IOS MVVM 设计模式

开篇
转载自
MVC Model-View-Controller是一个用来组织代码的权威范式。Apple甚至是这么说的。在MVC下，所有的对象被归类为一个model，一个view，或一个controller。Model持有数据，View显示与用户交互的界面，而View Controller调解Model和View之间的交互。 MVVM MVVM的出现主要是为了解决在开发过程中Controller越来越庞大的问题，变得难以维护，所以MVVM把数据加工的任务从Controller中解放了出来，使得Controller只需要专注于数据调配的工作，ViewModel则去负责数据加工并通过通知机制让View响应ViewModel的改变。

效果图

源码分析
1.Model模块

首先是model层的代码，创建MovieModel类，继承自NSObject。设置几个属性movieName、year、imageUrl、detailUrl（用于跳转）

#import <Foundation>@interface MovieModel : NSObject@property (strong, nonatomic) NSString *movieName;@property (strong, nonatomic) NSString *year;@property (strong, nonatomic) NSURL *imageUrl;@property (strong, nonatomic) NSString *detailUrl;@end

ViewController模块

ViewController里面是用来从MovieViewModel中获取数据信息然后展示到UITableView的cell上面，和点击单元格的页面跳转

#import "HomeViewController.h"#import "MovieViewModel.h"#import "MovieCell.h"@interface HomeViewController ()<UITableViewDataSource>@property (nonatomic,strong) NSArray *modelArray;@end@implementation HomeViewController- (void)viewDidLoad {    [super viewDidLoad];    self.title = @"电影首页";    self.view.backgroundColor = [UIColor redColor];    UITableView *tableView = [[UITableView alloc] initWithFrame:self.view.bounds style:UITableViewStylePlain];    tableView.dataSource = self;    tableView.delegate = self;    tableView.rowHeight = 80;    [self.view addSubview:tableView];    [tableView registerClass:[MovieCell class] forCellReuseIdentifier:@"MovieCell"];    //初始化MovieViewModel，设置成功（returnBlock）和失败的回调（errorBlock），getMovieData去请求数据，请求数据成功即回调上一步设置的returnBlock，请求失败则回调errorBlock    MovieViewModel *viewModel = [[MovieViewModel alloc] init];    viewModel.returnBlock = ^(id returnValue){        _modelArray = returnValue;        [tableView reloadData];    };    viewModel.errorBlock = ^(id errorCode){        NSLog(@"%@",errorCode);    };    [viewModel getMovieData];}#pragma mark - UITableViewDataSource- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{    return _modelArray.count;}- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{    MovieCell *cell = [tableView dequeueReusableCellWithIdentifier:@"MovieCell"];    cell.model = _modelArray[indexPath.row];    return cell;}- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath{    MovieViewModel *movieViewModel = [[MovieViewModel alloc] init];    [movieViewModel movieDetailWithPublicModel:_modelArray[indexPath.row] WithViewController:self];}@end

View模块

view这里跟MVC中子类化UITableViewCell一样，将model数据传进来，复写setModel方法给视图传递数据

#import "MovieModel.h"@interface MovieCell : UITableViewCell@property (nonatomic,strong) MovieModel *model;@end#import "MovieCell.h"#import "UIImageView+AFNetworking.h"@interface MovieCell()@property (nonatomic,strong) UILabel *nameLabel;@property (nonatomic,strong) UILabel *yearLabel;@property (nonatomic,strong) UIImageView *imgView;@end@implementation MovieCell- (instancetype)initWithStyle:(UITableViewCellStyle)style reuseIdentifier:(NSString *)reuseIdentifier{    self = [super initWithStyle:style reuseIdentifier:reuseIdentifier];    if (self) {        _imgView = [[UIImageView alloc] initWithFrame:CGRectMake(15, 10, 40, 60)];        [self.contentView addSubview:_imgView];        _nameLabel = [[UILabel alloc] initWithFrame:CGRectMake(70, 10, 200, 20)];        [self.contentView addSubview:_nameLabel];        _yearLabel = [[UILabel alloc] initWithFrame:CGRectMake(70, 50, 100, 20)];        _yearLabel.textColor = [UIColor lightGrayColor];        _yearLabel.font = [UIFont systemFontOfSize:14];        [self.contentView addSubview:_yearLabel];    }    return self;}- (void)setModel:(MovieModel *)model{    _model = model;    _nameLabel.text = _model.movieName;    _yearLabel.text = _model.year;    [_imgView setImageWithURL:_model.imageUrl];}@end

ViewModel模块

ViewModel是最重要的模块： 1.这里面进行了数据的网络请求，并将数据转换成model放在一个数组中，调用_returnBlock将model数组传递给viewController进行数据源的处理 2.将页面跳转的逻辑放在ViewModel中，点击单元格进行页面跳转的时候直接在- (void)tableView:(UITableView )tableView didSelectRowAtIndexPath:(NSIndexPath )indexPath中调用MovieViewModel的该方法即可

#import <Foundation>#import "MovieModel.h"#import <UIKit>typedef void (^ReturnValueBlock) (id returnValue);typedef void (^ErrorCodeBlock) (id errorCode);@interface MovieViewModel : NSObject@property (nonatomic,copy) ReturnValueBlock returnBlock;@property (nonatomic,copy) ErrorCodeBlock errorBlock;//获取电影数据- (void)getMovieData;//跳转到电影详情页- (void)movieDetailWithPublicModel: (MovieModel *)movieModel WithViewController: (UIViewController *)superController;@end#import "MovieViewModel.h"#import "NetworkService.h"#import "MovieModel.h"#import "MovieViewController.h"@implementation MovieViewModel- (void)getMovieData{    [NetworkService requestWithURL:@"/v2/movie/coming_soon" params:nil success:^(id result) {        NSLog(@"%@",result);        NSArray *subjects = result[@"subjects"];        NSMutableArray *modelArr = [NSMutableArray arrayWithCapacity:subjects.count];        for (NSDictionary *subject in subjects) {            MovieModel *model = [[MovieModel alloc] init];            model.movieName = subject[@"title"];            model.year = subject[@"year"];            NSString *urlStr = subject[@"images"][@"medium"];            model.imageUrl = [NSURL URLWithString:urlStr];            model.detailUrl = subject[@"alt"];            [modelArr addObject:model];        }        _returnBlock(modelArr);    } failure:^(NSError *error) {         NSLog(@"%@",error);        _errorBlock(error);    }];}- (void)movieDetailWithPublicModel: (MovieModel *)movieModel WithViewController: (UIViewController *)superController{    MovieViewController *movieVC = [[MovieViewController alloc] init];    movieVC.url = movieModel.detailUrl;    [superController.navigationController pushViewController:movieVC animated:YES];}@end