gistfile1.m

- (void)trimDiskToDate:(NSDate *)trimDate
{
    NSArray *keysSortedByDate = [_dates keysSortedByValueUsingSelector:@selector(compare:)];
    
    for (NSString *key in keysSortedByDate) { // oldest files first
        NSDate *accessDate = [_dates objectForKey:key];
        if (!accessDate)
            continue;
        
        if ([accessDate compare:trimDate] == NSOrderedAscending) { // older than trim date
            [self removeFileAndExecuteBlocksForKey:key];
        } else {
            break;
        }
    }
}

- (void)trimToAgeLimitRecursively
{
    if (_ageLimit == 0.0)
        return;
    
    NSDate *date = [[NSDate alloc] initWithTimeIntervalSinceNow:-_ageLimit];
    [self trimDiskToDate:date];
    
    __weak TMDiskCache *weakSelf = self;
    
    dispatch_time_t time = dispatch_time(DISPATCH_TIME_NOW, (int64_t)(_ageLimit * NSEC_PER_SEC));
    dispatch_after(time, _queue, ^(void) {
        TMDiskCache *strongSelf = weakSelf;
        [strongSelf trimToAgeLimitRecursively];
    });
}