1

我有一个UItableview，我正在用数据填充它，使用heightForRowAtIndexPathand cellForRowAtIndexPath。显然苹果让我在我的代码中做两次事情。

首先，我必须计算我的视图的大小（为此我必须制作它们）heightForRowAtIndexPath，然后我必须再次制作它们，以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​​，它看起来很丑。

难道没有更好的方法来做到这一点吗？

更新

这就是我的代码的外观。它不完全一样，但非常接近。为什么苹果让我写两次？

- (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;
}
4

4 回答 4

2

最简单的解决方案是遵循 DRY 原则，或者添加高度作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

那么至少你在一个地方只有计算代码。

或者，您可以[tableView heightForRowAtIndexPath:indexPath]从 cellForRowAtIndexPath 方法调用

于 2013-02-15T07:19:22.800 回答
2

您必须这样做两次，因为表格视图需要在绘制任何内容之前知道它的总高度 - 因此它在调用任何单元格方法之前为每一行调用 height 方法。使用您当前的代码，根据行数，您可能会在表格出现之前遇到轻微的延迟 - 仪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做了什么，但您可以通过使用字符串或属性字符串绘图和大小计算UIKit 扩展来计算高度而无需创建视图（这很昂贵） ，这些扩展是为此精确创建的目的。

于 2013-02-15T07:20:04.403 回答
0

我想知道，您为什么要在 中创建自定义标签heightForRowAtIndexpath？你为什么不直接用sizeWithFont:或者这样的方法来计算文本的大小呢？我认为这将是计算行高的更好方法。祝你好运！

于 2013-02-15T08:11:09.100 回答
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为每行提供不同的高度。不幸的是，每次创建行之前，您都必须计算行高。就像我们在绘制行之前决定它的高度一样。

有一种方法可以避免这种情况。但我不会建议你去做。因为它会改变你的设计UITableView。您可以做的是，您可以从所有可能的条件中确定行的最大高度。例如。让我们将其视为 100 像素。然后你可以画出你剩下的单元格。但是，如果您的任何行小于 100 像素，则会留下空白空间。而且它看起来很蓬松。

基本上，要满足您的要求，您必须这样做两次。没有其他选择:-(

于 2013-02-15T06:33:39.990 回答