app判断通知权限是否开启，前往系统设置页面开关通知权限

来源：https://ext.dcloud.net.cn/plugin?id=789

// 判断通知权限是否开启  
function isOn() {  
    // #ifdef APP-PLUS  
    if (plus.os.name == 'Android') {  
        var main = plus.android.runtimeMainActivity();  
        var NotificationManagerCompat = plus.android.importClass("android.support.v4.app.NotificationManagerCompat");  
        if (NotificationManagerCompat == null) { NotificationManagerCompat = plus.android.importClass("androidx.core.app.NotificationManagerCompat"); }  
        var areNotificationsEnabled = NotificationManagerCompat.from(main).areNotificationsEnabled();  
        return areNotificationsEnabled;  
    } else if (plus.os.name == 'iOS') {  
        var isIosOn = undefined;  
        var types = 0;  
        var app = plus.ios.invoke('UIApplication', 'sharedApplication');  
        var settings = plus.ios.invoke(app, 'currentUserNotificationSettings');  
        if (settings) {  
            types = settings.plusGetAttribute('types');  
            plus.ios.deleteObject(settings);  
        } else {  
            types = plus.ios.invoke(app, 'enabledRemoteNotificationTypes');  
        }  
        plus.ios.deleteObject(app);  
        isIosOn = (0 != types);  
        return isIosOn;  
    }  
    // #endif  
}  

// 前往系统设置页面开启或关闭通知权限  
function switchPushPermissions () {  
    // #ifdef APP-PLUS  
    let title = isOn() ? "通知权限关闭提醒" : "通知权限开启提醒";  
    let content = isOn() ? "通知权限已开启，是否前往设置关闭？" : "您还没有开启通知权限，无法接受到消息通知，是否前往设置？";  
    // 打开安卓系统设置页面  
    let openAndroidSetting = () => {  
        var main = plus.android.runtimeMainActivity();  
        var pkName = main.getPackageName();  
        var uid = main.getApplicationInfo().plusGetAttribute("uid");  
        var Intent = plus.android.importClass('android.content.Intent');  
        var Build = plus.android.importClass("android.os.Build");  
        //android 8.0引导    
        if (Build.VERSION.SDK_INT >= 26) {  
            var intent = new Intent('android.settings.APP_NOTIFICATION_SETTINGS');  
            intent.putExtra('android.provider.extra.APP_PACKAGE', pkName);  
        } else if (Build.VERSION.SDK_INT >= 21) { //android 5.0-7.0    
            var intent = new Intent('android.settings.APP_NOTIFICATION_SETTINGS');  
            intent.putExtra("app_package", pkName);  
            intent.putExtra("app_uid", uid);  
        } else { //(<21)其他--跳转到该应用管理的详情页    
            intent.setAction(Settings.ACTION_APPLICATION_DETAILS_SETTINGS);  
            var uri = Uri.fromParts("package", mainActivity.getPackageName(), null);  
            intent.setData(uri);  
        }  
        // 跳转到该应用的系统通知设置页    
        main.startActivity(intent);  
    }  
    // 打开苹果系统设置页面  
    let openIOSSetting = () => {  
        var app = plus.ios.invoke('UIApplication', 'sharedApplication');  
        var setting = plus.ios.invoke('NSURL', 'URLWithString:', 'app-settings:');  
        plus.ios.invoke(app, 'openURL:', setting);  
        plus.ios.deleteObject(setting);  
        plus.ios.deleteObject(app);  
    }  
    // 弹窗提醒开通或关闭权限，点击确认后，跳转到系统设置页面进行设置  
    uni.showModal({  
        title: title,  
        content: content,  
        showCancel: true,  
        confirmColor: "#ff903f",  
        success: (res) => {  
            if (res.confirm) {  
                if (plus.os.name == 'Android') {  
                    openAndroidSetting();  
                } else if (plus.os.name == 'iOS') {  
                    openIOSSetting();  
                }  
            }  
        }  
    })  
    // #endif    
}  

export default {  
    isOn,  
    switchPushPermissions  
};