MVC设计模式

MVC的核心是非常简单又非常好的设计理念

MVC有3部分组成

1. Model－数据模型

2. View－用户交互界面

3. Controller－控制器存在于Model和View之间

MVVM 一个更好的世界

MVVM的模型标准是 Model-View-ViewModel

MVVM与MVC的不同

在MVVM模式中View Model分装数据与属性，view可以绑定他，他可以展示任何的逻辑与动作。

例如：你需要修改一个按钮的title为你在View Model中申明的一个属性，你可以将View Model的属性绑定到按钮上。

我们不必关心UI测试

在标准控件上我们不必关心UI测试，我们只是在上边绑定View Model。

我们可以容易的修改UI

因为UI是绑定到视图模型,这意味着你应该能够交换组件仅仅是通过将属性绑定到视图模型和UI应该与以前一样工作。这也应该使UI设计人员更容易尝试着不同的view在你的应用程序中

ViewModel到底是什么？

看一个简单的使用ViewModel的例子

ViewModel实例

#import

@interface CDWPlayerViewModel : NSObject

@property(nonatomic, retain) NSString *playerName;

@property(nonatomic, assign) double points;

@property(nonatomic, assign) double stepAmount;

@property(nonatomic, assign) double maxPoints;

@property(nonatomic, assign) double minPoints;

@property(nonatomic, readonly) NSUInteger maxPointUpdates;

-(IBAction)resetToDefaults:(id)sender;

-(IBAction)uploadData:(id)sender;

-(RACSignal *)forbiddenNameSignal;

-(RACSignal *)modelIsValidSignal;

@end

ViewController

//

//ViewController.m

//racTestTwo

//

//Created by HEcom on 16/9/20.

//Copyright © 2016年Jorgon. All rights reserved.

//

#import"ViewController.h"

#import

#import"PlayerViewModle.h"

#import

@interfaceViewController()

@property(weak,nonatomic)IBOutletUITextField*iPlayerName;

@property(weak,nonatomic)IBOutletUIStepper*iStepper;

@property(nonatomic,strong)PlayerViewModle*iViewModel;

@property(weak,nonatomic)IBOutletUIButton*iUploadButton;

@property(weak,nonatomic)IBOutletUILabel*iScoreField;

@property(weak,nonatomic)IBOutletUILabel*iStepperValue;

@property(nonatomic,assign)NSUIntegerscoreUpdates;

@end

staticNSIntegerconstkMaxUploads =5;

@implementationViewController

- (void)viewDidLoad {

[superviewDidLoad];

// Do any additional setup after loading the view, typically from a nib.

self.iViewModel= [[PlayerViewModlealloc]init];

@weakify(self);

//Start binding our properties

RAC(self.iPlayerName,text) = [RACObserve(self.iViewModel, playerName)distinctUntilChanged];

[[self.iPlayerName.rac_textSignaldistinctUntilChanged]subscribeNext:^(idx) {

//this creates a reference to self that when used with @weakify(self);

//makes sure self isn't retained

@strongify(self);

self.iViewModel.playerName= x;

}];

//the score property is a double, RC gives us updates as NSNumber which we just call

//stringValue on and bind that to the scorefield text

RAC(self.iScoreField,text) = [RACObserve(self.iViewModel,points)map:^id(NSNumber*value) {

return[valuestringValue];

}];

//Setup bind the steppers values

self.iViewModel.points=self.iStepper.value;

RAC(self.iStepper,stepValue) =RACObserve(self.iViewModel,stepAmount);

RAC(self.iStepper,maximumValue) =RACObserve(self.iViewModel,maxPoints);

RAC(self.iStepper,minimumValue) =RACObserve(self.iViewModel,minPoints);

//bind the hidden field to a signal keeping track if

//we've updated less than a certain number times as the view model specifies

RAC(self.iStepper,hidden) = [RACObserve(self,scoreUpdates)map:^id(NSNumber*x) {

@strongify(self);

return@(x.intValue>=self.iViewModel.maxPointUpdates);

}];

//this signal should only trigger if we have "bad words" in our name

[self.iViewModel.forbiddenNameSignalsubscribeNext:^(NSString*name) {

@strongify(self);

UIAlertView*alert = [[UIAlertViewalloc]initWithTitle:@"Forbidden Name!"

message:[NSStringstringWithFormat:@"The name %@ has been forbidden!",name]

delegate:nil

cancelButtonTitle:@"Ok"

otherButtonTitles:nil];

[alertshow];

self.iViewModel.playerName=@"";

}];

//let the upload(save) button only be enabled when the view model says its valid

RAC(self.iUploadButton,enabled) =self.iViewModel.modelIsValidSignal;

//set the control action for our button to be the ViewModels action method

[self.iUploadButtonaddTarget:self.iViewModel

action:@selector(uploadData:)

forControlEvents:UIControlEventTouchUpInside];

//we can subscribe to the same thing in multiple locations

//here we skip the first 4 signals and take only 1 update

//and then disable/hide certain UI elements as our app

//only allows 5 updates

[[[[self.iUploadButton rac_signalForControlEvents:UIControlEventTouchUpInside]

skip:(kMaxUploads -1)] take:1] subscribeNext:^(idx) {

@strongify(self);

self.iPlayerName.enabled =NO;

self.iStepper.hidden =YES;

self.iUploadButton.hidden =YES;

}];

}

- (void)didReceiveMemoryWarning {

[superdidReceiveMemoryWarning];

// Dispose of any resources that can be recreated.

}

@end

本页代码链接

参考文档：http://cocoasamurai.blogspot.jp/2013/03/basic-mvvm-with-reactivecocoa.html