Blocks and retain cycles

Before.m

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    
    // Adjust the table view's content inset when the keyboard appears/disappears
    _keyboardWillShowNotification =  [[NSNotificationCenter defaultCenter] addObserverForName:UIKeyboardWillShowNotification
                                                                                       object:nil
                                                                                        queue:nil
                                                                                   usingBlock:^(NSNotification *note)
     {
         // Adjust the table view's content inset to the top of the keyboard
         NSDictionary *keyboardInfo = [note userInfo];
         NSUInteger animationCurve = [[keyboardInfo objectForKey:UIKeyboardAnimationCurveUserInfoKey] unsignedIntegerValue];
         NSNumber *duration = [keyboardInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey];
         
         NSValue *endFrameVal = [keyboardInfo objectForKey:UIKeyboardFrameEndUserInfoKey];
         CGRect endFrame = CGRectZero;
         [endFrameVal getValue:&endFrame];
         
         [UIView animateWithDuration:[duration doubleValue]
                               delay:0
                             options:(animationCurve << 16)  // In UIViewAnimationOptions, curve options start at 0 << 16
                          animations:^
          {
              UIEdgeInsets insets = UIEdgeInsetsMake(0.0f, 0.0f, CGRectGetHeight(endFrame), 0.0f);
              self.tableView.contentInset = insets;
              self.tableView.scrollIndicatorInsets = insets;
          }
                          completion:^(BOOL finished)
          {
          }];
     }];
    
    _keyboardWillHideNotification = [[NSNotificationCenter defaultCenter] addObserverForName:UIKeyboardWillHideNotification
                                                                                      object:nil
                                                                                       queue:nil
                                                                                  usingBlock:^(NSNotification *note)
     {
         // Adjust the table view's content inset back to the bottom of the screen
         NSDictionary *keyboardInfo = [note userInfo];
         NSUInteger animationCurve = [[keyboardInfo objectForKey:UIKeyboardAnimationCurveUserInfoKey] unsignedIntegerValue];
         NSNumber *duration = [keyboardInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey];
         
         [UIView animateWithDuration:[duration doubleValue]
                               delay:0
                             options:(animationCurve << 16)
                          animations:^
          {
              self.tableView.contentInset = UIEdgeInsetsZero;
              self.tableView.scrollIndicatorInsets = UIEdgeInsetsZero;
          }
                          completion:^(BOOL finished)
          {
          }];
     }];
}

Fixed.m

- (void)viewWillAppear:(BOOL)animated
{
    [super viewWillAppear:animated];
    
    // If we don't use a weak variable, the notification blocks retain self and the view controller is never dealloc'd
    __weak MyViewController *weakSelf = self;
    
    _keyboardWillShowNotification =  [[NSNotificationCenter defaultCenter] addObserverForName:UIKeyboardWillShowNotification
                                                                                       object:nil
                                                                                        queue:nil
                                                                                   usingBlock:^(NSNotification *note)
     {
         // Adjust the table view's content inset to the top of the keyboard
         NSDictionary *keyboardInfo = [note userInfo];
         NSUInteger animationCurve = [[keyboardInfo objectForKey:UIKeyboardAnimationCurveUserInfoKey] unsignedIntegerValue];
         NSNumber *duration = [keyboardInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey];
         
         NSValue *endFrameVal = [keyboardInfo objectForKey:UIKeyboardFrameEndUserInfoKey];
         CGRect endFrame = CGRectZero;
         [endFrameVal getValue:&endFrame];
         
         [UIView animateWithDuration:[duration doubleValue]
                               delay:0
                             options:(animationCurve << 16)  // In UIViewAnimationOptions, curve options start at 0 << 16
                          animations:^
          {
              UIEdgeInsets insets = UIEdgeInsetsMake(0.0f, 0.0f, CGRectGetHeight(endFrame), 0.0f);
              weakSelf.tableView.contentInset = insets;
              weakSelf.tableView.scrollIndicatorInsets = insets;
          }
                          completion:^(BOOL finished)
          {
          }];
     }];
    
    _keyboardWillHideNotification = [[NSNotificationCenter defaultCenter] addObserverForName:UIKeyboardWillHideNotification
                                                                                      object:nil
                                                                                       queue:nil
                                                                                  usingBlock:^(NSNotification *note)
     {
         // Adjust the table view's content inset back to the bottom of the screen
         NSDictionary *keyboardInfo = [note userInfo];
         NSUInteger animationCurve = [[keyboardInfo objectForKey:UIKeyboardAnimationCurveUserInfoKey] unsignedIntegerValue];
         NSNumber *duration = [keyboardInfo objectForKey:UIKeyboardAnimationDurationUserInfoKey];
         
         [UIView animateWithDuration:[duration doubleValue]
                               delay:0
                             options:(animationCurve << 16)
                          animations:^
          {
              weakSelf.tableView.contentInset = UIEdgeInsetsZero;
              weakSelf.tableView.scrollIndicatorInsets = UIEdgeInsetsZero;
          }
                          completion:^(BOOL finished)
          {
          }];
     }];
}