I put // before the first operator to achieve this. clang-format detects it as a comment and automatically starts on the next line for the rest of the statement. You don't need to put it on each line, usually the first is enough but sometimes not (it also depends on other settings in your .clang-format file).

So it looks a bit like:

[[self.myService indexCase] // subscribeNext:^(id response) { DDLogDebug(@"response : %@", response); } error:^(NSError *error) { [self.dataManager sendError:error]; }];

I use this trick to make clang-format break the code where I want. It's a bit hacky, might even seem ugly to some, but I consider the benefits of increased readability more valuable than occasional empty comment statements so it doesn't hurt my eyes much.