = [NSEntityDescription insertNewObjectForEntityForName:@"Sport" inManagedObjectContext:context];
  newSport.name = name;

This clearly shows that the “name” field of your Sport entity is a string.

[NSPredicate predicateWithFormat:@"name == %d",sportName]

And yet here you are using %d, which means int. You’re casting a string pointer to an int. You should be using %@. Thus, your fetch request is returning an empty array, and -lastObject is returning nil, which means that [nil endurance] is also nil, which means that [[nil endurance] floatValue] is also nil, or 0.