sizeWithFont:constrainedToSize:lineBreakMode: deprecated in iOS7

Question

I'm updating my app to iOS 7 and finally got it, but there's one thing I can't find a solution for.

In Xcode 4 I used the following method:

#define FONT_SIZE 14.0f
#define CELL_CONTENT_WIDTH 280.0f
#define CELL_CONTENT_MARGIN 10.0f


- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath; {
    NSString *text = [textA objectAtIndex:[indexPath row]];

    CGSize constraint = CGSizeMake(CELL_CONTENT_WIDTH - (CELL_CONTENT_MARGIN * 2), 20000.0f);

    CGSize size = [text sizeWithFont:[UIFont systemFontOfSize:FONT_SIZE] constrainedToSize:constraint lineBreakMode:NSLineBreakByWordWrapping];

    CGFloat height = MAX(size.height, 28.0f);

    return height + (CELL_CONTENT_MARGIN * 2);
}

But I'll get an error when using it in iOS 7:

Use -boundingRectWithSize:options:attributes:context:

I don't know how to convert my earlier version to this new method and it would be great if anyone could help me. Thanks in advance.

Answer 1

sizeWithFont methods were deprecated in iOS7. You should use boundingRectWithSize instead. If you also need to support prior iOS versions then you can use following code:

CGSize size = CGSizeZero;

if ([label.text respondsToSelector: @selector(boundingRectWithSize:options:attributes:context:)] == YES) {
    size = [label.text boundingRectWithSize: constrainedSize options: NSStringDrawingUsesLineFragmentOrigin
                                 attributes: @{ NSFontAttributeName: label.font } context: nil].size;
} else {
    size = [label.text sizeWithFont: label.font constrainedToSize: constrainedSize lineBreakMode: UILineBreakModeWordWrap];
}

Answer 2

If you're only supporting ios6 and later, you can convert your NSStrings to NSAttributedStrings and use NSAttributedString's boundingRectWithSize:options:context:.

Something that looked like this before:

CGSize size = [text sizeWithFont:font
               constrainedToSize:(CGSize){maxWidth, CGFLOAT_MAX}];

Could be easily converted to this and work in both ios6 and ios7:

NSAttributedString *attributedText =
    [[NSAttributedString alloc]
        initWithString:text
        attributes:@
        {
            NSFontAttributeName:    font
        }];
CGRect rect = [attributedText boundingRectWithSize:(CGSize){maxWidth, CGFLOAT_MAX}
                                           options:NSStringDrawingUsesLineFragmentOrigin
                                           context:nil];
CGSize size = rect.size;

As a side note, the benefit of doing things this way is so your text sizing in ios6 is now thread-safe. The old methods of sizeWithFont:... belonged to UIStringDrawing, which would crash if you ran sizeWithFont:... on two threads at the same time. In ios6, new NSStringDrawing functions for NSAttributedStrings were exposed and the boundingRectWithSize:... function is thread safe. I'm guessing this is why in ios7, the old sizeWithFont:... functions were deprecated.

Please note the documentation mentions:

In iOS 7 and later, this method returns fractional sizes (in the size component of the returned CGRect); to use a returned size to size views, you must use raise its value to the nearest higher integer using the ceil function.

So to pull out the calculated height or width to be used for sizing views, I would use:

CGFloat height = ceilf(size.height);
CGFloat width  = ceilf(size.width);