iOS 判断是否开启系统通知权限

if (@available(iOS 10 , *)){
    weakify(self);
    [[UNUserNotificationCenter currentNotificationCenter] getNotificationSettingsWithCompletionHandler:^(UNNotificationSettings * _Nonnull settings) {
        if (settings.authorizationStatus == UNAuthorizationStatusDenied){
            // 没权限
        }
    }];
}else{
    UIUserNotificationSettings * setting = [[UIApplication sharedApplication] currentUserNotificationSettings];
    if (setting.types == UIUserNotificationTypeNone) {
        // 没权限
    }
}