iOS，在onshow里面设置setKeepScreenOn为ture，点击按钮跳转相册，在相册里面会熄屏。

代码如下

onShow() {

wx.setKeepScreenOn({

keepScreenOn: true

})  

},

onVideoExtractionClick() {

wx.chooseMedia({

count: 1,

mediaType: ['video'],

sourceType: ['album'],

success(res) {

console.log('chooseMedia', res);

}

})

},