ReactiveCocoa - Learning to Think Reactively - ios

Question

I'm currently looking into the ReactiveCocoa and though I'm already a bit familiar with it's classes, I guess that I still have some problems thinking reactively.
I'd appreciate if someone more experienced could take a look at my code (which already works correctly) and point me to any things which are currently not reactive enough but implemented in a classic way just using the RAC classes.
Of course any examples from your side are highly preferable.
Briefly about the functionality of my code:
I send several asynchronous requests to an image search API, get the result as an array of links, and then use them for asynchronous downloading the images and finally draw them at a large UIImageView by replacing it's image with a new one generated every time when a new image is downloaded.
Thanks!
- (void)fillImageView:(UIImageView *)imageView withQuery:(NSString *)query {
self.timestamp = [NSDate timeIntervalSinceReferenceDate];
[[[self searchAllSignalWithQuery:query]
map:^id(NSArray *images) {
NSLog(#"Processing images. Count: %ld", images.count);
return [self processSignalWithImages:images imageView:imageView];
}]
subscribeCompleted:^{
}];
}
- (RACSignal *)searchAllSignalWithQuery:(NSString *)query {
NSMutableArray *searchSignals = [NSMutableArray array];
for (NSInteger pageIndex = 0; pageIndex &lt kSearchPageCount; pageIndex++) {
[searchSignals addObject:[self searchSignalWithQuery:query top:kSearchPageSize skip:(pageIndex * kSearchPageSize)]];
}
return [[RACSignal zip:searchSignals] flattenMap:^id(NSArray *results) {
NSMutableArray *images = [NSMutableArray array];
for (NSArray *result in results) {
[images addObjectsFromArray:result];
}
return [RACSignal return:images];
}];
}
- (RACSignal *)searchSignalWithQuery:(NSString *)query top:(NSInteger)top skip:(NSInteger)skip {
return [RACSignal createSignal:^RACDisposable *(id&ltRACSubscriber&gt subscriber) {
NSURLSessionDataTask *task = [Common searchTaskWithQuery:query top:top skip:skip completionBlock:^(NSArray *images) {
NSLog(#"Adding images. Count: %ld", images.count);
[subscriber sendNext:images];
[subscriber sendCompleted];
}];
[task resume];
return nil;
}];
}
- (RACSignal *)processSignalWithImages:(NSArray *)images imageView:(UIImageView *)imageView {
NSInteger imageIndex = 0;
NSMutableArray *downloadSignals = [NSMutableArray array];
RACScheduler *drawScheduler = [RACScheduler schedulerWithPriority:RACSchedulerPriorityDefault];
for (NSString *url in images) {
RACSignal *downloadSignal = [self downloadSignalWithURL:url];
[[downloadSignal deliverOn:[RACScheduler schedulerWithPriority:RACSchedulerPriorityBackground]] subscribeNext:^(UIImage *image) {
NSLog(#"Drawing image. Index: %ld", imageIndex);
if (!image) {
image = [UIImage imageNamed:#"error"];
}
[drawScheduler schedule:^{
UIImage *newImage = [Common imageByDrawingImage:image onImageView:imageView atIndex:imageIndex];
[[RACScheduler mainThreadScheduler] schedule:^{
imageView.image = newImage;
}];
}];
}];
[downloadSignals addObject:downloadSignal];
imageIndex++;
}
RACSignal *processSignal = [RACSignal combineLatest:downloadSignals];
[processSignal subscribeCompleted:^{
NSLog(#"Completed. Duration: %.2f seconds", ([NSDate timeIntervalSinceReferenceDate] - self.timestamp));
}];
return processSignal;
}
- (RACSignal *)downloadSignalWithURL:(NSString *)url {
return [RACSignal createSignal:^RACDisposable *(id&ltRACSubscriber&gt subscriber) {
NSURLSessionDataTask *task = [Common downloadTaskWithURL:url completionBlock:^(UIImage *image) {
[subscriber sendNext:image];
[subscriber sendCompleted];
}];
[task resume];
return nil;
}];
}