ReactiveCocoa 用法实例
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。
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@weakify(self);
[RACObserve(self, value) subscribeNext:^(NSString* x) {
@strongify(self);
NSLog(@"你动了");
}];
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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。
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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 @"";
}];
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双边
你向西,他就向东,他向左,你就向右。
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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";
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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
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代理
你是程序员,你帮我写个app吧。
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@protocol Programmer <NSObject>
- (void)makeAnApp;
@end
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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];
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2015-08-15 20:46:45.720 Test[2817:114564] 花了一个月,app写好了
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广播
知道你的频道,我就能听到你了。
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[[[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"}];
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2015-08-15 20:41:15.786 Test[2734:111505] 技巧:用心写
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连接
生活是一个故事接一个故事。
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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);
}];
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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
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合并
污水都应该流入污水处理厂被处理。
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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);
}];
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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
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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。
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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);
}];
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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
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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。
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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);
}];
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2015-08-15 20:34:24.274 Test[2660:108483] 我们是红白的
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映射
我可以点石成金。
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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);
}];
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2015-08-16 20:00:12.853 Test[740:15871] 金
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归约
糖加水变成糖水。
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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);
}];
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2015-08-16 20:07:00.356 Test[807:19177] 糖水
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过滤
未满十八岁,禁止进入。
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[[[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);
}];
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2015-08-16 20:11:20.071 Test[860:21214] 21
2015-08-16 20:11:20.071 Test[860:21214] 30
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扁平
打蛋液,煎鸡蛋,上盘。
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[[[[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);
}];
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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
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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。
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[[[[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");
}];
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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
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命令
我命令你马上投降。
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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];
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2015-08-16 20:54:32.492 Test[1450:41849] 我投降了
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延迟
等等我,我还有10秒钟就到了。
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[[[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");
}];
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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
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重放
一次制作,多次观看。
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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);
}];
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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》
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定时
每隔8个小时服一次药。
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[[RACSignal interval:60*60*8 onScheduler:[RACScheduler mainThreadScheduler]] subscribeNext:^(id x) {
NSLog(@"吃药");
}];
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超时
等了你一个小时了,你还没来,我走了。
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[[[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");
}];
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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
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重试
成功之前可能需要数百次失败。
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__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");
}];
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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
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节流
不好意思,这里一秒钟只能通过一个人。
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[[[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);
}];
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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
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条件
直到世界的尽头才能把我们
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[[[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);
}];
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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
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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。
转载自:http://ios.jobbole.com/82356/