Question

我正常做＆＃34;将自己的标签/图片添加到cell.contentview＆＃34;来自控制器的cellForRowAtIndexPath。我试图让其中一个标签具有动画滚动文本：也就是说，如果标签中的文本溢出了viewCell宽度，则单元格中的标签应该滚动文本（动画 - 而非手动）。此外，整个tableview +滚动文本应该适用于iPhone和iPad（所以一切都需要相应地自动调整）。

切入追逐，问题是：

如何获取cell.contentView的子视图以及时更新它的帧大小，以便测试此子视图中的文本是否溢出。

或许，这是否是正确的方法呢？

这是我的意思的图像（secondLabel等在下面解释）：

现在您可以继续阅读详细信息：

我尝试的方法是让cellForRowAtIndexPath将自定义UISCrollLabelView实例添加到单元格的contentView中。这个自定义类实际上是一个内部管理UILabel的UIView。

UISCrollLabelView应该自动调整它不会溢出表格单元格（应该适用于iPhone和iPad）。然后，根据cellForRowAtIndexPath传递给它的文本的长度，它应该自动调整其内部标签以适合所有文本，如果标签最终溢出视图（self），则动画滚动UILabel。

我有一些问题，但主要的一个是：UIScrollableView基于比较其内部标签的frame.size.width与self.frame.size.width来触发（或不触发）动画。但显然，自我框架宽度需要一些时间才能从插入cell.contenView后从0更新到最终调整大小的大小。这意味着当我的自定义UIScrollLabelView测试(label.frame.size.width > self.frame.size.width)时，这始终为true，并且不会溢出的文本仍会滚动。大约一秒钟后，self.frame会更新到正确的大小。

这里的cellForRowAtIndexPath（secondLabel是这里的scrollView）：

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
  UIImageSmartView *cachedImage;
  UILabel *mainLabel;
  UIScrollLabelView *secondLabel;

  static NSString *CellIdentifier = @"Cell";

  UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
  if (cell == nil) 
  {
    cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
                                   reuseIdentifier:CellIdentifier] autorelease];

    cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
    cell.selectionStyle = UITableViewCellSelectionStyleGray;

    mainLabel = [[[UILabel alloc] initWithFrame:CGRectMake(70, 0, 0, 20)] autorelease];
    mainLabel.font = [UIFont boldSystemFontOfSize:18];
    mainLabel.textAlignment = UITextAlignmentLeft;
    mainLabel.textColor = [UIColor blackColor];
    mainLabel.backgroundColor = [UIColor clearColor];
    mainLabel.autoresizingMask = (UIViewAutoresizingFlexibleHeight | UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleRightMargin);
    mainLabel.tag = MAINLABEL_TAG;

    secondLabel = [[[UIScrollLabelView alloc] initWithFrame:CGRectMake(70, 40, 0, 20)] autorelease];
    secondLabel.autoresizingMask = (UIViewAutoresizingFlexibleWidth | UIViewAutoresizingFlexibleRightMargin);
    //secondLabel.backgroundColor = [UIColor clearColor];
    secondLabel.tag = SECONDLABEL_TAG;

    cachedImage = [[UIImageSmartView alloc] initWithFrame:CGRectMake(5, 5, 57, 80)];
    cachedImage.tag = PHOTO_TAG;

    [cell.contentView addSubview:cachedImage];
    [cell.contentView addSubview:mainLabel];
    [cell.contentView addSubview:secondLabel];

  }
  else
  {
    cachedImage = (UIImageSmartView*)[cell.contentView viewWithTag:PHOTO_TAG];
    mainLabel = (UILabel*)[cell.contentView viewWithTag:MAINLABEL_TAG];
    secondLabel = (UIScrollLabelView*)[cell.contentView viewWithTag:SECONDLABEL_TAG]; 
  }

  // Configure the cell...

  NSString *ImageName = [[dbData objectAtIndex:indexPath.row] objectAtIndex:2];
  NSString *imageURL = [NSString stringWithFormat:@"http://someserver", referencingTable];
  [cachedImage loadAndCacheImageFromFile:ImageName fromURL:imageURL inSize:CGSizeMake(57, 80) withBorderWidth:4];

  mainLabel.text = [[dbData objectAtIndex:indexPath.row] objectAtIndex:0];

  // -> At this point I load the text into the "scrolling label" 
  //    (actually a UIView with a label)
  [secondLabel setScrollingText:[[dbData objectAtIndex:indexPath.row] objectAtIndex:1]];

  return cell;
}

到目前为止我的UIScrollLabelView实现看起来像这样：

@implementation UIScrollLabelView

- (id)initWithFrame:(CGRect)frame
{
    self = [super initWithFrame:frame];
    if (self) 
    {
        // Initialization code
      isScrolling = NO;

      self.clipsToBounds = YES;
      UILabel *label = [[[UILabel alloc] init] autorelease];
      label.font = [UIFont systemFontOfSize:14.0];
      label.textAlignment = UITextAlignmentLeft;
      label.textColor = [UIColor darkGrayColor];
      label.backgroundColor = [UIColor greenColor];
      self.backgroundColor = [UIColor redColor];
      //label.backgroundColor = [UIColor clearColor];

      [self addSubview: label];

    }
    return self;
}

- (void)setScrollingText:(NSString*)text
{
  [self setNeedsLayout];
  UILabel *label = [[self subviews ] objectAtIndex:0];
  label.text = text;
  [label sizeToFit];

  if(label.frame.size.width > self.frame.size.width)
    [self scrollText];

}

- (void)scrollText
{
  if(isScrolling)
        return;

  isScrolling = YES;

  UILabel *label = [[self subviews ] objectAtIndex:0];

    [UIView beginAnimations:@"scroll" context:nil];
    [UIView setAnimationBeginsFromCurrentState:YES];
    [UIView setAnimationDelegate:self];
    [UIView setAnimationCurve:UIViewAnimationCurveLinear];
    [UIView setAnimationDidStopSelector:@selector(scrollDidComplete)];
    [UIView setAnimationDuration: label.frame.size.width/(float)100];

    CGRect frame = label.frame;
    if(frame.origin.x == 0)
      frame.origin.x = frame.origin.x - (frame.size.width - self.frame.size.width); 
    else
      frame.origin.x = 0;

    label.frame = frame;    
    [UIView commitAnimations];

}

- (void)scrollDidComplete
{
  isScrolling = NO;
  [NSTimer scheduledTimerWithTimeInterval:1 target:self selector:@selector(scrollText) userInfo:nil repeats:NO];
} 


@end

Answer 1

当您尚未定义单元格的大小时，您正在设置标签大小。然后你再也不会检查实际尺寸了。您需要覆盖setFrame和setBounds以捕获帧大小更改。

UIView框架没有按时更新大小以在UILabel中创建滚动文本动画

1 个答案: