MeasureText.m

RCT_EXPORT_METHOD(measureTextRect:(NSString *)string withWidth:(double)width withFontName:(NSString *)fontName andFontSize:(double)fontSize andCallback:(RCTResponseSenderBlock)callback)
{
  UIFont *font = [UIFont fontWithName:fontName size:fontSize];
  NSDictionary *attributes = [NSDictionary dictionaryWithObjectsAndKeys:font, NSFontAttributeName, nil];

  CGRect rect = [string boundingRectWithSize:CGSizeMake(width, CGFLOAT_MAX)
                                     options:NSStringDrawingUsesLineFragmentOrigin
                                  attributes:attributes
                                     context:nil];
  
  callback(@[
    @{
      @"height": [NSNumber numberWithFloat:rect.size.height],
      @"width": [NSNumber numberWithFloat:rect.size.width],
    }
  ]);
}