//計算高度
CGFloat detailLabHeight=[NSString heightForString:bra fontSize:14 andWidth:(MB_DEVICE_WIDTH-2*30-20)];
+ (CGFloat) heightForString:(NSString *)value fontSize:(CGFloat)fontSize andWidth:(CGFloat)width
{
CGSize sizeToFit = [value sizeWithFont:[UIFont systemFontOfSize:fontSize] constrainedToSize:CGSizeMake(width, CGFLOAT_MAX) lineBreakMode:NSLineBreakByWordWrapping];//此處的換行類型（lineBreakMode）可根據自己的實際情況進行設置
return sizeToFit.height;
}