Question

我有两个UITableViewControllers，它们都包含非常相似的单元格（每个单元格类有2个UIImageViews和2个UILabels）。第一个视图控制器是用Objective-C编写的，纯粹用代码实现。第二个视图控制器是用Swift编写的，并且在故事板中进行了布局。

我的问题是第一个视图控制器在滚动到顶部时抖动，而第二个视图控制器在滚动到顶部时非常平滑。这是video。

第一个TableViewController的cellForRowAtIndexPath ：

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

LYRConversation *conversation = _searching && _filteredDataSource.count ? [_filteredDataSource objectAtIndex:indexPath.row] : [_dataSource objectAtIndex:indexPath.row];

if (conversation.participants.count > 2) {
    ConversationListGroupCell *cell = (ConversationListGroupCell *)[tableView dequeueReusableCellWithIdentifier:GROUP_CELL_REUSE_ID forIndexPath:indexPath];
    [self configureGroupCell:cell atIndexPath:indexPath conversation:conversation];
    return cell;
}

ConversationListCell *cell = (ConversationListCell *)[tableView dequeueReusableCellWithIdentifier:CELL_REUSE_ID forIndexPath:indexPath];
[self configureCell:cell atIndexPath:indexPath conversation:conversation];

return cell; 
}

-(void)configureCell:(ConversationListCell *)conversationCell atIndexPath:(NSIndexPath *)indexPath conversation:(LYRConversation *)conversation
{
    [conversationCell updateAvatarWithUrl:[NSURL URLWithString:[self avatarStringUrlForConversation:conversation]]];
    [conversationCell updateTitle:[self titleForConversation:conversation]];
    [conversationCell updateUnreadMessageIndicator:conversation];
    NSArray *otherParticipants = [[PersistentCache sharedCache] cachedUsersForUserIDs:conversation.participants];
    conversationCell.preview.text = [((PFUser *)otherParticipants.lastObject) objectForKey:@"jobTitle"];
    [UIView updateStatusIndicatorOfConversation:otherParticipants statusIndicator:conversationCell.status];
}

-(void)configureGroupCell:(ConversationListGroupCell *)conversationGroupCell atIndexPath:(NSIndexPath *)indexPath conversation:(LYRConversation *)conversation {
NSArray *urls = [self avatarStringUrlsForConversation:conversation];
if (urls.count == conversation.participants.count - 1) {
    NSURL *url1 = [NSURL URLWithString:urls[0]];
    if(url1 != NULL) {
        downloadImageThenSetForImageView(conversationGroupCell.avatar1, url1);
    }
    NSURL *url2 = [NSURL URLWithString:urls[1]];
    if (url2 != NULL) {
        downloadImageThenSetForImageView(conversationGroupCell.avatar2, url2);
    }
    if (urls.count > 2) {
        NSURL *url3 = [NSURL URLWithString:urls[2]];
        if (url3 != NULL) {
            downloadImageThenSetForImageView(conversationGroupCell.avatar3, url3);
        }
        conversationGroupCell.avatar3.hidden = NO;
    }
    if (urls.count > 3){
        conversationGroupCell.plusOne.hidden = NO;
        conversationGroupCell.plusOne.text = [NSString stringWithFormat:@"+%lu", urls.count - 3];
    }
}

conversationGroupCell.title.text = [self titleForConversation:conversation];

if (conversation.lastMessage.isUnread) {
    //[self.unreadMessageIndicator setImage:[ConversationListCell unreadBlue] forState:UIControlStateNormal];
    [conversationGroupCell.unreadMessageIcon setImage:[Assets unreadBlue]];
}
else {
    //[self.unreadMessageIndicator setImage:[ConversationListCell unreadGray] forState:UIControlStateNormal];
    [conversationGroupCell.unreadMessageIcon setImage:[Assets unreadGray]];
}

NSString *idOfLastSender = conversation.lastMessage.sender.userID;
NSString *lastMessageText = NULL;
if ([idOfLastSender isEqualToString:self.layerClient.authenticatedUserID]) {
    lastMessageText = @"You";
}
else {
    lastMessageText = [[PersistentCache sharedCache] resolvedFullNamesFromParticipants:@[idOfLastSender]].firstObject;
}
conversationGroupCell.preview.text = [NSString stringWithFormat:@"%@ 

sent last message", lastMessageText];
}

第二个TableViewController的

cellForRowAtIndexPath：

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> CallLogCell
{
    guard let cell = tableView.dequeueReusableCellWithIdentifier(CellIdentifiers.PhoneCell.rawValue, forIndexPath: indexPath) as? CallLogCell else {
        return CallLogCell()
    }
    configureCell(cell, indexPath: indexPath)
    return cell
}

func configureCell(cell: CallLogCell, indexPath: NSIndexPath) {

    let callParticipantInfo = CallLog.callLogDataSource[indexPath.row]
    // TODO: Add all these to the cell class as methods
    // TODO: Make sure UI looks okay if any of this stuff is nil

    // Set Name
    guard let callParticipant = callParticipantInfo[CallLogDataSourceIndices.Object] as? PFUser else {
        return
    }
    cell.nameLabel.text     = callParticipant.fullName()

    // Set Image
    let imageUrlString = callParticipant[ParseKeys.ImageUrl.rawValue] as? String ?? ""
    if let imageUrl       = NSURL(string: imageUrlString) {
        downloadImageThenSetForImageView(cell.picture, imageUrl)
    }
    else {
        cell.picture.image = Assets.placeholder()
    }

    // Set Status
    let status = callParticipant[ParseKeys.Status.rawValue] as? NSNumber ?? NSNumber.statusCodeUnknown()
    cell.statusIndicator.backgroundColor = UIColor.PNGStatusColorForStatusCode(status.integerValue)

    // Set Missed call
    let missedCall = callParticipantInfo[CallLogDataSourceIndices.Missed] as? String ?? ""
    if missedCall != "" && Int(missedCall) != nil {
        cell.updateMissedCallIndicator(Int(missedCall)!)
    }

    // Set Job Title
    let jobTitle = callParticipant[ParseKeys.JobTitle.rawValue]
    cell.jobTitle.text = jobTitle as? String

    // Set Date
    if let callDate = callParticipantInfo[CallLogDataSourceIndices.Date] as? String {
        cell.date.text = formatDate(callDate)
        } 
}

两个视图控制器使用的方法

void downloadImageThenSetForImageView(UIImageView * imageView, NSURL *url) {
[[SDWebImageManager sharedManager] downloadImageWithURL:url options:0
                                               progress:^(NSInteger receivedSize, NSInteger expectedSize) {

                                               }
                                              completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, BOOL finished, NSURL *imageURL) {
                                                  imageView.image = [UIImage resize:image newSize:imageView.bounds.size];
                                                  }];

}

extension UIImage {
class func resize(bigImage: UIImage, newSize: CGSize) -> UIImage {
    let hasAlpha = false
    let scale: CGFloat = 0.0 // Automatically use scale factor of main screen

    UIGraphicsBeginImageContextWithOptions(newSize, !hasAlpha, scale)
    bigImage.drawInRect(CGRect(origin: CGPointZero, size: newSize))

    let scaledImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()
    return scaledImage
}

SDWebImage：https://github.com/rs/SDWebImage - 根据文档，图片下载器是异步的。

乐器的屏幕截图＆＃39;时间分析器分析

我在滞后视图控制器上滚动几次后拍摄了这个截图。如果我隐藏系统库，那么它没有显示任何让我相信我的代码没有瓶颈的东西？

两个非常相似的表视图具有不同的滚动质量

0 个答案: