前戏
我个人非常推崇ReactiveCocoa,它就像中国的太极,太极生两仪,两仪生四象,四象生八卦,八卦生万物。ReactiveCocoa是一个高度抽象的编程框架,它真的很抽象,初看你不知道它是要干嘛的,等你用上了之后,就发现,有了它你是想干嘛就干嘛,编码从未如此流畅。
在此我不会讲ReactiveCocoa的原理,因为不能讲明白的才叫抽象。我也不会提及相关概念。我只是让你看看我用着它是有多爽。
代码的四十八手
察值
你别动,你一动我就知道。
- @weakify(self);
- [RACObserve(self, value) subscribeNext:^(NSString* x) {
- @strongify(self);
- NSLog(@"你动了");
- }];
单边
你唱歌,我就跳舞。
textField的内容长度隐射成BOOL值,绑定到confirmButton的enable属性上面,当textField输入内容不为空的时候,confirmButton的enable = YES。
- RACSignal *signalA = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- [subscriber sendNext:@"唱歌"];
- [subscriber sendCompleted];
- return nil;
- }];
- RAC(self, value) = [signalA map:^id(NSString* value) {
- if ([value isEqualToString:@"唱歌"]) {
- return @"跳舞";
- }
- return @"";
- }];
双边
你向西,他就向东,他向左,你就向右。
- RACChannelTerminal *channelA = RACChannelTo(self, valueA);
- RACChannelTerminal *channelB = RACChannelTo(self, valueB);
- [[channelA map:^id(NSString *value) {
- if ([value isEqualToString:@"西"]) {
- return @"东";
- }
- return value;
- }] subscribe:channelB];
- [[channelB map:^id(NSString *value) {
- if ([value isEqualToString:@"左"]) {
- return @"右";
- }
- return value;
- }] subscribe:channelA];
- [[RACObserve(self, valueA) filter:^BOOL(id value) {
- return value ? YES : NO;
- }] subscribeNext:^(NSString* x) {
- NSLog(@"你向%@", x);
- }];
- [[RACObserve(self, valueB) filter:^BOOL(id value) {
- return value ? YES : NO;
- }] subscribeNext:^(NSString* x) {
- NSLog(@"他向%@", x);
- }];
- self.valueA = @"西";
- self.valueB = @"左";
- 2015-08-15 20:14:46.544 Test[2440:99901] 你向西
- 2015-08-15 20:14:46.544 Test[2440:99901] 他向东
- 2015-08-15 20:14:46.545 Test[2440:99901] 他向左
- 2015-08-15 20:14:46.545 Test[2440:99901] 你向右
代理
你是程序员,你帮我写个app吧。
- @protocol Programmer <NSObject>
- - (void)makeAnApp;
- @end
- RACSignal *ProgrammerSignal =
- [self rac_signalForSelector:@selector(makeAnApp)
- fromProtocol:@protocol(Programmer)];
- [ProgrammerSignal subscribeNext:^(RACTuple* x) {
- NSLog(@"花了一个月,app写好了");
- }];
- [self makeAnApp];
- 2015-08-15 20:46:45.720 Test[2817:114564] 花了一个月,app写好了
广播
知道你的频道,我就能听到你了。
- [[[NSNotificationCenter defaultCenter] rac_addObserverForName:@"代码之道频道" object:nil] subscribeNext:^(NSNotification* x) {
- NSLog(@"技巧:%@", x.userInfo[@"技巧"]);
- }];
- [[NSNotificationCenter defaultCenter] postNotificationName:@"代码之道频道" object:nil userInfo:@{@"技巧":@"用心写"}];
- 2015-08-15 20:41:15.786 Test[2734:111505] 技巧:用心写
连接
生活是一个故事接一个故事。
- RACSignal *signalA = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- [subscriber sendNext:@"我恋爱啦"];
- [subscriber sendCompleted];
- return nil;
- }];
- RACSignal *signalB = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- [subscriber sendNext:@"我结婚啦"];
- [subscriber sendCompleted];
- return nil;
- }];
- [[signalA concat:signalB] subscribeNext:^(id x) {
- NSLog(@"%@",x);
- }];
- 2015-08-15 12:19:46.707 Test[1845:64122] 我恋爱啦
- 2015-08-15 12:19:46.707 Test[1845:64122] 我结婚啦
合并
污水都应该流入污水处理厂被处理。
- RACSignal *signalA = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- [subscriber sendNext:@"纸厂污水"];
- return nil;
- }];
- RACSignal *signalB = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- [subscriber sendNext:@"电镀厂污水"];
- return nil;
- }];
- [[RACSignal merge:@[signalA, signalB]] subscribeNext:^(id x) {
- NSLog(@"处理%@",x);
- }];
- 2015-08-15 12:10:05.371 Test[1770:60147] 处理纸厂污水
- 2015-08-15 12:10:05.372 Test[1770:60147] 处理电镀厂污水
