自适应label

//自适应label
        self.contentLabel.numberOfLines = 0;
        CGSize contentsize = CGSizeMake(SCREEN_WIDTH - 2 * RP_MARGIN_W,2000);
        CGSize contentlabelsize = [self.contentLabel.text sizeWithFont:[UIFont systemFontOfSize:A6_v24] constrainedToSize:contentsize lineBreakMode:NSLineBreakByWordWrapping];
        self.contentLabel.frame = CGRectMake(RP_MARGIN_W, d9_v24 + d13_v24 * 2 + A4_v24 + A5_v24, SCREEN_WIDTH - 4 * RP_MARGIN_W, contentlabelsize.height );