具有动态内容、动态布局和动态高度的 UITableViewCell
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【中文标题】具有动态内容、动态布局和动态高度的 UITableViewCell【英文标题】：UITableViewCell with dynamic content, dynamic layout and thus a dynamic height 【发布时间】：2010-10-20 08:59:49 【问题描述】：我有一个 UITableView，它有时会在加载时停止响应。我不知道为什么会发生这种情况，我想知道这是否可能是我在 cellForRowAtIndexPath 中所做的单元格布局，因为我的内容是动态的，因此每次都必须采用子视图的布局。
有没有更好的方法来实现我想要的？或者这还有什么问题吗？
这是我写的代码：
首先创建自定义单元格并将不同视图添加到内容视图的方法：
- (UITableViewCell *)tableViewCellWithReuseIdentifier:(NSString *)identifier
UITableViewCell *cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:identifier] autorelease];
UILabel *titleLbl, *amountLbl, *title2Lbl, *numberLbl, *mergeLbl, *typeLbl;
UIColor *bgColor, *blackColor, *amountColor , *title2Color;
UIColor *clearColor = [UIColor clearColor];
bgColor = [UIColor clearColor];
title2Color = [UIColor colorWithRed:0.1 green:0.1 blue:0.6 alpha:1];
amountColor = [UIColor redColor];
blackColor = [UIColor blackColor];
//The number
numberLbl = [[UILabel alloc] initWithFrame:CGRectZero];
numberLbl.tag = kNumberLblTag;
numberLbl.font = [UIFont systemFontOfSize:12];
numberLbl.textAlignment = UITextAlignmentLeft;
numberLbl.textColor = blackColor;
numberLbl.backgroundColor = clearColor;
numberLbl.numberOfLines = 0;
[cell.contentView addSubview:numberLbl];
[numberLbl release];
amountLbl = [[UILabel alloc] initWithFrame:CGRectZero];
amountLbl.tag = kamountLblTag;
amountLbl.font = [UIFont systemFontOfSize:12];
amountLbl.textAlignment = UITextAlignmentLeft;
amountLbl.textColor = amountColor;
amountLbl.backgroundColor = clearColor;
amountLbl.numberOfLines = 0;
[cell.contentView addSubview:amountLbl];
[amountLbl release];
mergeLbl = [[UILabel alloc] initWithFrame:CGRectZero] ;
mergeLbl.tag = kMergeLblTag;
mergeLbl.font = [UIFont systemFontOfSize:12];
mergeLbl.textAlignment = UITextAlignmentLeft;
mergeLbl.textColor = blackColor;
mergeLbl.backgroundColor = clearColor;
mergeLbl.numberOfLines = 0;
[cell.contentView addSubview:mergeLbl];
[mergeLbl release];
typeLbl = [[UILabel alloc] initWithFrame:CGRectZero];
typeLbl.tag = kTypeLblTag;
typeLbl.font = [UIFont systemFontOfSize:12];
typeLbl.textAlignment = UITextAlignmentLeft;
typeLbl.textColor = blackColor;
typeLbl.backgroundColor = clearColor;
typeLbl.numberOfLines = 1;
[cell.contentView addSubview:typeLbl];
[typeLbl release];
titleLbl = [[UILabel alloc] initWithFrame:CGRectZero];
titleLbl.tag = kTitleLblTag;
titleLbl.font = [UIFont systemFontOfSize:14];
titleLbl.textAlignment = UITextAlignmentLeft;
titleLbl.textColor = blackColor;
titleLbl.backgroundColor = clearColor;
titleLbl.numberOfLines = 0;
[cell.contentView addSubview:titleLbl];
[titleLbl release];
title2Lbl = [[UILabel alloc] initWithFrame:CGRectZero];
title2Lbl.tag = ktitle2LblTag;
title2Lbl.font = [UIFont systemFontOfSize:12];
title2Lbl.textAlignment = UITextAlignmentLeft;
title2Lbl.textColor = title2Color;
title2Lbl.backgroundColor = clearColor;
title2Lbl.numberOfLines = 0;
[cell.contentView addSubview:title2Lbl];
[title2Lbl release];
UIView *bgView = [[UIView alloc]initWithFrame:CGRectZero];
bgView.backgroundColor = bgColor;
cell.backgroundView = bgView;
[bgView release];
NSLog(@"tableViewCellWithReuseIdentifier");
return cell;
这里是调整每个单元格子视图大小的方法：
// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
static NSString *CellIdentifier = @"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier: CellIdentifier];
