ReactiveCocoa. Optional retry on error

#1. Simple retry

// Taken from http://www.slideshare.net/manuelmaly/reactivecocoa-goodness-part-i-of-ii
// Exact presentation slide: http://image.slidesharecdn.com/presentation-141009165841-conversion-gate01/95/reactivecocoa-goodness-part-i-of-ii-37-638.jpg?cb=1412892113

// Try to repeat signal 3 times
static NSUInteger const retryAttempts  = 2;
static NSTimeInterval const retrydelay = 1.;

RACSignal *signal = ...;
RACSignal *result = [[signal catch:^RACSignal *(NSError *error) {
	return [[[RACSignal empty] delay:retrydelay]
			concat:[RACSignal error:error]];
}] retry:retryAttempts];

#2. Optional retry

// Improved implementation
// Supports optional breaking of retry-cycle

// Try to repeat signal 3 times
static NSUInteger const retryAttempts  = 2;
static NSTimeInterval const retrydelay = 1.;

static NSUInteger attempt;

- (void)performSignal {
	attempt = 0;

	RACSignal *signal = ...;
	RACSignal *result = [self retry:signal];
}

- (RACSignal *)retry:(RACSignal *)signal {
	return [signal catch:^RACSignal *(NSError *error) {
		attempt++;

		if (attempt <= retryAttempts && [self allowRetryOnError:error]) {
			return [[[RACSignal empty] delay:retrydelay] then:^RACSignal *{
				return [self retry:signal];
			}];
		}

		return [RACSignal error:error];
	}];
}

- (BOOL)allowRetryOnError:(NSError *)error {
	return ...;
}

Thanks for your sharing,
How can I make a retry operation until viewController dismiss?