ReactiveCocoa信號(hào)(RACStream (Operations)文件中)操作像Swift里面的一些高階函數(shù)一樣有map,flattenMap,reduce, filter等操作利职。
1. map
(Returns a new stream with the mapped values.)
<pre>
[signale map:^id(id value) {
1??
return [NSString stringWithFormat:@"輸出:%@",value];2??
}] subscribeNext:^(id x) {
NSLog(@"090909----->%@",x);3??
}];
</pre>
其中:
1??：傳入一個(gè)block類型,返回id類型的對(duì)象,參數(shù)是value
2??：value就是源信號(hào)的內(nèi)容帜讲，直接拿到源信號(hào)的內(nèi)容做處理。并返回相關(guān)id
3??：x表示經(jīng)過處理后的value值
2. flattenMap
(Returns a new stream which represents the combined streams resulting from mapping block.)
<pre>
[signal flattenMap:^RACStream *(id value) {
1??
return [RACSignal return:[NSString stringWithFormat:@"輸出09090：%@",value]]; 2??
}] subscribeNext:^(id x) {
NSLog(@"%@",x); 3??
}];
]
</pre>
其中：
1??：傳入一個(gè)block谷婆，block類型是返回值RACStream瞬女，參數(shù)value
2??：參數(shù)value就是源信號(hào)的內(nèi)容肺缕，拿到源信號(hào)的內(nèi)容做處理狈涮。注意這里返回的是一個(gè)RACStream信號(hào)類,不是id對(duì)象。
3??:輸出經(jīng)過處理的value內(nèi)容涯鲁。
3. reduce
(Returns a signal which sends the results from each invocation of reduceBlock.)
<pre>
RACSignal *signalA = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
[subscriber sendNext:@"A"];
[subscriber sendCompleted];
return nil;
}];
RACSignal *signalB = [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
[subscriber sendNext:@"B"];
[subscriber sendCompleted];
return nil;
}];
RACSignal *reduceSignal = [RACSignal combineLatest:@[signalA,signalB] reduce:^id(NSString *x,NSString *y){
return [NSString stringWithFormat:@"%@ %@",x,y];
}];
[reduceSignal subscribeNext:^(id x) {
NSLog(@"%@",x); ---->A B
}];
</pre>
其中:
常見的用法巷查，（先組合在聚合）。combineLatest:(id<NSFastEnumeration>)signals reduce:(id (^)())reduceBlock
reduce中的block簡介:
reduceblcok中的參數(shù)抹腿，有多少信號(hào)組合吮便，reduceblcok就有多少參數(shù)，每個(gè)參數(shù)就是之前信號(hào)發(fā)出的內(nèi)容
reduceblcok的返回值：聚合信號(hào)之后的內(nèi)容幢踏。
4. filter
Filters out values in the receiver that don't pass the given test. This corresponds to the Where method in Rx.
Returns a new stream with only those values that passed.
過濾不符合要求的信號(hào)，返回符合要求的信號(hào)许师。
<pre>
[[textFiled.rac_textSignal filter:^BOOL(NSString *value) {
return value.length>3;
}] subscribeNext:^(id x) {
NSLog(@"%@",x);
}];
當(dāng)輸入框的內(nèi)容長度>3時(shí)房蝉，才有輸出。
</pre>
