iOS 判断当前网络状态(WiFi/2G/3G/4G)

方法一、第三方框架AFNetworkReachabilityManager

  如常用的AFNetworking中有一个AFNetworkReachabilityManager的类，可以检测当前的网络状态。
  在AFNetworkReachabilityManager头文件中我们可以看到网络状态的枚举值，如下：

typedef NS_ENUM(NSInteger, AFNetworkReachabilityStatus) {
    AFNetworkReachabilityStatusUnknown          = -1, //位置网络
    AFNetworkReachabilityStatusNotReachable     = 0, // 无网络
    AFNetworkReachabilityStatusReachableViaWWAN = 1, //流量
    AFNetworkReachabilityStatusReachableViaWiFi = 2, // WiFi
};

（1）获取网络状态：

#import "AFNetworkReachabilityManager.h"

+ (void)getNetworkStates {
    // 监控网络状态
    AFNetworkReachabilityManager *reachability = [AFNetworkReachabilityManager sharedManager];
    [reachability setReachabilityStatusChangeBlock:^(AFNetworkReachabilityStatus status) {
        switch (status) {
            case AFNetworkReachabilityStatusUnknown:
                NSLog(@"状态不知道");
                break;
            case AFNetworkReachabilityStatusNotReachable:
                NSLog(@"没网络");
                break;
            case AFNetworkReachabilityStatusReachableViaWiFi:
                NSLog(@"WIFI");
                break;
            case AFNetworkReachabilityStatusReachableViaWWAN:
                NSLog(@"流量");
                break;
            default:
                break;
        }
    }];
    //开始监控
    [reachability startMonitoring];
}

（2）当用户为手机流量时，判断具体网络类型

  这时可以使用系统自带的API来判断是2G、3G还是4G，这就用到了CTTelephonyNetworkInfo这类，记得在工程添加CoreTelephony.framework框架，并导入头文件#import <CoreTelephony/CTTelephonyNetworkInfo.h>

#import <CoreTelephony/CTTelephonyNetworkInfo.h>

- (NSString *)getNetType{
    CTTelephonyNetworkInfo *info = [CTTelephonyNetworkInfo new];
    NSString *networkType = @"";
    if ([info respondsToSelector:@selector(currentRadioAccessTechnology)]) {
        NSString *currentStatus = info.currentRadioAccessTechnology;
        NSArray *network2G = @[CTRadioAccessTechnologyGPRS, CTRadioAccessTechnologyEdge, CTRadioAccessTechnologyCDMA1x];
        NSArray *network3G = @[CTRadioAccessTechnologyWCDMA, CTRadioAccessTechnologyHSDPA, CTRadioAccessTechnologyHSUPA, CTRadioAccessTechnologyCDMAEVDORev0, CTRadioAccessTechnologyCDMAEVDORevA, CTRadioAccessTechnologyCDMAEVDORevB, CTRadioAccessTechnologyeHRPD];
        NSArray *network4G = @[CTRadioAccessTechnologyLTE];
        
        if ([network2G containsObject:currentStatus]) {
            networkType = @"2G";
        }else if ([network3G containsObject:currentStatus]) {
            networkType = @"3G";
        }else if ([network4G containsObject:currentStatus]){
            networkType = @"4G";
        }else {
            networkType = @"未知网络";
        }
    }
    return networkType;
}

  在网络为流量时，还可以通过另一个方法CTRadioAccessTechnologyDidChangeNotification来通过通知NSNotificationCenter来获取蜂窝网络切换状态。这里面CTTelephonyNetworkInfo初始化要使用全局实例变量，因为局部变量在某个地方被release了，这个错误和定位功能使用局部变量定义CLLocationManager如出一辙，通知代理方法不执行。这种错误容易出现在ARC环境下。因为ARC是Xcode根据情况隐式添加release方法，block语句和代理方法都不是立即执行的,等到执行的时候，networkInfo对象可能已经被release了。Xcode编译时，看到后面没有用到networkInfo对象,以为不需要了，所以就把它release掉了，MRC应该不会出现类似情况。
如果使用通知的这个方法就必须要用实例变量了，所以用self.networkInfo.currentRadioAccessTechnology是可以收到通知的

//定义全局实例变量
@property (nonatomic, strong) CTTelephonyNetworkInfo *networkInfo;

- (void)viewDidLoad {
    [super viewDidLoad];

    self.networkInfo = [[CTTelephonyNetworkInfo alloc] init];
    NSLog(@"Initial connection: %@", self.networkInfo.currentRadioAccessTechnology);
    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(radioAccessChanged) name:
     CTRadioAccessTechnologyDidChangeNotification object:nil];
}

- (void)radioAccessChanged {
    NSLog(@"Now you're connected via %@", self.networkInfo.currentRadioAccessTechnology);
}

方法二、通过系统statusBar判断，此方法用到了私有API（不建议使用）

//获取statusBar的网络状态
//支持iPhone X
- (NSString *)getNetWorkStates{
    NSArray *children;
    UIApplication *app = [UIApplication sharedApplication];
    NSString *state = @"无网络";
    //iPhone X
    if ([[app valueForKeyPath:@"_statusBar"] isKindOfClass:NSClassFromString(@"UIStatusBar_Modern")]) {
        children = [[[[app valueForKeyPath:@"_statusBar"] valueForKeyPath:@"_statusBar"] valueForKeyPath:@"foregroundView"] subviews];
        for (UIView *view in children) {
            for (id child in view.subviews) {
                //wifi
                if ([child isKindOfClass:NSClassFromString(@"_UIStatusBarWifiSignalView")]) {
                    state = @"wifi";
                }
                //2G 3G 4G
                if ([child isKindOfClass:NSClassFromString(@"_UIStatusBarStringView")]) {
                    if ([[child valueForKey:@"_originalText"] containsString:@"G"]) {
                        state = [child valueForKey:@"_originalText"];
                    }
                }
            }
        }
    }else {
        children = [[[app valueForKeyPath:@"_statusBar"] valueForKeyPath:@"foregroundView"] subviews];
        for (id child in children) {
            if ([child isKindOfClass:NSClassFromString(@"UIStatusBarDataNetworkItemView")]) {
                //获取到状态栏
                switch ([[child valueForKeyPath:@"dataNetworkType"] intValue]) {
                    case 0:
                        state = @"无网络";
                        //无网模式
                        break;
                    case 1:
                        state = @"2G";
                        break;
                    case 2:
                        state = @"3G";
                        break;
                    case 3:
                        state = @"4G";
                        break;
                    case 5:
                        state = @"wifi";
                        break;
                    default:
                        break;
                }
            }
        }
    }
    return state;
}

三、获取运营商信息

#import <CoreTelephony/CTTelephonyNetworkInfo.h>
#import <CoreTelephony/CTCarrier.h>

- (NSString *)getMobileProvider{
    CTTelephonyNetworkInfo *info = [[CTTelephonyNetworkInfo alloc] init];
    CTCarrier *carrier = info.subscriberCellularProvider;
    //运营商，如中国移动，中国联通，中国电信
    NSString *carrierName = [carrier carrierName];
    return carrierName ?: @"";
}