1.

CGSize titleSize = [str boundingRectWithSize:CGSizeMake(245.0, MAXFLOAT) options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName:[UIFont systemFontOfSize:13]} context:nil].size;

 

2.

// screenWidth

    CGFloat screenWidth = [UIScreen mainScreen].bounds.size.width;

    

    CGRect tempFrame =

    [_title boundingRectWithSize:CGSizeMake(screenWidth - LABEL_MARGIN * 2, CGFLOAT_MAX)

                         options:NSStringDrawingUsesLineFragmentOrigin

                      attributes:@{NSFontAttributeName:TITLE_FONT}

                         context:nil];