XCTest+Async.m

@implementation XCTest (Async)

+ (NSTimeInterval)waitTillReady:(BOOL (^)())isReady orTimeout:(NSTimeInterval)seconds
{
    NSTimeInterval start = [NSDate timeIntervalSinceReferenceDate];
    NSDate *loopUntil = [NSDate dateWithTimeIntervalSinceNow:seconds];

    while (!isReady() && [loopUntil timeIntervalSinceNow] > 0) {
        [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:loopUntil];
    }

    NSTimeInterval finish = [NSDate timeIntervalSinceReferenceDate];
    return (finish - start);
}

+ (void)waitForTimeout:(NSTimeInterval)seconds
{
    NSDate *loopUntil = [NSDate dateWithTimeIntervalSinceNow:seconds];
    while ([loopUntil timeIntervalSinceNow] > 0) {
        [[NSRunLoop currentRunLoop] runMode:NSDefaultRunLoopMode beforeDate:loopUntil];
    }
}

@end