-[__NSCFString boundingRectWithSize:options:attributes:context:]: 无法识别的选择器发送到实例

Question

@interface PromotionsListViewController : UITableViewController 
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = @"PromotionCell";
PromotionCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
    cell = [[PromotionCell alloc] init];
}

// Configure the cell...
Promotion *promotion = [self.promotionList objectAtIndex:indexPath.row];

[cell.imgView setImageWithURL:[NSURL URLWithString:promotion.imageURL] placeholderImage:[UIImage imageNamed:@""]];
cell.lblTitle.text = promotion.promotionTitle;

return cell;
}
@interface PromotionCell : UITableViewCell

@property(nonatomic, strong) UIImageView *imgView;
@property(nonatomic, strong) UILabel *lblTitle;

@end
- (void)layoutSubviews {

if (self.lblTitle.text) {

    CGSize maxsize = CGSizeMake(300, CGFLOAT_MAX);
    NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
    paragraphStyle.lineBreakMode = NSLineBreakByWordWrapping;

    CGRect calculateRect = [_lblTitle.text boundingRectWithSize:maxsize options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName:_lblTitle.font, NSParagraphStyleAttributeName:paragraphStyle.copy} context:nil];

    _lblTitle.frame = CGRectMake(_lblTitle.frame.origin.x, 300 - calculateRect.size.height - 5, _lblTitle.frame.size.width, calculateRect.size.height);

} else {
    _lblTitle.frame = CGRectZero;
}
}
- (UILabel *)lblTitle {

if (!_lblTitle) {

    _lblTitle = [[UILabel alloc] initWithFrame:CGRectMake(10, 250, 300, 50)];
    _lblTitle.font = [UIFont boldSystemFontOfSize:22.0f];
    _lblTitle.numberOfLines = 0;
    _lblTitle.lineBreakMode = NSLineBreakByWordWrapping;
    [self.contentView addSubview:_lblTitle];
}
return _lblTitle;
}

谁能告诉我我做错了什么？我希望我的问题很清楚..

Answer 1

我也有这个问题。原来boundingRectWithSize: 有两种类似的方法。一种用于NSString，一种用于NSAttributedString。

以下 NSAttributedString 可用于 iOS 6 及更高版本：

- (CGRect)boundingRectWithSize:(CGSize)size options:(NSStringDrawingOptions)options context:(NSStringDrawingContext *)context

另一个 NSString 方法（您当前正在使用）仅在 iOS 7 上可用：

- (CGRect)boundingRectWithSize:(CGSize)size options:(NSStringDrawingOptions)options attributes:(NSDictionary *)attributes context:(NSStringDrawingContext *)context

因此，只需在属性字符串上调用 boundingRectWithSize: 方法而不需要额外的 Attributes: 字段，它就可以在 iOS 6 上正常工作。