The zdreactivecocoademo from ycace

##1. RAC简介

Github开源的一个应用于 iOS 和 OS X 开发的框架，兼具函数式编程和响应式编程的特性。

Mattt Thompson 大神 : 开启了一个新Objective-C纪元

解决问题： 传统iOS开发，消息传递、回调机制复杂等问题，使之清晰化，条理化

**Github主页： ** https://github.com/ReactiveCocoa/ReactiveCocoa

体积庞大： https://github.com/ReactiveCocoa/ReactiveCocoa/tree/master/ReactiveCocoa/Objective-C

用法： https://github.com/ReactiveCocoa/ReactiveCocoa/tree/master/Documentation/Legacy

最经典的示例：登录/注销需求：用户名、密码的长度均大于0，且当前尚未登录，登录按钮才可以点击（需要实时性地控制登录按钮是否可用的状态！）

可以打印任何东西的宏：https://github.com/DeveloperLx/LxDBAnything)

##最常用的函数： target-action：

文本框事件：

	UITextField * textField = [[UITextField alloc]init];
    textField.backgroundColor = [UIColor cyanColor];
    [self.view addSubview:textField];

    @weakify(self); //  __weak __typeof__(self) self_weak_ = self;
    
    [textField mas_makeConstraints:^(MASConstraintMaker *make) {
        
        @strongify(self); //  __strong __typeof__(self) self = self_weak_;
        make.size.mas_equalTo(CGSizeMake(180, 40));
        make.center.equalTo(self.view);
    }];
    
    [textField addTarget:self action:@selector(textChanged:) forControlEvents:UIControlEventEditingChanged];

	- (void)textChanged:(UITextField *)textField
	{
	    LxDBAnyVar(textField);
	}



    [[textField rac_signalForControlEvents:UIControlEventEditingChanged]
    subscribeNext:^(id x) {
        LxDBAnyVar(x);
    }];

    [textField.rac_textSignal subscribeNext:^(id x) {
        LxDBAnyVar(x);
    }];
    
	Tip: id x -> NSString * text

手势：

	self.view.userInteractionEnabled = YES;
    
    UITapGestureRecognizer * tap = [[UITapGestureRecognizer alloc]init];
    [[tap rac_gestureSignal] subscribeNext:^(UITapGestureRecognizer * tap) {
        LxDBAnyVar(tap);
    }];
    [self.view addGestureRecognizer:tap];

通知：(最简单)

	// 不需要removeObserver
	// 不要忘记添加takeUntil: 否则会出现observer未移除导致的内存泄露
	[[[[NSNotificationCenter defaultCenter] rac_addObserverForName:UIApplicationDidEnterBackgroundNotification object:nil] takeUntil:self.rac_willDeallocSignal] subscribeNext:^(NSNotification * notification) {
        LxDBAnyVar(notification);
    }];

定时器：

	// 常用两种：
	//1. 延迟某个时间后再做某件事

	[[RACScheduler mainThreadScheduler]afterDelay:2 schedule:^{
        LxPrintAnything(rac);
    }];

    //2. 每个一定长度时间做一件事

    [[RACSignal interval:1 onScheduler:[RACScheduler mainThreadScheduler]] subscribeNext:^(NSDate * date) {
        LxDBAnyVar(date);
    }];

代理：(有局限，只能取代没有返回值的代理方法)

    UIAlertView * alertView = [[UIAlertView alloc]initWithTitle:@"RAC" message:@"ReactiveCocoa" delegate:self cancelButtonTitle:@"Cancel" otherButtonTitles:@"Ensure", nil];
    [[self rac_signalForSelector:@selector(alertView:clickedButtonAtIndex:) fromProtocol:@protocol(UIAlertViewDelegate)] subscribeNext:^(RACTuple * tuple) {
        LxDBAnyVar(tuple);
        
