get size of string with font in cocoa touch

get_string_size.m

NSString *str = ...;
UIFont *font = [UIFont systemFontOfSize:12.0f];
NSDictionary<NSString *, id> *textAttributes = @{NSFontAttributeName: font};
CGRect rect = [str boundingRectWithSize:CGSizeMake(self.bounds.size.width, CGFLOAT_MAX) options:NSStringDrawingUsesLineFragmentOrigin attributes:textAttributes context:nil];

return rect.size.height;