我有一个UItableview，我使用heightForRowAtIndexPath和cellForRowAtIndexPath填充了数据。显然Apple让我在我的代码中做两次事情。
首先，我必须在heightForRowAtIndexPath中计算我的观点的大小（因为我必须制作它们），然后我必须再次制作它们，将它们添加到实际视图中。
我有一个非常复杂的视图，所以当你必须写两次时它看起来很难看。
有没有更好的方法来做到这一点？
更新
这是我的代码的样子。它不完全一样，但非常接近。为什么苹果让我写这两次？
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath{
NSLog(@"heightForRowAtIndexPath");
//Initiating strings
NSString *headlineString;
NSString *subHeadlineString;
NSString *bylineString;
if (global.magazine.issues.count==0) {
return 45;
}else if(indexPath.section == global.magazine.issues.count+1) {
//Finding the right issue and article for this row
Issue *issue = [global.magazine.issues objectAtIndex:global.magazine.issues.count-1];
//Creating the headline
headlineString = [NSString stringWithFormat:@"<span class='bold_style'>FOREWORD</span>"];
//Creating the subHeadline
subHeadlineString = [NSString stringWithFormat:@"%@", [issue.magazine_foreword substringToIndex:100]];
//Creating byline
bylineString = [[NSString stringWithFormat:@"<span class='ital_style'>By %@</span>", issue.magazine_byline] capitalizedString];
}else{
//Finding the right issue and article for this row
Issue *issue = [global.magazine.issues objectAtIndex:indexPath.section-1];
Article *article = [issue.articles objectAtIndex:indexPath.row];
//Creating the headline
headlineString = [NSString stringWithFormat:@"<span class='bold_style'>%@</span>", [article.title uppercaseString]];
//Creating the subHeadline
subHeadlineString = [NSString stringWithFormat:@"%@", [article.main_text substringToIndex:100]];
//Creating byline
bylineString = [NSString stringWithFormat:@"<span class='ital_style'>By %@</span>", article.byline];
}
//Creating the labels
NMCustomLabel *headline = [global.label headLineLabelWithString:headlineString fromTop:30 withWidth:global.screenWidth-60];
NMCustomLabel *subHeadline = [global.label subHeadlineLabelWithString:subHeadlineString fromTop:30+headline.height+10 withWidth:global.screenWidth-60];
NMCustomLabel *byline = [global.label articleBylineLabelWithString:bylineString fromTop:30+headline.height+10+subHeadline.height+10 withWidth:global.screenWidth-60];
//Setting the height of the row
return 30+headline.height+10+subHeadline.height+10+byline.height+30;
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
NSLog(@"cellForRowAtIndexPath");
//Preparing the cell
static NSString *CellIdentifier = @"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
if (cell == nil) {
cell = [[UITableViewCell alloc]
initWithStyle:UITableViewCellStyleDefault
reuseIdentifier:CellIdentifier];
}
//Removing former text views
for (UIView *subview in [cell subviews]) {
if (subview.tag == 21 || subview.tag == 22 || subview.tag == 23) [subview removeFromSuperview];
}
//Removing and setting tableview border
[[cell viewWithTag:30] removeFromSuperview];
UIView *rightBorder = [[UIView alloc] initWithFrame:CGRectMake(cell.width-1, 0, 1, cell.height)];
rightBorder.backgroundColor = global.lightGrey;
rightBorder.tag = 30;
[cell addSubview:rightBorder];
//Setting the seletion background color on the cells
UIView *bgColorView = [[UIView alloc] init];
bgColorView.backgroundColor = global.extraLightGrey;
cell.selectedBackgroundView = bgColorView;
if (global.magazine.issues.count==0) {
return cell;
}else if (indexPath.section-1 == global.magazine.issues.count) {
