架构模式MVC,MVP, MVVM

MVC

MVC架构模式: 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。

用户操作View, 在Controller层完成业务逻辑处理, 更新Model层, 将数据显示在View层.

• Model层

@interface Person : NSObject
@property (nonatomic, readonly) NSString *firstName;
@property (nonatomic, readonly) NSString *lastName;

- (instancetype)initWithFirstName:(NSString *)firstName lastName:(NSString *)lastName;

@end

@implementation Person

- (instancetype)initWithFirstName:(NSString *)firstName lastName:(NSString *)lastName {
    if ([super init]) {
        _firstName = firstName;
        _lastName = lastName;
    }
    return self;
}
@end

• View层

@interface TestView : UIView

@property (nonatomic, strong) UILabel *nameLabel;

@end

@implementation TestView

- (instancetype)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        _nameLabel = [[UILabel alloc] initWithFrame:self.bounds];
        _nameLabel.textAlignment = NSTextAlignmentCenter;
        [self addSubview:_nameLabel];
    }
    return self;
}
@end

• Controller层

@interface ViewController ()

@property (nonatomic, strong) Person *personModel;
@property (nonatomic, strong) TestView *testView;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    [self setupViews];

    if (self.personModel.firstName.length > 0) {
        self.testView.nameLabel.text = self.personModel.firstName;
    } else {
        self.testView.nameLabel.text = self.personModel.lastName;
    }
}

- (void)setupViews {
    self.personModel = [[Person alloc] initWithFirstName:@"" lastName:@"XXX"];
    self.testView = [[TestView alloc] initWithFrame:CGRectMake(100, 100, CGRectGetWidth(self.view.bounds)-200, 50)];
    [self.view addSubview:self.testView];
}

@end

MVP

MVP架构模式: Model-View-Presenter是MVC的改良模式，由IBM的子公司Taligent提出。和MVC的相同之处在于：Controller/Presenter负责业务逻辑，Model管理数据，View负责显示只不过是将 Controller 改名为 Presenter，同时改变了通信方向。
View 与 Model 不通信，都通过 Presenter 传递。Presenter完全把Model和View进行了分离，主要的程序逻辑在Presenter里实现。

• Model层

@interface Person : NSObject

@property (nonatomic, readonly) NSString *firstName;
@property (nonatomic, readonly) NSString *lastName;

- (instancetype)initWithFirstName:(NSString *)firstName lastName:(NSString *)lastName;

@end

@implementation Person

- (instancetype)initWithFirstName:(NSString *)firstName lastName:(NSString *)lastName {
    if (self = [super init]) {
        _firstName = firstName;
        _lastName = lastName;
    }
    return self;
}

@end

• View层

@interface TestView : UIView

@property (nonatomic, strong) UILabel *nameLabel;

@end

@implementation TestView

- (instancetype)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        _nameLabel = [[UILabel alloc] initWithFrame:self.bounds];
        _nameLabel.textAlignment = NSTextAlignmentCenter;
        [self addSubview:_nameLabel];
    }
    return self;
}
@end

• Presenter层

@protocol PersonViewProtocol

- (void)setNameText:(NSString *)nameText;

@end

@interface Presenter : NSObject

- (void)attachView:(id )view;

- (void)fetchData;

@end


@interface Presenter()

@property (nonatomic, strong) Person *person;
@property (nonatomic, weak) id attachView;

@end

@implementation Presenter

- (void)attachView:(id)view {
    self.attachView = view;
}

- (void)fetchData {
    self.person = [[Person alloc] initWithFirstName:@"AAA" lastName:@"BB"];
    if (self.person.firstName.length > 0) {
        [self.attachView setNameText:self.person.firstName];
    } else {
        [self.attachView setNameText:self.person.lastName];
    }
}

@end

• Controller

@interface ViewController ()

@property (nonatomic, strong) TestView *testView;
@property (nonatomic, strong) Presenter *presenter;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    [self setupViews];

    self.presenter = [Presenter new];
    [self.presenter attachView:self];
    [self.presenter fetchData];
}

- (void)setupViews {
    self.testView = [[TestView alloc] initWithFrame:CGRectMake(100, 100, CGRectGetWidth(self.view.bounds)-200, 50)];
    [self.view addSubview:self.testView];
}

#pragma PersonViewProtocol
- (void)setNameText:(NSString *)nameText {
    self.testView.nameLabel.text = nameText;
}

@end

MVVM

MVVM架构模式: Model-View-ViewModel是 M-V-VM 三部分组成，它本质上就是 MVC 的改进版. 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。然而，随着模块的迭代我们越来越发现 MVC 自身存在着很多不足。因此，MVVM 从其他应用而出，在 iOS 中从此我们完全将业务逻辑加以区分并使用这套思想。在 MVVM 中他的设计思路和 MVC 很像。它正式规范了视图和控制器紧耦合的性质，并引入新的组件 ViewModel。此外，它还有像监管版本的 MVP 那样的绑定功能，但这个绑定不是在 View 和 Model 之间而是在 View 和 ViewModel 之间。

• Model层

@interface Person : NSObject

@property (nonatomic, readonly) NSString *firstName;
@property (nonatomic, readonly) NSString *lastName;

- (instancetype)initWithFirstName:(NSString *)firstName lastName:(NSString *)lastName;

@end

@implementation Person

- (instancetype)initWithFirstName:(NSString *)firstName lastName:(NSString *)lastName {
    if (self = [super init]) {
        _firstName = firstName;
        _lastName = lastName;
    }
    return self;
}

@end

• View层

@interface TestView : UIView

@property (nonatomic, strong) UILabel *nameLabel;

@end

@implementation TestView

- (instancetype)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        _nameLabel = [[UILabel alloc] initWithFrame:self.bounds];
        _nameLabel.textAlignment = NSTextAlignmentCenter;
        [self addSubview:_nameLabel];
    }
    return self;
}

@end

• ViewModel层

@interface PersonViewModel : NSObject

@property (nonatomic, readonly) Person *person;
@property (nonatomic, readonly) NSString *nameText;

- (instancetype)initWithPerson:(Person *)person;

@end


@implementation PersonViewModel

- (instancetype)initWithPerson:(Person *)person {

    if (self = [super init]) {
        _person = person;
        if (_person.firstName.length > 0) {
            _nameText = _person.firstName;
        } else {
            _nameText = _person.lastName;
        }
    }
    return self;
}

@end

• Controller

@interface ViewController ()

@property (nonatomic, strong) TestView *testView;
@property (nonatomic, strong) PersonViewModel *viewModel;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    [self setupViews];

    self.testView.nameLabel.text = self.viewModel.nameText;
}

- (void)setupViews {
    Person *person = [[Person alloc] initWithFirstName:@"AAA" lastName:@"BB"];
    self.viewModel = [[PersonViewModel alloc] initWithPerson:person];
    self.testView = [[TestView alloc] initWithFrame:CGRectMake(100, 100, CGRectGetWidth(self.view.bounds)-200, 50)];
    [self.view addSubview:self.testView];
}

@end