需求：移动端只轮播一张图片，PC端轮播三张图片。使用直接修改swiper属性的方式需要手动刷新页面才能达到效果，
灰常恶心。。。。于是想到切换窗口时先销毁swiper再重新实例化swiper,,问题解决。。

let news_swiper = new Swiper('.news_swiper', {
    slidesPerView: 3,
    spaceBetween: 30,
    slidesPerGroup: 3,
    loop: false,
    observer: true,
    observeSlideChildren: true,
    loopFillGroupWithBlank: true,
    navigation: {
        nextEl: '.swiper-button-next',
        prevEl: '.swiper-button-prev',
    },
    autoplay: true,
    /* observer:true,//修改swiper自己或子元素时，自动初始化swiper
     observeParents:false,//修改swiper的父元素时，自动初始化swiper
     onSlideChangeEnd: function(swiper){
         swiper.update();
         news_swiper.startAutoplay();// 重新开始自动切换；
         news_swiper.reLoop();
     }*/
});

function newsSwiper_mobile() {
    let $win = $(window).width();
    if ($win > 768) {
        news_swiper.destroy(true,true);
        news_swiper = new Swiper('.news_swiper', {
            slidesPerView: 3,
            spaceBetween: 30,
            slidesPerGroup: 3,
            loop: false,
            loopFillGroupWithBlank: true,
            navigation: {
                nextEl: '.swiper-button-next',
                prevEl: '.swiper-button-prev',
            },
            autoplay: true,
        });
    } else {
        news_swiper.destroy(true,true);
        news_swiper = new Swiper('.news_swiper', {
            slidesPerView: 1,
            spaceBetween: 30,
            slidesPerGroup: 1,
            loop: false,
            loopFillGroupWithBlank: true,
            navigation: {
                nextEl: '.swiper-button-next',
                prevEl: '.swiper-button-prev',
            },
            autoplay: true,
        });
    }
}

注意：若不考虑页面刷新问题，则动态修改属性是:   

news_swiper.params.slidesPerView = 3;