计算label的宽度
+(CGFloat)getLabelWidth:(NSString *)textString defautWidth:(float)defautWidth defautHeight:(float)defautHeight fontSize:(int)fontSize
{
CGSize size = CGSizeMake(defautWidth,defautHeight);
CGSize labelsize;
#if __IPHONE_OS_VERSION_MAX_ALLOWED >= __IPHONE_7_0
NSDictionary * dic = [NSDictionary dictionaryWithObjectsAndKeys:[UIFont systemFontOfSize:fontSize] ,NSFontAttributeName,nil];
labelsize = [textString boundingRectWithSize:size options:NSStringDrawingUsesLineFragmentOrigin attributes:dic context:nil].size;
#else
labelsize = [textString sizeWithFont:font constrainedToSize:size lineBreakMode:NSLineBreakByWordWrapping];
#endif
return labelsize.width;
}
