kvo controller and etc

VIOSMessageHeaderView.h

//
//  VIOSMessageHeaderView.h
//  vipole
//
//  Created by Aziz Latypov on 09/11/15.
//  Copyright © 2015 vipole. All rights reserved.
//

#import <UIKit/UIKit.h>

@protocol VIOSMessageHeaderViewModelProtocol;

@interface VIOSMessageHeaderView : UITableViewHeaderFooterView

@property (strong, nonatomic) _Nullable id<VIOSMessageHeaderViewModelProtocol> viewModel;

- (_Nonnull instancetype)initWithCoder:( NSCoder * _Nonnull )aDecoder andViewModel:(_Nullable id<VIOSMessageHeaderViewModelProtocol>)viewModel NS_DESIGNATED_INITIALIZER;
- (_Nullable instancetype)initWithReuseIdentifier:(nullable NSString *)reuseIdentifier andViewModel:(_Nullable id<VIOSMessageHeaderViewModelProtocol>)viewModel NS_DESIGNATED_INITIALIZER;

// outlets

@property (strong, nonatomic) UILabel  * _Nullable nameLabel;
@property (strong, nonatomic) UILabel  * _Nullable dateLabel;

@end

VIOSMessageHeaderView.m

//
//  VIOSMessageHeaderView.m
//  vipole
//
//  Created by Aziz Latypov on 09/11/15.
//  Copyright © 2015 vipole. All rights reserved.
//

#import "VIOSMessageHeaderView.h"

#import "VIOSMessageHeaderViewModel.h"

#import "FBKVOController.h"
#import "NSObject+FBKVOController.h"

#import "NSObject+PropertyName.h"

@implementation VIOSMessageHeaderView

#pragma mark - Init -

- (_Nonnull instancetype)initWithCoder:( NSCoder * _Nonnull )aDecoder andViewModel:(_Nullable id<VIOSMessageHeaderViewModelProtocol>)viewModel
{
    self = [super initWithCoder:aDecoder];
    if (self) {
        [self configureWithViewModel:viewModel];
    }
    return self;
}

- (_Nullable instancetype)initWithReuseIdentifier:(nullable NSString *)reuseIdentifier andViewModel:(_Nullable id<VIOSMessageHeaderViewModelProtocol>)viewModel
{
    self = [super initWithReuseIdentifier:reuseIdentifier];
    if (self) {
        [self configureWithViewModel:viewModel];
    }
    return self;
}

- (instancetype)initWithReuseIdentifier:(NSString *)reuseIdentifier
{
    return [self initWithReuseIdentifier:reuseIdentifier andViewModel:nil];
}

- (instancetype)initWithCoder:(NSCoder *)aDecoder
{
    return [self initWithCoder:aDecoder andViewModel:nil];
}

#pragma mark -

- (void)configureWithViewModel:(_Nullable id<VIOSMessageHeaderViewModelProtocol>)viewModel
{
    self.viewModel = viewModel;
}

#pragma mark -

- (void)setViewModel:(id<VIOSMessageHeaderViewModelProtocol>)viewModel
{
    if (_viewModel != viewModel) {
        [self.KVOController unobserve:_viewModel];
        
        _viewModel = viewModel;
        
        __weak typeof(self) weakSelf = self;
        
        weakSelf.nameLabel.text = _viewModel.name;
        weakSelf.dateLabel.text = _viewModel.date;

        [self.KVOController observe:_viewModel
                            keyPath:keypathStringForProtocol(VIOSMessageHeaderViewModelProtocol, name)
                            options:NSKeyValueObservingOptionNew
                              block:^(id observer, id object, NSDictionary *change)
        {
            weakSelf.nameLabel.text = _viewModel.name;
        }];
        
        [self.KVOController observe:_viewModel
                            keyPath:keypathStringForProtocol(VIOSMessageHeaderViewModelProtocol, date)
                            options:NSKeyValueObservingOptionNew
                              block:^(id observer, id object, NSDictionary *change)
         {
             weakSelf.dateLabel.text = _viewModel.date;
         }];
    }
}

#pragma mark - Dealloc -

- (void)dealloc
{
    [self.KVOController unobserveAll];
}

@end

VIOSMessageHeaderViewModel.h

//
//  VIOSMessageHeaderViewModel.h
//  vipole
//
//  Created by Aziz Latypov on 09/11/15.
//  Copyright © 2015 vipole. All rights reserved.
//

#import "VIOSViewModel.h"

@protocol VIOSMessageHeaderViewModelProtocol <NSObject>

@property (readonly, nonatomic) NSString *name;
@property (readonly, nonatomic) NSString *date;

@end

@interface VIOSMessageHeaderViewModel : VIOSViewModel <VIOSMessageHeaderViewModelProtocol>

@property (strong, nonatomic) NSString *name;
@property (strong, nonatomic) NSString *date;

@end