//Finding the right issue and article for this row
Issue *issue = [global.magazine.issues objectAtIndex:global.magazine.issues.count-1];
//Creating the headline
NSString *headlineString = [NSString stringWithFormat:@"<span class='bold_style'>FOREWORD</span>"];
NMCustomLabel *headline = [global.label headLineLabelWithString:headlineString fromTop:30 withWidth:global.screenWidth-60];
headline.tag = 21;
[cell addSubview:headline];
//Creating the subHeadline
NSString *subHeadlineString = [[NSString stringWithFormat:@"%@", issue.magazine_foreword] substringToIndex:100];
NMCustomLabel *subHeadline = [global.label subHeadlineLabelWithString:subHeadlineString fromTop:30+headline.height+10 withWidth:global.screenWidth-60];
subHeadline.tag = 22;
[cell addSubview:subHeadline];
//Creating byline
NSString *bylineString = [[NSString stringWithFormat:@"<span class='ital_style'>By %@</span>", issue.magazine_byline] capitalizedString];
NMCustomLabel *byline = [global.label articleBylineLabelWithString:bylineString fromTop:30+headline.height+10+subHeadline.height+10 withWidth:global.screenWidth-60];
byline.tag = 23;
[cell addSubview:byline];
}else{
//Finding the right issue and article for this row
Issue *issue = [global.magazine.issues objectAtIndex:indexPath.section-1];
Article *article = [issue.articles objectAtIndex:indexPath.row];
//Creating the headline
NSString *headlineString = [NSString stringWithFormat:@"<span class='bold_style'>%@</span>", [article.title uppercaseString]];
NMCustomLabel *headline = [global.label headLineLabelWithString:headlineString fromTop:30 withWidth:global.screenWidth-60];
headline.tag = 21;
[cell addSubview:headline];
//Creating the subHeadline
NSString *subHeadlineString = [NSString stringWithFormat:@"%@", [article.main_text substringToIndex:100]];
NMCustomLabel *subHeadline = [global.label subHeadlineLabelWithString:subHeadlineString fromTop:30+headline.height+10 withWidth:global.screenWidth-60];
subHeadline.tag = 22;
[cell addSubview:subHeadline];
//Creating byline
NSString *bylineString = [[NSString stringWithFormat:@"<span class='ital_style'>By %@</span>", article.byline] capitalizedString];
NMCustomLabel *byline = [global.label articleBylineLabelWithString:bylineString fromTop:30+headline.height+10+subHeadline.height+10 withWidth:global.screenWidth-60];
byline.tag = 23;
[cell addSubview:byline];
}
return cell;
}
答案 0 :(得分：2)
最简单的解决方案是遵循DRY原则，并将高度添加为您用作数据源的对象的属性，或者向视图控制器添加方法，例如：
-(CGFloat)calculateHeightForHeadline:(NSString*)headline andSubHeadline:(NSString*)subHeadline andByLine:(NSString*)byLine
然后至少你只在一个地方有计算代码。
或者，您可以从您的cellForRowAtIndexPath方法
中调用[tableView heightForRowAtIndexPath:indexPath]
答案 1 :(得分：2)
你必须做两次因为表视图在绘制任何东西之前需要知道它的总高度 - 所以它在调用任何单元格方法之前调用每行的height方法。根据您当前的代码，根据行数，您可能会在表格出现之前稍微延迟 - 乐器会告诉您这是您花费时间的高度方法。
我不知道您自定义标签类的作用，但您可以通过使用字符串或属性字符串绘制和大小计算UIKit extensions来计算高度，而无需创建视图（这是昂贵的），这是为了这个目的而创建的。
答案 2 :(得分：0)
heightForRowAtIndexPath
将为您的所有行调用。此委托方法返回行的高度。由于您的设计需要根据条件不同的高度。不幸的是，每次创建行之前，您都必须计算行高。这就像我们在绘制行之前决定什么是它的高度。
有一种方法可以避免这种情况。但我不建议你去做。因为它会改变UITableView的设计。你可以做的是你可以从你拥有的所有条件中决定你行的最大高度。例如。我们将其视为100像素。然后你可以绘制其余的细胞。但是，如果您的行中的任何行小于100像素，则会留下空白区域。它看起来很毛茸茸。
基本上，为了满足您的要求，您必须两次这样做。别无选择： - （
答案 3 :(得分：0)
我想知道，为什么要在heightForRowAtIndexpath中创建自定义标签？为什么不用sizeWithFont:或这样的方法计算文本的大小？我认为这是计算行高的更好方法。祝你好运！