Strings Going Missing

#import <UIKit/UIKit.h>
#import <Parse/Parse.h>

@interface PastHoursTableViewController : UITableViewController

@property (strong, nonatomic) NSArray *uploads;
@property (strong, nonatomic) NSString *date;
@property (strong, nonatomic) NSString *crew;
@property (strong, nonatomic) NSString *timeIn;
@property (strong, nonatomic) NSString *timeOut;
@property (strong, nonatomic) NSString *hours;
@property (strong, nonatomic) NSString *objectid;
@property (strong, nonatomic) PFObject *uploadedHours;
@end
'''



Implementation File
'''IOS
#import "PastHoursTableViewController.h"
#import "OldHoursViewController.h"


@interface PastHoursTableViewController ()

@end

@implementation PastHoursTableViewController


- (void)viewDidLoad
{
    [super viewDidLoad];
    PFUser *currentUser = [PFUser currentUser];
    PFQuery *query = [PFQuery queryWithClassName:@"Hours"];
    [query whereKey:@"StudentName" equalTo:currentUser.username];
    [query orderByDescending:@"createdAt"];
    [query findObjectsInBackgroundWithBlock:^(NSArray *objects, NSError *error) {
        if (error) {
             NSLog(@"Error %@ %@", error, [error userInfo]);
        }else{
            self.uploads = objects;
            [self.tableView reloadData];
        }
    }];

}

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

#pragma mark - Table view data source

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{

    // Return the number of sections.
    return 1;
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    // Return the number of rows in the section.
    return [self.uploads count];
}


- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *cellIdentifier = @"cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier forIndexPath:indexPath];
    PFObject *hours = [self.uploads objectAtIndex:indexPath.row];
    cell.textLabel.text = [hours objectForKey:@"Date"];

    return cell;
}

-(void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{
    PFObject *selectedHours = [self.uploads objectAtIndex:indexPath.row];
    self.date = [selectedHours objectForKey:@"Date"];
    self.crew = [selectedHours objectForKey:@"Crew"];
    self.timeIn = [selectedHours objectForKey:@"TimeIn"];
    self.timeOut = [selectedHours objectForKey:@"TimeOut"];
    self.hours = [selectedHours objectForKey:@"NumberOfHours"];
    self.objectid = selectedHours.objectId;
    self.uploadedHours = selectedHours;
    NSLog(@"Date:%@ Crew:%@ Time In:%@ Time Out:%@ Hours:%@ Object ID:%@", self.date, self.crew, self.timeIn, self.timeOut, self.hours, self.objectid);
    if ([self.date length]== 0|[self.crew length]== 0|[self.timeIn length] == 0| [self.timeOut length] == 0| [self.hours length]==0) {
        UIAlertView *alertview = [[UIAlertView alloc]initWithTitle:@"Oops" message:@"Yarg" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
        [alertview show];
    }
}

/*
// Override to support conditional editing of the table view.
- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath
{
    // Return NO if you do not want the specified item to be editable.
    return YES;
}
*/

/*
// Override to support editing the table view.
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
    if (editingStyle == UITableViewCellEditingStyleDelete) {
        // Delete the row from the data source
        [tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
    } else if (editingStyle == UITableViewCellEditingStyleInsert) {
        // Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view
    }   
}
*/

/*
// Override to support rearranging the table view.
- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath
{
}
*/

/*
// Override to support conditional rearranging of the table view.
- (BOOL)tableView:(UITableView *)tableView canMoveRowAtIndexPath:(NSIndexPath *)indexPath
{
    // Return NO if you do not want the item to be re-orderable.
    return YES;
}
*/



- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
    if ([segue.identifier isEqualToString:@"showDetails"]) {
        if ([self.date length]== 0|[self.crew length]== 0|[self.timeIn length] == 0| [self.timeOut length] == 0| [self.hours length]==0) {
            UIAlertView *alertview = [[UIAlertView alloc]initWithTitle:@"Oops" message:@"Yipee" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
            [alertview show];
        }
        [segue.destinationViewController setHidesBottomBarWhenPushed:YES];
        OldHoursViewController *oldHoursViewController = (OldHoursViewController *)segue.destinationViewController;

        oldHoursViewController.dateString = self.date;
        oldHoursViewController.crewString = self.crew;
        oldHoursViewController.timeInString = self.timeIn;
        oldHoursViewController.timeOutString = self.timeOut;
        oldHoursViewController.hoursString = self.hours;
        oldHoursViewController.objectidString = self.objectid;
        oldHoursViewController.oldHours = self.uploadedHours;
        if ([oldHoursViewController.dateString length]== 0|[oldHoursViewController.crewString length]== 0|[oldHoursViewController.timeInString length] == 0| [oldHoursViewController.timeOutString length] == 0| [oldHoursViewController.hoursString length]==0) {
            UIAlertView *alertview = [[UIAlertView alloc]initWithTitle:@"Oops" message:@"WoooHooo" delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil, nil];
            [alertview show];
        }
    }
    // Get the new view controller using [segue destinationViewController].
    // Pass the selected object to the new view controller.
}


@end
'''