情景一：如下图，当下面其中一项发生变化的时候，确认修改的按钮变成可点击状态
RACSignal *validseviceTypeField = [RACObserve(self, service_type) //RACObserve(self, service_type) 观察控制器self 的属性service_type的值变化
map:^id(NSString *value) { //flattenMap,Map用于把源信号内容映射成新的内容
if ([value isEqualToString:self.item.service_cate_id]) {
return @(0);
}
return @(1);
}];
RACSignal *validNameField = [[self.detailView.nameLab rac_textSignal] map:^id(NSString *value) {
if ([value isEqualToString:self.item.service_name]) { //value就是textField改变后的值，self.item.service_cate_id是初始值
return @(0);
}
return @(1);
}];
RACSignal *validPriceField = [[self.detailView.priceLab rac_textSignal] map:^id(NSString *value) {
if ([value isEqualToString:self.item.service_price]) {
return @(0);
}
return @(1);
}];
RACSignal *havaPicSignal = [RACObserve(vc, photoIsChange) //vc是图片中服务详情图的控制器，photoIsChange是vc的一个bool属性，记录图片是否改动过
map:^id(NSNumber *photoIsChange) {
return @([photoIsChange integerValue]);
}];
//RAC(btn, enabled) 调用set方法
//combineLatest合并各信号源Signal 得到（reduce）的结果
RAC(btn, enabled) = [RACSignal combineLatest:@[validseviceTypeField, validNameField, validPriceField, havaPicSignal] reduce:^id(NSNumber *validseviceTypeField, NSNumber *validNameField, NSNumber *validPriceField, NSNumber *validPic){
return @([validseviceTypeField boolValue] || [validNameField boolValue] || [validPriceField boolValue] || [validPic boolValue]);
}];
情景二：网络请求
如下是利用rac实现的网络请求“次基类”BaseViewModel（还有基类就是NetworkTools网络请求类）的post请求
+ (RACSignal *)postRequestWithUrl:(NSString *)url parameter:(NSDictionary *)params
{
url = [NetworkTools concatUrl:url];
params = [[NetworkTools sharedTools] addExtraParameters:params];
if ([url respondsToSelector:@selector(length)] && url.length == 0) {
return [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber) {
[subscriber sendError:[CXXError errWithState:NO info:@"URL为空"]];
[subscriber sendCompleted];
return nil;
}];
}
/**
RACSignal的Subscription过程概括起来可以分为三个步骤：
1.[RACSignal createSignal]来获得signal
2.[signal subscribeNext:]来获得subscriber，然后进行subscription
3.进入didSubscribe，通过[subscriber sendNext:]来执行next block
*/
//1.[RACSignal createSignal]来获得signal
return [RACSignal createSignal:^RACDisposable *(id<RACSubscriber> subscriber{ //2.获得了subscriber，然后进行subscription
[[NetworkTools sharedTools] POST:url parameters:params progress:nil success:^(NSURLSessionDataTask * _Nonnull task, id _Nullable responseObject) {
id success = [responseObject valueForKey:@"success"];
if (![success isKindOfClass:NSNull.class] && [success boolValue]) {
//3.进入didSubscribe，通过[subscriber sendNext:]来执行next block
[subscriber sendNext:responseObject];
} else {
[subscriber sendError:[CXXError errWithState:NO info:responseObject[@"info"]]];
}
[subscriber sendCompleted];
// 信号在释放的时候要完成的Block
[RACDisposable disposableWithBlock:^{
[task cancel];
}];
} failure:^(NSURLSessionDataTask * _Nullable task, NSError * _Nonnull error) {
[subscriber sendError:[CXXError errWithError:error]];
[subscriber sendCompleted];
[RACDisposable disposableWithBlock:^{
[task cancel];
}];
}];
return nil;
}];
}
当继承BaseViewModel的网络请求就如下请求：
+ (RACSignal *)unbindBankCardWithId:(NSString *)cardId{
return [self postRequestWithUrl:@"Bankcard/unbundling_card" parameter:@{@"card_id":cardId?:@""}];
}
调用网络请求
[[[CXXBankViewModel unbindBankCardWithId:weakSelf.card_id] doNext:^(id x) {
//doNext: 执行Next之前,会先执行这个Block,doCompleted: 执行sendCompleted之前,会先执行这个Block
//执行完doNext:中的方法后,返回一个新的signal给原来的信号,并去执行subscribeNext中的相应方法
[weakSelf showHudInView:nil hint:@"解除银行卡中..."];
}] subscribeNext:^(NSDictionary *x) { //subscribeNext触发上面网络请求sendNext:方法，拿到responseObject，可参考下图signal的运行顺序
[weakSelf hideHud];
[weakSelf showHint:@"已解除绑定"];
} error:^(NSError *error) {
[weakSelf hideHud];
[weakSelf showHint:((CXXError *) error).info];
}];
附带网上资料查找的一张signal的运行顺序截图：
