App.vue onLaunch 调用methods函数为 is not a function

分类：uni-app

移动APP

第一次使用小白求助，app 启动时候调用methods函数会提示 is not a function

hx.version: 2.8.13.20200927

    onLaunch() {  
            console.log('on Launch', this.isIos())  
            plus.screen.lockOrientation('portrait-primary')  
        },  
methods: {  

            isIos() {  
                return systemInfo.platform !== 'android'  
            }  
}

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