wx.canvasToTempFilePath({

    canvasId: ‘myCanvas’,

    success: function (res) {

        var imgSrc = res.tempFilePath;

        wx.saveImageToPhotosAlbum({

            filePath: imgSrc,

            success(res){

                wx.showModal({

                title: ‘’,

                content: ‘保存成功，请到相册查看’,

                showCancel:false

                })

            }

        })

    }

})

接口是这个    机型iphone7plus  系统ios11.1.1