Getting a min value of CoreData entity.

MinValue

NSFetchRequest *request = [[NSFetchRequest alloc] init];
            NSEntityDescription *entity = [NSEntityDescription entityForName:@"Slide" inManagedObjectContext:[[manager getAppDelegate]managedObjectContext]];
            [request setEntity:entity];
            
            // Specify that the request should return dictionaries.
            [request setResultType:NSDictionaryResultType];
            
            NSExpression *keyPathExpression = [NSExpression expressionForKeyPath:@"order"];
            // Create an expression to represent the minimum value at the key path 'creationDate'
            NSExpression *minExpression = [NSExpression expressionForFunction:@"min:" arguments:[NSArray arrayWithObject:keyPathExpression]];
            NSExpressionDescription *expressionDescription = [[NSExpressionDescription alloc] init];
            
            // The name is the key that will be used in the dictionary for the return value.
            [expressionDescription setName:@"minDate"];
            [expressionDescription setExpression:minExpression];
            [expressionDescription setExpressionResultType:NSObjectIDAttributeType];
            
            // Set the request's properties to fetch just the property represented by the expressions.
            [request setPropertiesToFetch:[NSArray arrayWithObject:expressionDescription]];
            
            // Execute the fetch.
            NSError *error = nil;
            NSArray *objects = [[[manager getAppDelegate]managedObjectContext] executeFetchRequest:request error:&error];
            if (objects == nil) {
                // Handle the error.
            }
            else {
                if ([objects count] > 0) {
                    NSLog(@"Object  %@",[objects objectAtIndex:0]);
                    NSLog(@"Minimum date: %@", [[objects objectAtIndex:0] valueForKey:@"minDate"]);
                }
            }