iOS 6 / iOS 7 universal NSString size calculation.

gistfile1.m

NSString *str = <#some string#>;
CGSize size;
CGSize maxSize = CGSizeMake(<#width#>, <#height#>);
UIFont *font = <#font#>;
if ([str respondsToSelector:@selector(boundingRectWithSize:options:attributes:context:)]) {
    NSMutableParagraphStyle *style = [[NSMutableParagraphStyle alloc] init];
    [style setLineBreakMode:<#Line break mode#>];
    [style setAlignment:<#String alignment#>];
    NSDictionary *attributes = @{ NSFontAttributeName:font,
                                  NSParagraphStyleAttributeName:style
                                };
    size = [str boundingRectWithSize:maxSize options:NSStringDrawingUsesFontLeading|NSStringDrawingUsesLineFragmentOrigin attributes:attributes context:nil].size;
}
else {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
    size = [str sizeWithFont:font constrainedToSize:maxSize lineBreakMode:<#Line break mode#>];
#pragma clang diagnostic pop
}

why it can not calculate string like @"你的电脑中毒了，赶紧关机！！！" ? when width is 300, it return 15.05 for height value and in the view the string display to : 你的电脑中毒了，赶紧{\n}关机！！！, there is a unexpect "\n"