ReactiveCocoa学习

ReactiveCocoa是一个将函数响应式编程范例带入Objective-C的开源库.

记录一下学习的过程。

环境搭建

通过CocoaPods导入ReactiveCocoa 编辑pod文件

use_frameworks!  
pod "ReactiveCocoa", "~> 4.1.0"  

 导入成功后即可使用

基本使用：

• 监听按钮事件

[[btn rac_signalForControlEvents:UIControlEventTouchUpInside] subscribeNext:^(id x) {
        NSLog(@"点击按钮");
    }];

• 监听方法调用

   [[self rac_signalForSelector:@selector(touchBtn:)] subscribeNext:^(id x) {
          NSLog(@"监听selector");
      }];
  

• 文本信号

   [_tf.rac_textSignal subscribeNext:^(id x) {
          _lbl.text = x;
      }];
  

• 宏定义使用

  RAC(_lbl, text) = _tv.rac_textSignal;
  
      //KVO
      [RACObserve(_lbl, text) subscribeNext:^(id x) {
          NSLog(@"%@", x);
      }];
  
      //元组
      RACTuple *tuple = RACTuplePack(@3, @4);
  
      RACTupleUnpack(NSString *key, NSString *value) = tuple;
  
      NSLog(@"%@ %@", key, value);
  

• 网络请求

  NSURLSessionConfiguration *configuration = [NSURLSessionConfiguration defaultSessionConfiguration];
  
      NSURLSession *session = [NSURLSession sessionWithConfiguration:configuration delegate:self delegateQueue:[NSOperationQueue mainQueue]];
  
      NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:@"http://www.wukongcoo1.com/content/images/2016/04/----3.gif"]];
  
      RACSignal *requestSignal = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
  
          NSURLSessionDataTask *task = [session dataTaskWithRequest:request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
  
              [subscriber sendNext:data];
              [subscriber sendCompleted];
  
          }];
  
          [task resume];
  
          return nil;
  
      }];
  
      [requestSignal subscribeNext:^(id x) {
          NSLog(@"请求到了 %@", x);
      }];
  

　　接下来介绍冷信号、热信号

　　

　冷信号

　　冷信号总结起来就是：信号源会对每一个订阅者发送完整的消息。 

　　

RACSignal *coldSignal = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {

        [subscriber sendNext:@1];
        [subscriber sendNext:@2];
        [subscriber sendNext:@3];

        return nil;

    }];

    [[RACScheduler mainThreadScheduler] afterDelay:0.1 schedule:^{

        [coldSignal subscribeNext:^(id x) {
            NSLog(@"subscribor 1 receive %@", x);
        }];
    }];


    [[RACScheduler mainThreadScheduler] afterDelay:1 schedule:^{

        [coldSignal subscribeNext:^(id x) {
            NSLog(@"subscribor 2 receive %@", x);
        }];
    }];

热信号

而热信号呢，信号源只会对订阅者发送订阅之后的消息

RACMulticastConnection *connection = [[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {  
        [[RACScheduler mainThreadScheduler] afterDelay:1 schedule:^{
            [subscriber sendNext:@1];
        }];

        [[RACScheduler mainThreadScheduler] afterDelay:2 schedule:^{
            [subscriber sendNext:@2];
        }];

        [[RACScheduler mainThreadScheduler] afterDelay:3 schedule:^{
            [subscriber sendNext:@3];
        }];

        [[RACScheduler mainThreadScheduler] afterDelay:4 schedule:^{
            [subscriber sendCompleted];
        }];
        return nil;
    }] publish];
    [connection connect];

    RACSignal *signal = connection.signal;

    NSLog(@"Signal was created.");
    [[RACScheduler mainThreadScheduler] afterDelay:1.1 schedule:^{
        [signal subscribeNext:^(id x) {
            NSLog(@"Subscriber 1 recveive: %@", x);
        }];
    }];

    [[RACScheduler mainThreadScheduler] afterDelay:2.1 schedule:^{
        [signal subscribeNext:^(id x) {
            NSLog(@"Subscriber 2 recveive: %@", x);
        }];
    }];

Map 与 FlattenMap

• Map

map的作用是对心法要发送的消息进行处理

RACSignal *signal = [[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {

        [subscriber sendNext:@3];

        return nil;

    }] map:^id(id value) {
        return [NSString stringWithFormat:@"map:%@", value];
    }];


    [signal subscribeNext:^(id x) {
        NSLog(@"%@", x);
    }];

• FlattenMap

FlattenMap的作用是对原有的信号进行订阅，从而生成新的信号，同时可以修改信号中的消息

[[[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {

        [subscriber sendNext:@3];

        return nil;

    }] flattenMap:^RACStream *(id value) {
        return [RACReturnSignal return:[NSString stringWithFormat:@"输出:%@",value]];
    }] subscribeNext:^(id x) {
        NSLog(@"%@", x);
    }];

实践

进行输入验证

RACSignal *canLoginSignal = [RACSignal combineLatest:@[  
                               _usernameLabel.rac_textSignal,
                               _pwdLabel.rac_textSignal]
                            reduce:^(NSString *username, NSString *password){
                                    NSLog(@"%@", username);
                                   return @(username.length > 5 && password.length > 5);
                               }];

    RAC(self.loginBtn, enabled) = canLoginSignal;

效果：

这里有demo的链接

参考资料

http://nshipster.cn/reactivecocoa/ 
http://tech.meituan.com/tag/ReactiveCocoa 
http://www.jianshu.com/p/87ef6720a096