        LxDBAnyVar(tuple.first);
        LxDBAnyVar(tuple.second);
        LxDBAnyVar(tuple.third);
    }];
    [alertView show];

    //更简单的方式：
    [[alertView rac_buttonClickedSignal] subscribeNext:^(id x) {
        LxDBAnyVar(x);
    }];

KVO:

	UIScrollView * scrollView = [[UIScrollView alloc] init];
    scrollView.delegate = (id<UIScrollViewDelegate>)self;
    [self.view addSubview:scrollView];
    
    UIView * scrollViewContentView = [[UIView alloc] init];
    scrollViewContentView.backgroundColor = [UIColor yellowColor];
    [scrollView addSubview:scrollViewContentView];
    
    @weakify(self);
    
    [scrollView mas_makeConstraints:^(MASConstraintMaker *make) {
        @strongify(self);
          make.edges.equalTo(self.view).insets(UIEdgeInsetsMake(80, 80, 80, 80));
    }];
    
    [scrollViewContentView mas_makeConstraints:^(MASConstraintMaker *make) {
        
        @strongify(self);
        make.edges.equalTo(scrollView);
        make.size.mas_equalTo(CGSizeMake(CGRectGetWidth(self.view.frame), CGRectGetHeight(self.view.frame)));
    }];
    
    [RACObserve(scrollView, contentOffset) subscribeNext:^(id x) {
        LxDBAnyVar(x);
    }];

    //（好处：写法简单，keypath有代码提示）

##进阶：

####1.创建信号 & 激活信号 & 废弃信号：

    - (RACSignal *)loginSignal
    {
        return [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
            
            RACDisposable * schedulerDisposable = [[RACScheduler mainThreadScheduler] afterDelay:2 schedule:^{
               
                if (arc4random()%10 > 1) {
                    
                    [subscriber sendNext:@"Login response"];
                    [subscriber sendCompleted];
                }
                else {
                    
                    [subscriber sendError:[NSError errorWithDomain:@"LOGIN_ERROR_DOMAIN" code:444 userInfo:@{}]];
                }
            }];
            
            return [RACDisposable disposableWithBlock:^{
                
                [schedulerDisposable dispose];
            }];
        }];
    }

** 经典示例：**

    - (RACSignal *)rac_addObserverForName:(NSString *)notificationName object:(id)object {
        @unsafeify(object);
        return [[RACSignal createSignal:^(id<RACSubscriber> subscriber) {
            @strongify(object);
            id observer = [self addObserverForName:notificationName object:object queue:nil usingBlock:^(NSNotification *note) {
                [subscriber sendNext:note];
            }];

            return [RACDisposable disposableWithBlock:^{
                [self removeObserver:observer];
            }];
        }] setNameWithFormat:@"-rac_addObserverForName: %@ object: <%@: %p>", notificationName, [object class], object];
    }

####2.信号的处理：

map： filter: delay: startWith: timeout:

    [[[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
       
        [[RACScheduler mainThreadScheduler]afterDelay:3 schedule:^{
           
            [subscriber sendNext:@"rac"];
            [subscriber sendCompleted];
        }];
        
        return nil;
    }] timeout:2 onScheduler:[RACScheduler mainThreadScheduler]]
    subscribeNext:^(id x) {
      
        LxDBAnyVar(x);
    } error:^(NSError *error) {
        
        LxDBAnyVar(error);
    } completed:^{
        
        LxPrintAnything(completed);
    }];

take: skip: takeLast: takeUntil: takeWhileBlock: skipWhileBlock: skipUntilBlock:

throttle: (限流，即时搜索优化) distinctUntilChanged: ignore: switchToLatest:

    UITextField * textField = [[UITextField alloc]init];
    textField.backgroundColor = [UIColor cyanColor];
    [self.view addSubview:textField];
    
    @weakify(self); 
    
    [textField mas_makeConstraints:^(MASConstraintMaker *make) {
        
        @strongify(self);  
        make.size.mas_equalTo(CGSizeMake(180, 40));
        make.center.equalTo(self.view);
    }];
    
