Change a timestamp logic in JSQMessagesViewController

Question

Its possible change logic of collectionView: attributedTextForCellTopLabelAtIndexPath: delegate method for show date timestamp not by indexPath.item % 4 == 0? how like in SOMessaging day by day? or whatever?

this coding is for displaying timestamp.

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

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

    return 0.0f;
}

Current existing logic is displaying same timestamp is duplicated as follow.

Answer 1

Because each JSQMessage object has a date property, you can simply compare the date of each message to the date of the previous message.

[thisMessageDate timeIntervalSinceDate:(NSDate *)previousMessageDate] will give you the difference in seconds. If the difference is greater than, say, a minute (or whatever time interval you desire), then display a timestamp.

This is how I'm doing it:

- (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;
}

And then just repeat this logic to make sure the timestamps have the correct heights:

- (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;
}

Answer 2

To show timestamp cell only day by day;

With @cerenali's answer, we may have problems for dates which have different days but close times. Like:

msgDate1 = 31/03/2016 23:55
msgDate2 = 01/04/2016 00:07

to handle this, i replaced the logic inside if with:

BOOL checkTime = message.date.year != previousMessage.date.year || message.date.month != previousMessage.date.month || message.date.day != previousMessage.date.day;

and the final code will be:

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

    if (indexPath.item - 1 > -1) {
        JSQMessage *previousMessage = [self.messages objectAtIndex:indexPath.item - 1];
        BOOL checkTime = message.date.year != previousMessage.date.year || message.date.month != previousMessage.date.month || message.date.day != previousMessage.date.day;
        if (checkTime) {
            return [[JSQMessagesTimestampFormatter sharedFormatter] attributedTimestampForDate:message.date];
        }
    }

Note: I am using DateTools in my project.

Answer 3

Thanks, @cerenali for the nice answer.

In Swift-3, @cerenali code can be written in:-

     override func collectionView(_ collectionView: JSQMessagesCollectionView, attributedTextForCellTopLabelAt indexPath: IndexPath) -> NSAttributedString? {

                    let message = self.messages[indexPath.item]
                    if indexPath.item == 0 {
                        return JSQMessagesTimestampFormatter.shared().attributedTimestamp(for: message.date)
                    }

                    if indexPath.item -  1 > 0{
                        let previousMessage = self.messages[indexPath.item - 1 ]

                        if  ( ( message.date.timeIntervalSince(previousMessage.date) / 60 ) > 1){
                            return JSQMessagesTimestampFormatter.shared().attributedTimestamp(for: message.date)
                        }
                    }

                    return nil  
    }

     override func collectionView(_ collectionView: JSQMessagesCollectionView, layout collectionViewLayout: JSQMessagesCollectionViewFlowLayout, heightForCellTopLabelAt indexPath: IndexPath) -> CGFloat {

            if indexPath.item == 0 {
                return kJSQMessagesCollectionViewCellLabelHeightDefault
            }

            if indexPath.item -  1 > 0{
                let message = self.messages[indexPath.item]
                let previousMessage = self.messages[indexPath.item - 1 ]

                if  ( ( message.date.timeIntervalSince(previousMessage.date) / 60 ) > 1){
                    return kJSQMessagesCollectionViewCellLabelHeightDefault
                }
            }
            return 0.0
        }