NSUInteger row = [indexPath row];
NSUInteger section = [indexPath section];
NSUInteger r = row+(section*100);
if (cell == nil)
cell = [self tableViewCellWithReuseIdentifier: CellIdentifier];
UIColor *bgColor, *clearColor = [UIColor clearColor];
//set the rePointer to the actual array
if (r < [results count])
rePointer = results;
//NSLog(@"results r: %i", r);
else
r = [indexPath row];
rePointer = rejects;
//NSLog(@"rejects r: %i", r);
NSString *noTxt = [[NSString alloc]initWithFormat:@"%i.", r+1];
CGSize boundingSize = CGSizeMake(35, 100);
UIFont *sysFont = [UIFont systemFontOfSize:12];
CGSize requiredSize = [noTxt sizeWithFont:sysFont constrainedToSize:boundingSize lineBreakMode:UILineBreakModeWordWrap];
CGFloat requiredHeight = requiredSize.height;
UILabel *numberLbl = (UILabel*)[cell viewWithTag:kNumberLblTag];
numberLbl.frame = CGRectMake(5, 5, 35, requiredHeight);
numberLbl.text = noTxt;
NSMutableString *amountTxt = [[NSMutableString alloc]initWithString:@"amount: "];
[amountTxt appendString:[NSString stringWithFormat:@"%@", [[rePointer objectAtIndex:r] objectForKey:@"amount"]]];
boundingSize = CGSizeMake(35, 100);
sysFont = [UIFont systemFontOfSize:12];
requiredSize = [amountTxt sizeWithFont:sysFont constrainedToSize:boundingSize lineBreakMode:UILineBreakModeWordWrap];
requiredHeight = requiredSize.height;
UILabel *amountLbl = (UILabel*)[cell viewWithTag:kamountLblTag];
amountLbl.frame = CGRectMake(5, 20, 35, requiredHeight);
amountLbl.text = amountTxt;
if ([[[rePointer objectAtIndex:r] objectForKey:@"count"] intValue] > 0)
NSString *mergedTxt = [[NSString alloc]initWithString:@"Count"];
boundingSize = CGSizeMake(35, 100);
sysFont = [UIFont systemFontOfSize:12];
requiredSize = [mergedTxt sizeWithFont:sysFont constrainedToSize:boundingSize lineBreakMode:UILineBreakModeWordWrap];
requiredHeight = requiredSize.height;
UILabel *mergeLbl = (UILabel*)[cell viewWithTag:kMergeLblTag];
mergeLbl.frame = CGRectMake(5, 50, 35, requiredHeight);
mergeLbl.text = mergedTxt;
[mergedTxt release];
else
UILabel *mergeLbl = (UILabel*)[cell viewWithTag:kMergeLblTag];
mergeLbl.frame = CGRectZero;
mergeLbl.text = @"";
NSString *type;
if (![[[rePointer objectAtIndex:r] objectForKey:@"type"] isEqualToString:@"NotSet"])
if ([[[rePointer objectAtIndex:r] objectForKey:@"type"] isEqualToString:@"[XYZ]"])
type = @"X";
else
int typeLength = [[[rePointer objectAtIndex:r] objectForKey:@"type"] length];
type = [[[rePointer objectAtIndex:r] objectForKey:@"type"] substringWithRange:NSMakeRange(1, typeLength-2)];
UILabel *typeLbl = (UILabel*)[cell viewWithTag:kTypeLblTag];
typeLbl.frame = CGRectMake(5, 65, 35, 20);
typeLbl.text = type;
else
UILabel *typeLbl = (UILabel*)[cell viewWithTag:kTypeLblTag];
typeLbl.frame = CGRectZero;
typeLbl.text = @"";
NSString *titleTxt = [[NSString alloc]initWithString:[[[rePointer objectAtIndex:r] objectForKey:@"h_title"]stringByTrimmingCharactersInSet: [NSCharacterSet whitespaceAndNewlineCharacterSet]]];
boundingSize = CGSizeMake(190, 1000);
sysFont = [UIFont systemFontOfSize:14];
requiredSize = [titleTxt sizeWithFont:sysFont constrainedToSize:boundingSize lineBreakMode:UILineBreakModeWordWrap];
requiredHeight = requiredSize.height;
CGFloat titleHeight = requiredHeight;
UILabel *titleLbl = (UILabel*)[cell viewWithTag:kTitleLblTag];
titleLbl.frame = CGRectMake(50, 5, 190, requiredHeight);
