标签（空格分隔）： RAC FRP 函数式编程 响应式编程
本文内容仅适用于
关于函数响应式编程（FRP），可以参考
Streams of values over time
ReactiveCocoa repo上最简单的一句话对FRP做了本质的描述，而repo本身提供的是APIs of composing and transforming streams of values，而Streams of values的抽象在ReactiveCocoa中应该是RACStream，而composing and transforming是本文的重点。
先解释ReactiveCocoa中的两个基本概念
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信号（Signal） a signal is a steam of values，signals can be transformed, combined,etc.
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订阅者（Subscriber） a subscriber subscribes to a signal. RAC lets blocks,objects, and properties subscribe to signals
filter
RACSignal *signal = [@[ @1, @2, @3 ] rac_sequence].signal; signal = [signal filter:^BOOL(NSNumber *value) { return value.integerValue % 2;}];[signal subscribeNext:^(NSNumber *value) { NSLog(@"%@", value);}];复制代码 map
RACSignal *signal = [@[ @1, @2, @3 ] rac_sequence].signal; signal = [signal map:^id(NSNumber *value) { return @(value.integerValue * 2); }]; [signal subscribeNext:^(NSNumber *value) { NSLog(@"%@", value); }];复制代码 merge
RACSignal *signal1 = [@[ @1, @2 ] rac_sequence].signal;RACSignal *signal2 = [@[ @4, @5 ] rac_sequence].signal;[[signal1 merge:signal2] subscribeNext:^(NSNumber *value) { NSLog(@"%@", value);}];复制代码 combineLatest
RACSignal *signal1 = [@[ @1, @2 ] rac_sequence].signal; RACSignal *signal2 = [@[ @3, @4 ] rac_sequence].signal; [[signal1 combineLatestWith:signal2] subscribeNext:^(RACTuple *value) { NSLog(@"%@", value); }];复制代码 combineLatest & reduce
RACSignal *signal1 = [@[ @1, @2 ] rac_sequence].signal; RACSignal *signal2 = [@[ @3, @4 ] rac_sequence].signal; [[[signal1 combineLatestWith:signal2] reduceEach:^id(NSNumber *v1, NSNumber *v2) { return @(v1.integerValue * v2.integerValue); }] subscribeNext:^(RACTuple *value) { NSLog(@"%@", value); }];复制代码 flatten
RACSignal *signal1 = [@[ @1, @2 ] rac_sequence].signal;RACSignal *signal2 = [RACSignal return:signal1];[[signal2 flatten] subscribeNext:^(NSNumber *value) { NSLog(@"%@", value);}];复制代码 flattenMap
RACSignal *signal = [@[ @1, @2 ] rac_sequence].signal;[[signal flattenMap:^RACStream *(NSNumber *value) { return [RACSignal return:@(value.integerValue * 2)];}] subscribeNext:^(NSNumber *value) { NSLog(@"%@", value);}];复制代码 not replay
RACSubject *letters = [RACSubject subject];RACSignal *signal = letters;[signal subscribeNext:^(id x) { NSLog(@"S1: %@", x);}];[letters sendNext:@"A"];[signal subscribeNext:^(id x) { NSLog(@"S2: %@", x);}];[letters sendNext:@"B"];[letters sendNext:@"C"];复制代码 replay
RACSubject *letters = [RACReplaySubject subject];RACSignal *signal = letters;[signal subscribeNext:^(id x) { NSLog(@"S1: %@", x);}];[letters sendNext:@"A"];[signal subscribeNext:^(id x) { NSLog(@"S2: %@", x);}];[letters sendNext:@"B"];[signal subscribeNext:^(id x) { NSLog(@"S3: %@", x);}];[letters sendNext:@"C"];复制代码 replayLast
RACSubject *letters = [RACSubject subject];RACSignal *signal = [letters replayLast];[signal subscribeNext:^(id x) { NSLog(@"S1: %@", x);}];[letters sendNext:@"A"];[signal subscribeNext:^(id x) { NSLog(@"S2: %@", x);}];[letters sendNext:@"B"];[signal subscribeNext:^(id x) { NSLog(@"S3: %@", x);}];[letters sendNext:@"C"];复制代码 replayLazily
RACSubject *letters = [RACSubject subject];RACSignal *signal = [letters replayLazily];[letters sendNext:@"A"];[signal subscribeNext:^(id x) { NSLog(@"S1: %@", x);}];[letters sendNext:@"B"];[signal subscribeNext:^(id x) { NSLog(@"S2: %@", x);}];[letters sendNext:@"C"];[signal subscribeNext:^(id x) { NSLog(@"S3: %@", x);}];[letters sendNext:@"D"];复制代码 zip
RACSubject *letters = [RACSubject subject];RACSubject *numbers = [RACSubject subject];RACSignal *combined = [RACSignal zip:@[ letters, numbers ] reduce:^(NSString *letter, NSString *number) { return [letter stringByAppendingString:number]; }];// Outputs: A1 B2 C3[combined subscribeNext:^(id x) { NSLog(@"%@", x);}];[letters sendNext:@"A"];[letters sendNext:@"B"];[letters sendNext:@"C"];[numbers sendNext:@"1"];[numbers sendNext:@"2"];[numbers sendNext:@"3"];复制代码 完整的源码可以在这里找到
"-g"选项 : 查看日志缓冲区信息;"-b"选项 : 加载一个日志缓冲区, 默认是 main, 下面详解;"-B"选项 : 以二进制形式输出日志;复制代码
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