    [[[[[[textField.rac_textSignal throttle:0.3] distinctUntilChanged]ignore:@""] map:^id(id value) {
        
        return [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
           
            //  network request
            [subscriber sendNext:value];
            [subscriber sendCompleted];
            
            return [RACDisposable disposableWithBlock:^{
                
                //  cancel request
            }];
        }];
    }] switchToLatest] subscribeNext:^(id x) {
      
        LxDBAnyVar(x);
    }];

repeat:

		[[[[[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
       
	        [subscriber sendNext:@"rac"];
	        [subscriber sendCompleted];
	        
	        return nil;
	    }]delay:1]repeat]take:3] subscribeNext:^(id x) {
	       
	        LxDBAnyVar(x);
	    } completed:^{
	      
	        LxPrintAnything(completed);
	    }];

merge:

	RACSignal * signalA = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
      
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
            LxPrintAnything(a);
            [subscriber sendNext:@"a"];
            [subscriber sendCompleted];
        });
        
        return nil;
    }];
    
    RACSignal * signalB = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
        
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
            LxPrintAnything(b);
            [subscriber sendNext:@"b"];
            [subscriber sendCompleted];
        });
        
        return nil;
    }];
    
    [[RACSignal merge:@[signalA, signalB]] subscribeNext:^(id x) {
       
        LxDBAnyVar(x);
    }];

combineLatest:reduce:

concat: （连接: 一个请求完成后，再启动另一个）

	RACSignal * signalA = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
      
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(3 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
            LxPrintAnything(a);
            [subscriber sendNext:@"a"];
            [subscriber sendCompleted];
        });
        
        return nil;
    }];
    
    RACSignal * signalB = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
        
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
            LxPrintAnything(b);
            [subscriber sendNext:@"b"];
            [subscriber sendCompleted];
        });
        
        return nil;
    }];
    
    [[signalA concat:signalB] subscribeNext:^(id x) {
       
        LxDBAnyVar(x);
    }];

zipWith: （zip是成对出现的,二者都发送完毕或者无法凑成一对时,终止.意味着如果是一个流的第N个元素，一定要等到另外一个流第N值也收到才会一起组合发出。）

	RACSignal * signalA = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
      
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(3 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
            LxPrintAnything(a);
            [subscriber sendNext:@"a"];
            [subscriber sendCompleted];
        });
        
        return nil;
    }];
    
    RACSignal * signalB = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
        
        dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
            LxPrintAnything(b);
            [subscriber sendNext:@"b"];
            [subscriber sendCompleted];
        });
        
        return nil;
    }];
    
    [[signalA zipWith:signalB] subscribeNext:^(id x) {
       
        LxDBAnyVar(x);
    }];

RAC(<#TARGET, ...#>) 宏:

button setBackgroundColor:forState:

	UIButton * button = [UIButton buttonWithType:UIButtonTypeCustom];
    [self.view addSubview:button];
    
    @weakify(self);
    
    [button mas_makeConstraints:^(MASConstraintMaker *make) {
        
        @strongify(self);
        make.size.mas_equalTo(CGSizeMake(180, 40));
        make.center.equalTo(self.view);
    }];
    
    RAC(button, backgroundColor) = [RACObserve(button, selected) map:^UIColor *(NSNumber * selected) {
        
        return [selected boolValue] ? [UIColor redColor] : [UIColor greenColor];
    }];
    
    [[button rac_signalForControlEvents:UIControlEventTouchUpInside] subscribeNext:^(UIButton * btn) {
       
        btn.selected = !btn.selected;
    }];

用最少的代码写一个秒表：

	RAC(label, text) = [[RACSignal interval:1 onScheduler:[RACScheduler mainThreadScheduler]] map:^NSString *(NSDate * date) {
       
        return date.description;
    }];

####几张图对函数的说明

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