组合
你是红的,我是黄的,我们就是红黄的,你是白的,我没变,我们是白黄的。
- RACSignal *signalA = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- [subscriber sendNext:@"红"];
- [subscriber sendNext:@"白"];
- return nil;
- }];
- RACSignal *signalB = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- [subscriber sendNext:@"白"];
- return nil;
- }];
- [[RACSignal combineLatest:@[signalA, signalB]] subscribeNext:^(RACTuple* x) {
- RACTupleUnpack(NSString *stringA, NSString *stringB) = x;
- NSLog(@"我们是%@%@的", stringA, stringB);
- }];
- 2015-08-15 12:14:19.837 Test[1808:62042] 我们就是红黄的
- 2015-08-15 12:14:19.837 Test[1808:62042] 我们是白黄的
压缩
你是红的,我是黄的,我们就是红黄的,你是白的,我没变,哦,那就等我变了再说吧。
- RACSignal *signalA = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- [subscriber sendNext:@"红"];
- [subscriber sendNext:@"白"];
- return nil;
- }];
- RACSignal *signalB = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- [subscriber sendNext:@"白"];
- return nil;
- }];
- [[signalA zipWith:signalB] subscribeNext:^(RACTuple* x) {
- RACTupleUnpack(NSString *stringA, NSString *stringB) = x;
- NSLog(@"我们是%@%@的", stringA, stringB);
- }];
- 2015-08-15 20:34:24.274 Test[2660:108483] 我们是红白的
映射
我可以点石成金。
- RACSignal *signal = [[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- [subscriber sendNext:@"石"];
- return nil;
- }] map:^id(NSString* value) {
- if ([value isEqualToString:@"石"]) {
- return @"金";
- }
- return value;
- }];
- [signal subscribeNext:^(id x) {
- NSLog(@"%@", x);
- }];
- 2015-08-16 20:00:12.853 Test[740:15871] 金
归约
糖加水变成糖水。
- RACSignal *sugarSignal = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- [subscriber sendNext:@"糖"];
- return nil;
- }];
- RACSignal *waterSignal = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- [subscriber sendNext:@"水"];
- return nil;
- }];
- [[RACSignal combineLatest:@[sugarSignal, waterSignal] reduce:^id (NSString* sugar, NSString*water){
- return [sugar stringByAppendingString:water];
- }] subscribeNext:^(id x) {
- NSLog(@"%@", x);
- }];
- 2015-08-16 20:07:00.356 Test[807:19177] 糖水
过滤
未满十八岁,禁止进入。
- [[[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- [subscriber sendNext:@(15)];
- [subscriber sendNext:@(17)];
- [subscriber sendNext:@(21)];
- [subscriber sendNext:@(14)];
- [subscriber sendNext:@(30)];
- return nil;
- }] filter:^BOOL(NSNumber* value) {
- return value.integerValue >= 18;
- }] subscribeNext:^(id x) {
- NSLog(@"%@", x);
- }];
- 2015-08-16 20:11:20.071 Test[860:21214] 21
- 2015-08-16 20:11:20.071 Test[860:21214] 30
扁平
打蛋液,煎鸡蛋,上盘。
- [[[[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- NSLog(@"打蛋液");
- [subscriber sendNext:@"蛋液"];
- [subscriber sendCompleted];
- return nil;
- }] flattenMap:^RACStream *(NSString* value) {
- return [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- NSLog(@"把%@倒进锅里面煎",value);
- [subscriber sendNext:@"煎蛋"];
- [subscriber sendCompleted];
- return nil;
- }];
- }] flattenMap:^RACStream *(NSString* value) {
- return [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- NSLog(@"把%@装到盘里", value);
- [subscriber sendNext:@"上菜"];
- [subscriber sendCompleted];
- return nil;
- }];
- }] subscribeNext:^(id x) {
- NSLog(@"%@", x);
- }];
- 2015-08-16 20:39:34.786 Test[1226:34386] 打蛋液
- 2015-08-16 20:39:34.787 Test[1226:34386] 把蛋液倒进锅里面煎
- 2015-08-16 20:39:34.787 Test[1226:34386] 把煎蛋装到盘里
- 2015-08-16 20:39:34.787 Test[1226:34386] 上菜
秩序
