MVVM架构浅析

@interface ViewController ()
@property (nonatomic, strong) LoginViewModel *loginViewModel;
@property (weak, nonatomic) IBOutlet UITextField *accountField;
@property (weak, nonatomic) IBOutlet UITextField *pwdField;
@property (weak, nonatomic) IBOutlet UIButton *loginBtn;
@end
- (LoginViewModel *)loginViewModel
{
    if (_loginViewModel == nil) {
       _loginViewModel = [[LoginViewModel alloc] init];
    }
   return _loginViewModel;
}
// 视图模型绑定
- (void)bindModel
{
    // 给模型的属性绑定信号
    // 只要账号文本框一改变，就会给account赋值
    RAC(self.loginViewModel.account, account) = _accountField.rac_textSignal;
    RAC(self.loginViewModel.account, pwd) = _pwdField.rac_textSignal;
    // 绑定登录按钮
    RAC(self.loginBtn,enabled) = self.loginViewModel.enableLoginSignal;
    // 监听登录按钮点击
   [[_loginBtn rac_signalForControlEvents:UIControlEventTouchUpInside] subscribeNext:^(id x) {
    // 执行登录事件
    [self.loginViewModel.LoginCommand execute:nil];
  }];
}

@interface LoginViewModel : NSObject
@property (nonatomic, strong) Account *account;
// 是否允许登录的信号
@property (nonatomic, strong, readonly) RACSignal *enableLoginSignal;
@property (nonatomic, strong, readonly) RACCommand *LoginCommand;
@end
@implementation LoginViewModel
- (Account *)account
{
      if (_account == nil) {
       _account = [[Account alloc] init];
     }
     return _account;
}
- (instancetype)init
{
       if (self = [super init]) {
          [self initialBind];
      }
      return self;
}
// 初始化绑定
- (void)initialBind
{
     // 监听账号的属性值改变，把他们聚合成一个信号。
     _enableLoginSignal = [RACSignal combineLatest:@[RACObserve(self.account, account),RACObserve(self.account, pwd)] reduce:^id(NSString *account,NSString *pwd){
     return @(account.length && pwd.length);
    }];
     // 处理登录业务逻辑
    _LoginCommand = [[RACCommand alloc] initWithSignalBlock:^RACSignal *(id input) {
  NSLog(@"点击了登录");
  return [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
      // 模仿网络延迟
      dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(0.5 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
          [subscriber sendNext:@"登录成功"];
          // 数据传送完毕，必须调用完成，否则命令永远处于执行状态
          [subscriber sendCompleted];
      });
      return nil;
    }];
  }];
  // 监听登录产生的数据
  [_LoginCommand.executionSignals.switchToLatest subscribeNext:^(id x) {
   if ([x isEqualToString:@"登录成功"]) {
      NSLog(@"登录成功");
   }
  }];
// 监听登录状态
[[_LoginCommand.executing skip:1] subscribeNext:^(id x) {
  if ([x isEqualToNumber:@(YES)]) {
      // 正在登录ing...
      // 用蒙版提示
      [MBProgressHUD showMessage:@"正在登录..."];
    }else
    {
         // 登录成功
         // 隐藏蒙版
         [MBProgressHUD hideHUD];
      }
   }];
 }

#import "ViewController.h"
#import "JKGlobalHeader.h"
/**
 *  VM层
 */
#import "RequestViewModel.h"
#import "DataModel.h"
#define WIDTH   [UIScreen mainScreen].bounds.size.width
#define HEIGHT  [UIScreen mainScreen].bounds.size.height
@interface ViewController ()
@property(nonatomic,strong) RequestViewModel *requestViewModel;
@property (nonatomic, strong) UITableView *tableView;
@end
@implementation ViewController
 - (void)viewDidLoad {
      [super viewDidLoad];
     //导航栏的操作
    [self daohanglan];
// 创建tableView
self.tableView = [[UITableView alloc]initWithFrame:CGRectMake(0, 0, WIDTH, HEIGHT-64)];
self.tableView.dataSource = self.requestViewModel;
self.tableView.delegate = self.requestViewModel;
self.requestViewModel.tabview = self.tableView;
[self.view addSubview:self.tableView];
/**
 *  在这里也可以拿到数据
 */
   [self.requestViewModel.requestCommand.executionSignals.switchToLatest subscribeNext:^(id x) {
    NSLog(@"%@",x);
}];
   [self.requestViewModel.requestCommand execute:@"开始"];
}
#pragma mark 导航栏
-(void)daohanglan{
   self.edgesForExtendedLayout = UIRectEdgeNone;
   self.title = @"MVVM的初次使用";
   self.navigationController.navigationBar.barTintColor = [UIColor brownColor];
   self.navigationController.navigationBar.titleTextAttributes = @{NSFontAttributeName:[UIFont systemFontOfSize:22],NSForegroundColorAttributeName:[UIColor whiteColor]};
}
//懒加载
-(RequestViewModel *)requestViewModel
{
   if (!_requestViewModel) {
     _requestViewModel = [[RequestViewModel alloc]init];
  }
  return _requestViewModel;
}
@end

#import <Foundation/Foundation.h>
 #import "JKGlobalHeader.h"
 @interface RequestViewModel : NSObject<UITableViewDelegate,UITableViewDataSource>
 /**
  *  请求命令
  */
 @property(nonatomic,strong,readonly) RACCommand *requestCommand;
 /**
  *  建立表格
  */
 @property(nonatomic,strong) UITableView *tabview;
 //模型数组
 @property (nonatomic, strong, readonly) NSArray *models;
 @end

/**
   *  把请求用一个信号包裹起来
   */
  RACSignal *signal = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
      // 1.创建请求管理者
      AFHTTPRequestOperationManager *mgr = [AFHTTPRequestOperationManager manager];
      //2.开始请求//count
      [mgr GET:@"https://api.douban.com/v2/book/search" parameters:@{@"q":@"美女"} success:^(AFHTTPRequestOperation * _Nonnull operation, id  _Nonnull responseObject) {
          NSLog(@"请求成功");
          NSArray *array =responseObject[@"books"];
          array = [DataModel mj_objectArrayWithKeyValuesArray:array];
          [subscriber sendNext:array];
      } failure:^(AFHTTPRequestOperation * _Nonnull operation, NSError * _Nonnull error) {
          NSLog(@"请求失败==%@",error);
      }];
      return nil;
  }];
  return signal;

// 有了新数据，刷新表格
  _models = x;
  // 刷新表格
  [self.tabview reloadData];
 }];

RequestTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:ID];
  if (!cell) {
     cell = [[[NSBundle mainBundle]loadNibNamed:@"RequestTableViewCell" owner:self options:nil]lastObject];
     cell.selectionStyle = UITableViewCellSelectionStyleNone;
 }
  DataModel *model = self.models[indexPath.row];
  NSURL *url = [NSURL URLWithString:model.image];
  [cell.picture sd_setImageWithURL:url placeholderImage:nil];
  cell.bookName.text = model.title;
  return cell;