https://www.jianshu.com/p/0135e7db5a69

iOS如何在应用中连接WIFI

1、打开Hotspot Configuration权限。
2、在info.plist中添加"Required background modes"，在item0赋值为"network-authentication"。注意，当添加完成后，App会打开"Background Modes"能力。
3、导入头文件"#import <NetworkExtension/NetworkExtension.h>"。
4、通过代码连接指定SSID的WIFI。

NEHotspotConfiguration* config = [[NEHotspotConfiguration alloc] initWithSSID:@"WIFI SSID" passphrase:@"WIFI 密码" isWEP:NO];
    
    NEHotspotConfigurationManager* manager = [NEHotspotConfigurationManager sharedManager];
    [manager applyConfiguration:config completionHandler:^(NSError * _Nullable error) {
        NSLog(@"%@",error);
    }];

如何在应用中获取已经连接的WIFI SSID

1、iOS14以上版本，获取当前系统已经连接的WiFi SSID可通过以下方法

NEHotspotConfigurationManager* manager = [NEHotspotConfigurationManager sharedManager];
[NEHotspotNetwork fetchCurrentWithCompletionHandler:^(NEHotspotNetwork * _Nullable currentNetwork) {
    NSLog(@"current :%@", currentNetwork.SSID);
    //打印结果：current :UKeeper-5G
}];

iOS14以下，可以使用以下方式获取当前连接的WiFi SSID

+ (NSString*)wifSsid{
    NSArray *interfaces = (__bridge_transfer NSArray*)CNCopySupportedInterfaces();
    NSDictionary *info = nil;
    for (NSString *ifname in interfaces) {
        info = (__bridge_transfer NSDictionary*)CNCopyCurrentNetworkInfo((__bridge CFStringRef)ifname);
        if (info && [info count]) {
            break;
        }
        info = nil;
    }
    
    NSString *ssid = nil;
    
    if ( info ){
        ssid = [info objectForKey:@"SSID"];
    }
    info = nil;
    return ssid? ssid:@"";
}

2、由于iOS12对获取WiFi做了限制，App需要打开”Access WiFi Infomation“权限后才能获取已经连接的WiFi SSID。注意：该权限只有付费帐号才能打开。
3、iOS13系统对WiFi SSID获取又进行了限制，需要开启定位服务后才能获取已经连接的WiFi SSID。打开定位权限如下：

<key>NSLocationAlwaysUsageDescription</key>
<string></string>
<key>NSLocationAlwaysAndWhenInUseUsageDescription</key>
<string></string>
<key>NSLocationUsageDescription</key>
<string></string>
<key>NSLocationWhenInUseUsageDescription</key>
<string></string>

4、iOS14系统及以上，需要开启精准定位服务后才能获取已经连接的WiFi SSID。获取精准定位的方法如下：

self.manager = [[CLLocationManager alloc] init];
BOOL isFullAccuracy = (self.manager.accuracyAuthorization == CLAccuracyAuthorizationFullAccuracy);
if(!isFullAccuracy){
    [self.manager requestTemporaryFullAccuracyAuthorizationWithPurposeKey:@"WantsToGetWiFiSSID"];
}