titleLbl.text = titleTxt;
[titleTxt release];
NSString *title2Txt = [[NSString alloc]initWithString:[[[rePointer objectAtIndex:r] objectForKey:@"title2"]stringByTrimmingCharactersInSet: [NSCharacterSet whitespaceAndNewlineCharacterSet]]];
sysFont = [UIFont systemFontOfSize:12];
requiredSize = [title2Txt sizeWithFont:sysFont constrainedToSize:boundingSize lineBreakMode:UILineBreakModeWordWrap];
requiredHeight = requiredSize.height;
UILabel *title2Lbl = (UILabel*)[cell viewWithTag:ktitle2LblTag];
title2Lbl.frame = CGRectMake(50, titleHeight + 10, 190, requiredHeight);
title2Lbl.text = title2Txt;
[title2Txt release];
/*
CGFloat height = [[[rePointer objectAtIndex:r] objectForKey:@"h_title"] sizeWithFont:[UIFont systemFontOfSize:14] constrainedToSize:CGSizeMake(190, 1000) lineBreakMode:UILineBreakModeWordWrap].height;
height += [[[rePointer objectAtIndex:r] objectForKey:@"title2"] sizeWithFont:[UIFont systemFontOfSize:12] constrainedToSize:CGSizeMake(190, 1000) lineBreakMode:UILineBreakModeWordWrap].height;
height += 20;
*/
cell.contentView.backgroundColor = clearColor;
cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
NSLog(@"cellForRowAtIndexPath");
/*
cell.backgroundView.frame = CGRectMake(0, 0, 320, height-1);
cell.backgroundView.backgroundColor = bgColor;
*/
return cell;
最后是 heightForRowAtIndexPath：
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
NSUInteger row = [indexPath row];
NSUInteger section = [indexPath section];
row += section*100;
NSUInteger rejectsIndex = [indexPath row];
if (row < [results count])
CGFloat height = [[[results objectAtIndex:row] objectForKey:@"h_title"] sizeWithFont:[UIFont systemFontOfSize:14] constrainedToSize:CGSizeMake(190, 1000) lineBreakMode:UILineBreakModeWordWrap].height;
height += [[[results objectAtIndex:row] objectForKey:@"title2"] sizeWithFont:[UIFont systemFontOfSize:12] constrainedToSize:CGSizeMake(190, 1000) lineBreakMode:UILineBreakModeWordWrap].height;
height += 20;
return MAX(90, height);
else
CGFloat height = [[[rejects objectAtIndex:rejectsIndex] objectForKey:@"h_title"] sizeWithFont:[UIFont systemFontOfSize:14] constrainedToSize:CGSizeMake(190, 1000) lineBreakMode:UILineBreakModeWordWrap].height;
height += [[[rejects objectAtIndex:rejectsIndex] objectForKey:@"title2"] sizeWithFont:[UIFont systemFontOfSize:12] constrainedToSize:CGSizeMake(190, 1000) lineBreakMode:UILineBreakModeWordWrap].height;
height += 20;
return MAX (90, height);
非常感谢您的建议！
【问题讨论】：
【参考方案1】：我认为您的代码过于复杂，因此效率低下。也许您应该考虑使用自定义表格视图单元格，它可以让您直接访问所有元素。
我还建议缓存可能很慢的尺寸测量值。
【讨论】：
嗯，我考虑过继承 UITableViewCell。但是我仍然必须每次都对单元格进行布局。那为什么会好很多呢？缓存尺寸测量值究竟是什么意思？ 我只是按照您的建议尝试对 UITableViewCell 进行子类化。但是，我的应用程序有时只是在显示 tableview 后没有响应。主要是当我在导航堆栈层次结构中来回走动时。 您计算所需的高度并一遍又一遍地设置元素的位置 - 但如果这真的是问题还不清楚。您可能需要使用仪器进行一些性能日志记录（进行一些滚动并查看大多数周期花费的位置）。 嗯，首先我必须一遍又一遍地计算尺寸。在此示例中可能没有任何意义，因为我将标签放置在固定位置。但在我的“真实代码”中，这是动态的，因此每次都必须重新计算和重置标签的位置和帧。但这似乎不是问题。滚动执行得很好。根据 Instruments 的说法，它也不占用太多内存。问题真的很奇怪。快速返回到 rootViewController 后，UITableViewController 显示但不再响应。【参考方案2】：因为您使用标签来标识单元格中的子视图。请注意一件事，不要使用 0 作为标签号，或者某些标签号与单元格的标签值相同。
viewWithTag: 方法将返回第一个带有标签号的子视图，如果单元格的标签与您想要的相同，它将返回单元格，而不是子视图。
Eiko 的建议是对的，您应该考虑使用自定义表格视图单元格。
【讨论】：
【参考方案3】：原来是 ios 的 bug。
【讨论】：
想详细说明一下？我知道已经有一段时间了，但是您应该分享您的发现以帮助其他正在寻找答案的人:-)以上是关于具有动态内容、动态布局和动态高度的 UITableViewCell的主要内容，如果未能解决你的问题，请参考以下文章
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