我希望UITableView
的行高能够响应用户首选文本大小的更改。例如,当首选文本大小增加时,我希望按比例增加行高。到目前为止,我拥有的是:
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
[self.tableView reloadData];
// observe when user changes preferred text size
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(preferredContentSizeChanged:) name:UIContentSizeCategoryDidChangeNotification object:nil];
}
- (void)preferredContentSizeChanged:(NSNotification *)notification
{
[self.tableView reloadData];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *cellID = @"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellID forIndexPath:indexPath];
// leverage Text Kit's Dynamic Type
cell.textLabel.font = [UIFont preferredFontForTextStyle:UIFontTextStyleHeadline];
cell.textLabel.text = @"All work and no play...";
return cell;
}
那么,计算反映用户首选文本大小的行高的最佳方法是什么呢?
我最近完成了这项工作,发现它非常简单。您应该在iOS7中使用新的boundingRectWithSize:options:attributes:context
方法,而不是使用sizeWithFont:
。
像往常一样设置表格视图单元格,并在文本标签上指定preferredFontForTextStyle:
,如下所示:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:TableViewCellIdentifier forIndexPath:indexPath];
//set your table view cell content here
[[cell textLabel] setText:@"Lorem ipsum dolour sit amet."];
[[cell textLabel] setNumberOfLines:0];
[[cell textLabel] setLineBreakMode:NSLineBreakByWordWrapping];
[[cell textLabel] setFont:[UIFont preferredFontForTextStyle:UIFontTextStyleBody]];
return cell;
}
然后,为了正确确定文本标签的大小,评估boundingRectWithSize:options:attributes:context
以计算所需的高度。
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
//add your table view cell content here
NSString *string = @"Lorem ipsum dolor sit amet.";
NSDictionary *attributes = @{NSFontAttributeName: [UIFont preferredFontForTextStyle:UIFontTextStyleBody]};
CGRect frame = [string boundingRectWithSize:CGSizeMake(CGRectGetWidth(tableView.bounds), CGFLOAT_MAX) options:(NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading) attributes:attributes context:nil];
return ceilf(CGRectGetHeight(frame);
}
您可能还想将您的表视图单元格划分为子类,以侦听UIContentSizeCategoryDidChangeNotification
通知,当用户在Settings.app 中更改其首选项时,您可以更新您的UI
- (void)contentSizeCategoryDidChangeNotificationHandler:(NSNotification *)notification
{
[[self textLabel] setFont:[UIFont preferredFontForTextStyle:UIFontTextStyleBody]];
}
如果您需要在文本标签周围添加额外的填充,您可以定义一个常量值,如
static CGFloat const TableViewCellPadding = 10.0;
有了这个,您可以在tableView:heightForRowAtIndexPath:
返回的值上添加一个常数值
return (ceilf(CGRectGetHeight(frame) + TableViewCellPadding);
或者您可以插入从boundingRectWithSize:options:attributes:context
返回的帧,如下所示:
CGRect frame = [string boundingRectWithSize:CGSizeMake(CGRectGetWidth(tableView.bounds), CGFLOAT_MAX) options:(NSStringDrawingUsesLineFragmentOrigin | NSStringDrawingUsesFontLeading) attributes:attributes context:nil];
frame = CGRectInset(frame, 0.0, TableViewCellPadding);
使用此方法:
- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
NSString *fieldLabel = labelCell.textLabel.text;
CGSize textSize = [fieldLabel sizeWithFont:[UIFont fontWithName:@"Georgia" size:17.0f] constrainedToSize:CGSizeMake([UIScreen mainScreen].bounds.size.width-20, MAXFLOAT) lineBreakMode:NSLineBreakByWordWrapping];
float newHeight = textSize.height+22.0f;
return newHeight;
}
将以下代码添加到cellForRowAtIndexPath
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *cellID = @"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellID forIndexPath:indexPath];
UILabel *lblfield=[[UILabel alloc] init];
NSString *fieldLabel=[NSString stringWithFormat:@"%@",labelCell.textLabel.text];
CGSize textSize = [fieldLabel sizeWithFont:[UIFont fontWithName:@"Georgia" size:17.0f] constrainedToSize:CGSizeMake([UIScreen mainScreen].bounds.size.width-20, MAXFLOAT) lineBreakMode:NSLineBreakByWordWrapping];
float newHeight = textSize.height+22.0f;
lblfield.frame=CGRectMake(10, 0, [UIScreen mainScreen].bounds.size.width, newHeight);
lblfield.backgroundColor=[UIColor clearColor];
lblfield.text=strusername;
[cell addSubview:lblfield];
return cell;
}