title: Revisiting a view controller is giving me error
body: <p>Hi I don't have an array in this view controller but I am getting an error and when I visit this page first it runs fine but at my last page when I want to add an item I am coming back to this page using segue </p>
  
  <p>Note:1. When I am visiting this page the first time it goes smoothly no error</p>
  
  <p>my aim is this is the menu page for ordering food and in add cart to add new items I am revisiting this page again and it gives me an error.
  @</p>
  
  <pre><code>UIImageView *drinki = [[UIImageView alloc] init];
  </code></pre>
  
  <p>it was unwanted so I removed it and then </p>
  
  <pre><code>UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(onButtonTapped:)];
  </code></pre>
  
  <p>At this line, my app terminates </p>
  
  <p>This is my log for error</p>
  
  <pre><code> 2017-06-19 09:01:58.156 Barebones[3337:314954] *** Terminating app
  due to uncaught exception 'NSInvalidArgumentException', reason: '***
  -[__NSArrayM insertObject:atIndex:]: object cannot be nil'
      *** First throw call stack:
      (   0   CoreFoundation                      0x0000000111207b0b __exceptionPreprocess + 171  1   libobjc.A.dylib                     0x0000000110189141 objc_exception_throw + 48    2   CoreFoundation      
  0x000000011113c443 -[__NSArrayM insertObject:atIndex:] + 1603   3  
  UIKit                               0x0000000111dd6736
  -[UIView(UIViewGestures) addGestureRecognizer:] + 200   4   Barebones                           0x000000010f827cb9 -[CategoryViewController viewDidLoad] + 985
  </code></pre>
  
  <p>This my .m file</p>
  
  <pre><code>- (void)viewDidLoad {
  [super viewDidLoad];
  // Do any additional setup after loading the view.
  
  self.title = @"Welcome";
  
  UIGraphicsBeginImageContext(self.view.frame.size);
  [[UIImage imageNamed:@"background"] drawInRect:self.view.bounds];
  UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();
  
  self.view.backgroundColor = [UIColor colorWithPatternImage:image];
  
  //Left slidebutton
  _leftbarbutton.target = self.revealViewController;
  _leftbarbutton.action = @selector(revealToggle:);
  [self.view addGestureRecognizer:self.revealViewController.panGestureRecognizer];
  
  UIImageView *drinki = [[UIImageView alloc] init];
  UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(onButtonTapped:)];
  _drinksi.userInteractionEnabled = YES;
  [_drinksi addGestureRecognizer:tap];
  
  UIImageView *foodi = [[UIImageView alloc] init];
  UITapGestureRecognizer *tap1 = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(onButtonTapped1:)];
  _foodi.userInteractionEnabled = YES;
  [_foodi addGestureRecognizer:tap1];
  
  }
  - (void)onButtonTapped1:(UITapGestureRecognizer *)gestureRecognizer {
  
  [self performSegueWithIdentifier:@"p2" sender:self];
  NSLog(@"it works");
  }
  
  - (void)onButtonTapped:(UITapGestureRecognizer *)gestureRecognizer {
  //UIImageView *myImage = (UIImageView *)gestureRecognizer.view;
  
  
  [self performSegueWithIdentifier:@"p2" sender:self];
  NSLog(@"it works");
  }
  </code></pre>