前一段项目中用到了ReactiveCocoa.今天做一下简单的总结,当然项目还在不断尝试ReactiveCocoa的最佳实践,希望自己还会有后续的文章 :)
<h4>MVC</h4>
一切要从我们熟悉的MVC架构开始,这个被戏称为Massive View Controller(臃肿的视图控制器)的软件架构如下:
MVC架构
- Model:Encapsulate the data specific to an application and define the logic and computation that manipulate and process that data.
- View:Is an object in an application that users can see.
- Controller: Acts as an intermediary between one or more of an application’s view objects and one or more of its model objects.
From:Cocoa Core Competencies
简单来说Model用于程序的基本数据对象,View用于UI控件展示,Controller用于粘合View和Model,将Model里的数据内容展示到UI上.
CS193p上有幅图来表示MVC之间的关系及如何来进行通讯:
MVC
- Model层无法与View层进行通信的.
- Controller能直接读写调用Model,Model通过Notification&KVO来和Controller进行通信
- Controller可以直接和View层通信,通过outlet控制View上的控件,View可以通过action来射向Controller里的target来告诉Controller View中某个控件被点击等的操作.Controller还可以通过Protocol(delegate,datasource等)来对View进行控制.
MVC在iOS开发中被广泛应用,然而慢慢你会发现他有些弊端,那就是大量的处理逻辑都塞进了ViewController里面，会使其代码行数变得不可控,于是就有人引入了MVVM.
<h5>MVVM</h5>
引用ReactiveCocoa and MVVM,an Introduction中的一幅图来说明MVVM与MVC之间的联系:
MVVM & MVC
简单来说ViewModel是将Controller里面的逻辑代码分离出来,使Controller只用于将处理好的数据与View对应起来.这就会产生一个问题:ViewModel如何与Controller进行通信呢？想到的最简单的就是delegate.然而笨重写法会使代码变得难看,而拯救我们的super man就是ReactiveCocoa.
<h6>ReactiveCocoa的简单使用</h6>
- 对值的监听
[self.usernameTextField.rac_textSignal subscribeNext:^(id x) {
NSLog(@"username = %@", x);
}];
- 对值的过滤
[[self.usernameTextField.rac_textSignal
filter:^BOOL(NSString *text) {
return text.length > 5;
}]
subscribeNext:^(id x) {
NSLog(@"filter x = %@", x);
}];
- 对值的处理转换
[[[self.usernameTextField.rac_textSignal map:^id(NSString *text) {
return @(text.length);
}]
filter:^BOOL(NSNumber *length) {
return [length integerValue] > 5;
}]
subscribeNext:^(id x) {
NSLog(@"username x = %@", x);
}];
RACSignal *validUsernameSignal = [self.usernameTextField.rac_textSignal
map:^id(NSString *text) {
return @([self isValidUsername:text]);
}];
- (BOOL)isValidUsername:(NSString *)username {
return username.length > 5;
}
- 对值的监听
RAC(self.passwordTextfield, backgroundColor) = [validPasswordSignal map:^id(NSNumber *passwordValid) {
return [passwordValid boolValue] ? [UIColor clearColor] : [UIColor yellowColor];
}];
- 信号的融合
RACSignal *validUsernameSignal = [self.usernameTextField.rac_textSignal
map:^id(NSString *text) {
return @([self isValidUsername:text]);
}];
RACSignal *validPasswordSignal = [self.passwordTextfield.rac_textSignal
map:^id(NSString *text) {
return @([self isValidPassword:text]);
}];
RACSignal *signUpActiveSignal = [RACSignal combineLatest:@[validUsernameSignal, validPasswordSignal]
reduce:^id(NSNumber *usernameValid, NSNumber *passwordValid){
return @([usernameValid boolValue] && [passwordValid boolValue]);
}];
[signUpActiveSignal subscribeNext:^(NSNumber *signupActive) {
self.loginButton.enabled = [signupActive boolValue];
}];
- 对事件的监听
[[[self.loginButton rac_signalForControlEvents:UIControlEventTouchUpInside]
map:^id(id value) {
return [self loginSignal];
}]
subscribeNext:^(id x) {
NSLog(@"login result: %@", x);
}];
- (RACSignal *)loginSignal {
return [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
[self.loginService loginWithUsername:self.usernameTextField.text password:self.passwordTextfield.text complete:^(BOOL success) {
[subscriber sendNext:@(success)];
[subscriber sendCompleted];
}];
return nil;
}];
}
Demo地址
<h3>参考</h3>
