Calculate UILabel height for text with different languages and emojis in Objective-C

Question

I need to calculate the frame size for given text that may be in english/emoji/other languages.

The way I did it was:

NSMutableParagraphStyle *style = [[NSParagraphStyle defaultParagraphStyle] mutableCopy];
[style setLineBreakMode:NSLineBreakByWordWrapping];
NSDictionary *attributes = @{NSFontAttributeName: [UIFont systemFontOfSize:fontSize], NSParagraphStyleAttributeName: style};
CGSize rect = [text boundingRectWithSize:CGSizeMake(containerWidth, CGFLOAT_MAX)
                               options:NSStringDrawingUsesLineFragmentOrigin| NSStringDrawingUsesFontLeading
                            attributes:attributes
                               context:nil].size;

It works fine as long as I do not use emoji. It seems that the emoji line height/font size is different than regular fonts.

I saw that people tried solving it in different ways such as: http://youbbe.xyz/issue/4987325/ios-emoji-messed-up-in-uilabel

This solution works for emojis but not for English/other fonts.

See example image:

As you can see, just text is calculated fine (first box) but text+emoji is not calculated correctly (second box).

I'm really surprised that there is no easy solution for this problem. Your help is much appreciated.

Answer 1

With a UILabel you can simply say:

CGSize size = [label sizeThatFits:CGSizeMake(containerWidth, CGFLOAT_MAX)];

Have you tried this? I don't think emoji have a different line height, but rather they typically take up the entire line height.

You can just say [label sizeToFit]; and then get the size from the frame, (e.g. CGSize size = label.frame.size;). This seems the most consistently accurate way of getting the right size for different font sizes.

There is some code here that you can copy and paste into a playground and see the different results.

Answer 2

A possible solution is set text with attribute string and specify paragraph style

NSMutableParagraphStyle *paragraphStyle = [[NSMutableParagraphStyle alloc] init];
paragraphStyle.lineSpacing = 5;
paragraphStyle.lineHeightMultiple = 1.1;
paragraphStyle.maximumLineHeight = 16;

maximumLineHeight can limit height of line which has emoji in it.