如何从SQLite3行中获取日期或日期时间?

sqlite3_column_date 我需要:

int i = 0;
for (NSString *key in [self valuesWithTypes]) {
  id value;
  if ([[[self valuesWithTypes] objectForKey:key] isKindOfClass:[NSString class]]) {
    value = [[NSString stringWithUTF8String:(char *)sqlite3_column_text(statement, i)] autorelease];
  }
  else if ([[[self valuesWithTypes] objectForKey:key] isKindOfClass:[NSNumber class]]) {
    value = [[NSNumber numberWithDouble:sqlite3_column_double(statement, i)] autorelease];
  }
  else if ([[[self valuesWithTypes] objectForKey:key] isKindOfClass:[NSDate class]]) {
//  value = // WTF
  }
  else if ([[[self valuesWithTypes] objectForKey:key] isKindOfClass:[NSData class]]) {
    value = [[NSData dataWithBytes:sqlite3_column_blob(statement, i) length:sqlite3_column_bytes(statement, i)] autorelease];
  }
  [rowDictionary setValue:value forKey:key];
  i++;
}

谢谢