UITableViewCell and its ViewModel persistency in memory - ios

Question

I noticed that my iOS app memory consumption is increasing while I'm scrolling table view. Using Allocations instrument I found out that some of table view cells are not retained and corresponding view models are not retained at all. What can be causing it? Memory leaks instrument didn't find any problems and I don't see any strong reference to the VM that can hold it into memory.
Here is code from tableView delegate/datasource:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
id<STReactiveView> cell = [tableView dequeueReusableCellWithIdentifier:_cellId];
STContact *contact;
if(!_searchController.active) {
contact = [[_arrangedData objectForKey:[_sectionTitles objectAtIndex:indexPath.section]] objectAtIndex:indexPath.row];
}
else
contact = [_filteredData objectAtIndex:indexPath.row];
STContactsListItemViewModel *cellVM = [[STContactsListItemViewModel alloc] initWithContact:contact services:_services];
[cell bindViewModel:cellVM];
UITableViewCell *returnCell = (UITableViewCell *)cell;
return returnCell;
}
And from cell class:
#interface STContactViewCell()
#property (strong, nonatomic) IBOutlet UILabel *nameLabel;
#property (strong, nonatomic) IBOutlet UIButton *phoneButton;
#property (strong, nonatomic) IBOutlet UIButton *messageButton;
#property (strong, nonatomic) IBOutlet UILabel *statusLabel;
#property (strong, nonatomic) IBOutlet UIImageView *photoView;
#property (strong, nonatomic) IBOutlet UIImageView *statusImage;
#property (strong, nonatomic) STContactsListItemViewModel *viewModel;
#end
#implementation STContactViewCell
-(void)bindViewModel:(id)viewModel {
_viewModel = viewModel;
[self initialize];
}
-(void)initialize {
self.nameLabel.text = _viewModel.contact.name;
self.statusLabel.text = _viewModel.contact.statusText;
self.photoView.contentMode = UIViewContentModeScaleToFill;
if(_viewModel.contact.photo)
[self.photoView setImage:_viewModel.contact.photo];
else {
if(_viewModel.contact.url.length)
[self.photoView sd_setImageWithURL:[NSURL URLWithString:_viewModel.contact.url]];
else
[self.photoView setImage:[UIImage imageNamed:#"ContactPlaceholder"]];
}
[_statusImage setImage:[UIImage imageNamed:[NSString stringWithFormat:#"Status%#",_viewModel.contact.status]]];
[_phoneButton setImage:[UIImage imageNamed:[NSString stringWithFormat:#"Phone%#",_viewModel.contact.status]]forState:UIControlStateNormal];
[_phoneButton setImage:[UIImage imageNamed:[NSString stringWithFormat:#"Phone%#Dim",_viewModel.contact.status]]forState:UIControlStateHighlighted];
[_messageButton setImage:[UIImage imageNamed:[NSString stringWithFormat:#"Message%#",_viewModel.contact.status]]forState:UIControlStateNormal];
[_messageButton setImage:[UIImage imageNamed:[NSString stringWithFormat:#"Message%#Dim",_viewModel.contact.status]]forState:UIControlStateHighlighted];
_photoView.layer.cornerRadius = _photoView.frame.size.width/2;
_photoView.layer.masksToBounds = YES;
[_photoView setContentMode:UIViewContentModeScaleAspectFill];
_phoneButton.rac_command = _viewModel.executePhoneCall;
_messageButton.rac_command = _viewModel.executeMessageSend;
if([_viewModel.contact.status isEqualToString:#"Unavailable"]) {
[_phoneButton setEnabled:NO];
[_messageButton setEnabled:NO];
}
}
And last but not the least, screenshot of allocations: