方法: 

//预览图片 pic可传单个图片地址字符串 或 图片数组(带index)
previewPic: function(pic, index) {
	if (!pic) return;
	if (index == undefined) {
		let array = [];
		array.push(pic);
		uni.previewImage({
			urls: array,
			current: array[0]
		});
	} else {
		uni.previewImage({
			urls: pic,
			current: index
		});
	}
},

调用:

1.字符串形式:

previewPic('https://xxxx.png')

2.数组形式: 

previewPic(['https://xxxx1.png', 'https://xxxx2.png'], 0)