把大象塞进冰箱只需要三步:打开冰箱门,把大象塞进冰箱,关上冰箱门。
- [[[[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- NSLog(@"打开冰箱门");
- [subscriber sendCompleted];
- return nil;
- }] then:^RACSignal *{
- return [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- NSLog(@"把大象塞进冰箱");
- [subscriber sendCompleted];
- return nil;
- }];
- }] then:^RACSignal *{
- return [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- NSLog(@"关上冰箱门");
- [subscriber sendCompleted];
- return nil;
- }];
- }] subscribeCompleted:^{
- NSLog(@"把大象塞进冰箱了");
- }];
- 2015-08-16 20:45:27.724 Test[1334:37870] 打开冰箱门
- 2015-08-16 20:45:27.725 Test[1334:37870] 把大象塞进冰箱
- 2015-08-16 20:45:27.725 Test[1334:37870] 关上冰箱门
- 2015-08-16 20:45:27.726 Test[1334:37870] 把大象塞进冰箱了
命令
我命令你马上投降。
- RACCommand *aCommand = [[RACCommand alloc] initWithSignalBlock:^RACSignal *(id input) {
- return [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- NSLog(@"我投降了");
- [subscriber sendCompleted];
- return nil;
- }];
- }];
- [aCommand execute:nil];
- 2015-08-16 20:54:32.492 Test[1450:41849] 我投降了
延迟
等等我,我还有10秒钟就到了。
- [[[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- NSLog(@"等等我,我还有10秒钟就到了");
- [subscriber sendNext:nil];
- [subscriber sendCompleted];
- return nil;
- }] delay:10] subscribeNext:^(id x) {
- NSLog(@"我到了");
- }];
- 2015-08-16 21:00:57.622 Test[1619:45924] 等等我,我还有10秒钟就到了
- 2015-08-16 21:01:07.624 Test[1619:45924] 我到了
重放
一次制作,多次观看。
- RACSignal *replaySignal = [[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- NSLog(@"大导演拍了一部电影《我的男票是程序员》");
- [subscriber sendNext:@"《我的男票是程序员》"];
- return nil;
- }] replay];
- [replaySignal subscribeNext:^(id x) {
- NSLog(@"小明看了%@", x);
- }];
- [replaySignal subscribeNext:^(id x) {
- NSLog(@"小红也看了%@", x);
- }];
- 2015-08-16 21:18:38.002 Test[1854:54712] 大导演拍了一部电影《我的男票是程序员》
- 2015-08-16 21:18:38.004 Test[1854:54712] 小明看了《我的男票是程序员》
- 2015-08-16 21:18:38.004 Test[1854:54712] 小红也看了《我的男票是程序员》
定时
每隔8个小时服一次药。
- [[RACSignal interval:60*60*8 onScheduler:[RACScheduler mainThreadScheduler]] subscribeNext:^(id x) {
- NSLog(@"吃药");
- }];
超时
等了你一个小时了,你还没来,我走了。
- [[[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- [[[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- NSLog(@"我快到了");
- [subscriber sendNext:nil];
- [subscriber sendCompleted];
- return nil;
- }] delay:60*70] subscribeNext:^(id x) {
- [subscriber sendNext:nil];
- [subscriber sendCompleted];
- }];
- return nil;
- }] timeout:60*60 onScheduler:[RACScheduler mainThreadScheduler]] subscribeError:^(NSError *error) {
- NSLog(@"等了你一个小时了,你还没来,我走了");
- }];
- 2015-08-16 21:40:09.068 Test[2041:64720] 我快到了
- 2015-08-16 22:40:10.048 Test[2041:64720] 等了你一个小时了,你还没来,我走了
重试
成功之前可能需要数百次失败。
- __block int failedCount = 0;
- [[[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- if (failedCount < 100) {
- failedCount++;
- NSLog(@"我失败了");
- [subscriber sendError:nil];
- }else{
- NSLog(@"经历了数百次失败后");
- [subscriber sendNext:nil];
- }
- return nil;
- }] retry] subscribeNext:^(id x) {
- NSLog(@"终于成功了");
- }];
- 2015-08-16 21:59:07.159 Test[2411:77080] 我失败了
- 2015-08-16 21:59:07.159 Test[2411:77080] 我失败了
- 2015-08-16 21:59:07.159 Test[2411:77080] 我失败了
- 2015-08-16 21:59:07.159 Test[2411:77080] 我失败了
- 2015-08-16 21:59:07.160 Test[2411:77080] 我失败了
- 2015-08-16 21:59:07.160 Test[2411:77080] 我失败了
- 2015-08-16 21:59:07.161 Test[2411:77080] 我失败了
- 2015-08-16 21:59:07.162 Test[2411:77080] 我失败了
- ...
