How to get NSString size when NSString includes emojis?

问题

I am currently using

- (CGSize)sizeWithFont:(UIFont *)font constrainedToSize:(CGSize)size lineBreakMode:(UILineBreakMode)lineBreakMode

to get the size of an NSString. However, when that string includes emojis, it seems to calculate the size for the literal unicode character rather than taking into account the size of the emoji itself, rendering the returned size incorrect.

How do I correctly get the size of the string with emoji characters, as it will appear in a uilabel?

回答1:

The NSString is not presenting the emoji, it's representing a string, so the sizeWithFont will only account for the string.

I would use:

CGRect labelFrame = label.frame;  
labelFrame.size = [label sizeThatFits:CGSizeMake(100, 9999)];  
[label setFrame:labelFrame]; 

or

//Alternatively  
[label sizeToFit];

Bare in mind that sizeToFit calls the sizeThatFits: method, so in terms of just setting the label to the right height, sizeThatFits: is quicker, and much easier on the eye.

回答2:

I struggled with this same thing for a while, attempting multiple solutions including the accepted answer, which did not work for me. I solved this by creating an NSAttributed String with the text, then using the NSAttributedString method boundingRectWithSize:options:context: to get the size of the string.

NSString *text = //some text
CGFloat maxSize = //text size constraints

NSAttributedString *attributedString = [[NSAttributedString alloc] initWithString:text
                                                                       attributes:@{NSFontAttributeName : font
                                                                                    }];

CGRect boundingRect = [attributedString boundingRectWithSize:maxSize options:NSStringDrawingUsesLineFragmentOrigin context:nil];
CGSize fitSize = boundingRect.size;

来源：https://stackoverflow.com/questions/15965525/how-to-get-nsstring-size-when-nsstring-includes-emojis