关于 iOS 13 CNCopyCurrentNetworkInfo 不再返回Wi-Fi SSID and BSSID

写在前面

最近收到了苹果的邮件，说获取WiFi SSID的接口CNCopyCurrentNetworkInfo 不再返回SSID的值。不仔细看还真会被吓一跳，对物联网的相关APP简直是炸弹。仔细看邮件还好说明了可以先获取用户位置权限才能返回SSID。

Dear Developer,

As we announced at WWDC19, we're making changes to further protect user privacy and prevent unauthorized location tracking. Starting with iOS 13, the CNCopyCurrentNetworkInfo API will no longer return valid Wi-Fi SSID and BSSID information. Instead, the information returned by default will be: 

SSID: “Wi-Fi” or “WLAN” (“WLAN" will be returned for the China SKU)
BSSID: "00:00:00:00:00:00" 

If your app is using this API, we encourage you to adopt alternative approaches that don’t require Wi-Fi or network information. Valid SSID and BSSID information from CNCopyCurrentNetworkInfo will still be provided to VPN apps, apps that have used NEHotspotConfiguration to configure the current Wi-Fi network, and apps that have obtained permission to access user location through Location Services. 

Test your app on the latest iOS 13 beta to make sure it works properly. If your app requires valid Wi-Fi SSID and BSSID information to function, you can do the following:
For accessory setup apps, use the NEHotSpotConfiguration API, which now has the option to pass a prefix of the SSID hotspot your app expects to connect to.
For other types of apps, use the CoreLocation API to request the user’s consent to access location information.

Learn more by reading the updated documentation or viewing the the Advances in Networking session video from WWDC19. You can also submit a TSI for code-level support. 

Best regards,
Apple Developer Relations

解决方案---获取位置权限

- (NSString*) getWifiSsid {
    if (@available(iOS 13.0, *)) {
        //用户明确拒绝，可以弹窗提示用户到设置中手动打开权限
        if ([CLLocationManager authorizationStatus] == kCLAuthorizationStatusDenied) {
            NSLog(@"User has explicitly denied authorization for this application, or location services are disabled in Settings.");
            //使用下面接口可以打开当前应用的设置页面
            //[[UIApplication sharedApplication] openURL:[NSURL URLWithString:UIApplicationOpenSettingsURLString]];
            return nil;
        }
        CLLocationManager* cllocation = [[CLLocationManager alloc] init];
        if(![CLLocationManager locationServicesEnabled] || [CLLocationManager authorizationStatus] == kCLAuthorizationStatusNotDetermined){
            //弹框提示用户是否开启位置权限
            [cllocation requestWhenInUseAuthorization];
            usleep(500);
            //递归等待用户选选择
            return [self getWifiSsid];
        }
    }
    NSString *wifiName = nil;
    CFArrayRef wifiInterfaces = CNCopySupportedInterfaces();
    if (!wifiInterfaces) {
        return nil;
    }
    NSArray *interfaces = (__bridge NSArray *)wifiInterfaces;
    for (NSString *interfaceName in interfaces) {
        CFDictionaryRef dictRef = CNCopyCurrentNetworkInfo((__bridge CFStringRef)(interfaceName));
        
        if (dictRef) {
            NSDictionary *networkInfo = (__bridge NSDictionary *)dictRef;
            NSLog(@"network info -> %@", networkInfo);
            wifiName = [networkInfo objectForKey:(__bridge NSString *)kCNNetworkInfoKeySSID];
            CFRelease(dictRef);
        }
    }
    
    CFRelease(wifiInterfaces);
    return wifiName;
}

获取结果

• 同意的打印结果

2019/08/09 14:23:47:121 network info -> {
    BSSID = "4c:ed:fb:a0:91:e4";
    SSID = "Asus_c039";
    SSIDDATA = <41737573 5f633033 39>;
}

• 如果用户不获取位置权限的结果

2019/08/09 14:34:01:586 network info -> {
    BSSID = "00:00:00:00:00:00";
    SSID = WLAN;
    SSIDDATA = <574c414e>;
}

• 如果项目本身已经打开位置权限，则可以直接获取。

解决方案---使用 NEHotspotConfiguration

邮件中还提到可以通过NEHotspotConfiguration获取，之前没有理解是什么意思。 后面发现 如果APP使用NEHotspotConfiguration 接口连接的WiFi还是可以继续通过 CNCopyCurrentNetworkInfo SSID 和BSSID。

//连接WiFi
NEHotspotConfiguration *c = [[NEHotspotConfiguration alloc] initWithSSID:@"Asus_c039" passphrase:@"leedarson@638" isWEP:NO];
NEHotspotConfigurationManager *m = [NEHotspotConfigurationManager sharedManager];
[m applyConfiguration:c completionHandler:^(NSError * _Nullable error) {
    NSLog(@"error :%@",error);
}];

//获取ssid 
- (NSString*) getWifiSsid {
    NSString *wifiName = nil;
    
    CFArrayRef wifiInterfaces = CNCopySupportedInterfaces();
    
    if (!wifiInterfaces) {
        return nil;
    }
    
    NSArray *interfaces = (__bridge NSArray *)wifiInterfaces;
    
    for (NSString *interfaceName in interfaces) {
        CFDictionaryRef dictRef = CNCopyCurrentNetworkInfo((__bridge CFStringRef)(interfaceName));
        
        if (dictRef) {
            NSDictionary *networkInfo = (__bridge NSDictionary *)dictRef;
            NSLog(@"network info -> %@", networkInfo);
            wifiName = [networkInfo objectForKey:(__bridge NSString *)kCNNetworkInfoKeySSID];
            
            CFRelease(dictRef);
        }
    }
    
    CFRelease(wifiInterfaces);
    return wifiName;
}

8.21 更新NEHotspotConfiguration 相关