- 2015-08-16 21:59:07.162 Test[2411:77080] 我失败了
- 2015-08-16 21:59:07.163 Test[2411:77080] 我失败了
- 2015-08-16 21:59:07.163 Test[2411:77080] 我失败了
- 2015-08-16 21:59:07.163 Test[2411:77080] 我失败了
- 2015-08-16 21:59:07.164 Test[2411:77080] 我失败了
- 2015-08-16 21:59:07.164 Test[2411:77080] 我失败了
- 2015-08-16 21:59:07.164 Test[2411:77080] 我失败了
- 2015-08-16 21:59:07.165 Test[2411:77080] 经历了数百次失败后
- 2015-08-16 21:59:07.165 Test[2411:77080] 终于成功了
节流
不好意思,这里一秒钟只能通过一个人。
- [[[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- [subscriber sendNext:@"旅客A"];
- dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
- [subscriber sendNext:@"旅客B"];
- });
- dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(2 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
- [subscriber sendNext:@"旅客C"];
- [subscriber sendNext:@"旅客D"];
- [subscriber sendNext:@"旅客E"];
- });
- dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(3 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
- [subscriber sendNext:@"旅客F"];
- });
- return nil;
- }] throttle:1] subscribeNext:^(id x) {
- NSLog(@"%@通过了",x);
- }];
- 2015-08-16 22:08:45.677 Test[2618:83764] 旅客A
- 2015-08-16 22:08:46.737 Test[2618:83764] 旅客B
- 2015-08-16 22:08:47.822 Test[2618:83764] 旅客E
- 2015-08-16 22:08:48.920 Test[2618:83764] 旅客F
条件
直到世界的尽头才能把我们分开。
- [[[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- [[RACSignal interval:1 onScheduler:[RACScheduler mainThreadScheduler]] subscribeNext:^(id x) {
- [subscriber sendNext:@"直到世界的尽头才能把我们分开"];
- }];
- return nil;
- }] takeUntil:[RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
- dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(5 * NSEC_PER_SEC)), dispatch_get_main_queue(), ^{
- NSLog(@"世界的尽头到了");
- [subscriber sendNext:@"世界的尽头到了"];
- });
- return nil;
- }]] subscribeNext:^(id x) {
- NSLog(@"%@", x);
- }];
- 2015-08-16 22:17:22.648 Test[2766:88737] 直到世界的尽头才能把我们分开
- 2015-08-16 22:17:23.648 Test[2766:88737] 直到世界的尽头才能把我们分开
- 2015-08-16 22:17:24.645 Test[2766:88737] 直到世界的尽头才能把我们分开
- 2015-08-16 22:17:25.648 Test[2766:88737] 直到世界的尽头才能把我们分开
- 2015-08-16 22:17:26.644 Test[2766:88737] 直到世界的尽头才能把我们分开
- 2015-08-16 22:17:26.645 Test[2766:88737] 世界的尽头到了
完事
ReactiveCocoa是如此优雅,一旦使用,根本停不下来,上面也只是它的一角冰山,但愿我能挑起你的兴趣