ios - 更改 JSQMessagesViewController 中的时间戳逻辑

Question

collectionView可能的变化逻辑:attributedTextForCellTopLabelAtIndexPath: delegate method for show date timestamp not by indexPath.item % 4 == 0?每天在 SOMessaging 中感觉如何？还是什么？

此编码用于显示时间戳。

- (CGFloat)collectionView:(JSQMessagesCollectionView *)collectionView
                   layout:(JSQMessagesCollectionViewFlowLayout *)collectionViewLayout heightForCellTopLabelAtIndexPath:(NSIndexPath *)indexPath
{

    if (indexPath.item % 3 == 0) {
        return kJSQMessagesCollectionViewCellLabelHeightDefault;
    }

    return 0.0f;
}

当前存在的逻辑显示相同的时间戳被复制如下。

Answer 1

因为每个 JSQMessage 对象都有一个 date 属性，您可以简单地将每条消息的日期与前一条消息的日期进行比较。

[thisMessageDate timeIntervalSinceDate:(NSDate *)previousMessageDate] 将为您提供秒数差异。如果差异大于一分钟(或您想要的任何时间间隔)，则显示时间戳。

我是这样做的:

- (NSAttributedString *)collectionView:(JSQMessagesCollectionView *)collectionView attributedTextForCellTopLabelAtIndexPath:(NSIndexPath *)indexPath {
JSQMessage *message = [self.messages objectAtIndex:indexPath.item];

  if (indexPath.item == 0) {
      return [[JSQMessagesTimestampFormatter sharedFormatter] attributedTimestampForDate:message.date];
  }

  if (indexPath.item - 1 > 0) {
    JSQMessage *previousMessage = [self.messages objectAtIndex:indexPath.item - 1];

    if ([message.date timeIntervalSinceDate:previousMessage.date] / 60 > 1) {
        return [[JSQMessagesTimestampFormatter sharedFormatter] attributedTimestampForDate:message.date];
    }
  }

  return nil;
}

然后只需重复此逻辑以确保时间戳具有正确的高度:

- (CGFloat)collectionView:(JSQMessagesCollectionView *)collectionView
               layout:(JSQMessagesCollectionViewFlowLayout *)collectionViewLayout heightForCellTopLabelAtIndexPath:(NSIndexPath *)indexPath {

  if (indexPath.item == 0) {
    return kJSQMessagesCollectionViewCellLabelHeightDefault;
  }

  if (indexPath.item - 1 > 0) {
    JSQMessage *previousMessage = [self.messages objectAtIndex:indexPath.item - 1];
    JSQMessage *message = [self.messages objectAtIndex:indexPath.item];

    if ([message.date timeIntervalSinceDate:previousMessage.date] / 60 > 1) {
        return kJSQMessagesCollectionViewCellLabelHeightDefault;
    }
  }

  return 0.0f;
}