AFNetworking3.0网络状态监测<二>

SystemConfiguration网络监测

网络状态监测使用SystemConfiguration这个API 从包含的头文件中可以看到，之前的网络库ASIHttpRequest中的网络状态监测类Reachability也是对SystemConfiguration的一层封装，AFNetworkReachabilityStatus 代表获取到的网络状态

的

typedef NS_ENUM(NSInteger, AFNetworkReachabilityStatus) {
    AFNetworkReachabilityStatusUnknown          = -1,    // 位置
    AFNetworkReachabilityStatusNotReachable     = 0,    //无网络   不能连接
    AFNetworkReachabilityStatusReachableViaWWAN = 1,  // 蜂窝网
    AFNetworkReachabilityStatusReachableViaWiFi = 2,     //WIFI
};

以下两个宏代表在他们中间的参数默认是nonnull类型的，相当于程序猿做的标记，用于交流这几个参数不能为空

NS_ASSUME_NONNULL_BEGIN
NS_ASSUME_NONNULL_END 

这张图可以反映出本篇的大致实现过程

Paste_Image.png

初始化manager

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一共五种方式 其实从etworkReachabilityRef的创建方式来看可以说是两种

+ (instancetype)managerForDomain:(NSString *)domain {
    SCNetworkReachabilityRef reachability = SCNetworkReachabilityCreateWithName(kCFAllocatorDefault, [domain UTF8String]);

    AFNetworkReachabilityManager *manager = [[self alloc] initWithReachability:reachability];
    
    CFRelease(reachability);

    return manager;
}

+ (instancetype)managerForAddress:(const void *)address {
    SCNetworkReachabilityRef reachability = SCNetworkReachabilityCreateWithAddress(kCFAllocatorDefault, (const struct sockaddr *)address);
    AFNetworkReachabilityManager *manager = [[self alloc] initWithReachability:reachability];

    CFRelease(reachability);
    
    return manager;
}

block方式获取状态

FOUNDATION_EXPORT NSString * const AFNetworkingReachabilityDidChangeNotification;
FOUNDATION_EXPORT NSString * const AFNetworkingReachabilityNotificationStatusItem;

通知方式

/**
 Sets a callback to be executed when the network availability of the `baseURL` host changes.

 @param block A block object to be executed when the network availability of the `baseURL` host changes.. This block has no return value and takes a single argument which represents the various reachability states from the device to the `baseURL`.
 // 设置网络状态回调
 */
- (void)setReachabilityStatusChangeBlock:(nullable void (^)(AFNetworkReachabilityStatus status))block;

开始监听

- (void)startMonitoring {
    [self stopMonitoring];

    if (!self.networkReachability) {
        return;
    }

    __weak __typeof(self)weakSelf = self;
    AFNetworkReachabilityStatusBlock callback = ^(AFNetworkReachabilityStatus status) {
        __strong __typeof(weakSelf)strongSelf = weakSelf;

        strongSelf.networkReachabilityStatus = status;
        if (strongSelf.networkReachabilityStatusBlock) {
            strongSelf.networkReachabilityStatusBlock(status);
        }

    };
     // 创建上下文  SCNetworkReachabilityContext 结构体
    SCNetworkReachabilityContext context = {0, (__bridge void *)callback, AFNetworkReachabilityRetainCallback, AFNetworkReachabilityReleaseCallback, NULL};
 //  设置回调
    SCNetworkReachabilitySetCallback(self.networkReachability, AFNetworkReachabilityCallback, &context);
 //  加入RunLoop
    SCNetworkReachabilityScheduleWithRunLoop(self.networkReachability, CFRunLoopGetMain(), kCFRunLoopCommonModes);
    //  异步发送网络状态
    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0),^{
        SCNetworkReachabilityFlags flags;
        if (SCNetworkReachabilityGetFlags(self.networkReachability, &flags)) {
            AFPostReachabilityStatusChange(flags, callback);
        }
    });
}

SCNetworkReachabilityFlags 转为 AFNetworkReachabilityStatus

通过开发监听那个方法可以获取到系统返回的SCNetworkReachabilityFlags值
接下来看下如何进行转换 这是一个同步的方法

static AFNetworkReachabilityStatus AFNetworkReachabilityStatusForFlags(SCNetworkReachabilityFlags flags) {
 // 是否能够连接
    BOOL isReachable = ((flags & kSCNetworkReachabilityFlagsReachable) != 0);
 // 在联网之前需要建立连接
    BOOL needsConnection = ((flags & kSCNetworkReachabilityFlagsConnectionRequired) != 0);
  // 是否可以自动连接
    BOOL canConnectionAutomatically = (((flags & kSCNetworkReachabilityFlagsConnectionOnDemand ) != 0) || ((flags & kSCNetworkReachabilityFlagsConnectionOnTraffic) != 0));
 // 是否可以连接，在不需要用户手动设置的前提下
    BOOL canConnectWithoutUserInteraction = (canConnectionAutomatically && (flags & kSCNetworkReachabilityFlagsInterventionRequired) == 0);
 // 是否可以联网的条件 1.能够连接 2.不需要建立连接或者不需要用户手动设置连接 就表示能够连接到网络
    BOOL isNetworkReachable = (isReachable && (!needsConnection || canConnectWithoutUserInteraction));

    AFNetworkReachabilityStatus status = AFNetworkReachabilityStatusUnknown;
    if (isNetworkReachable == NO) {
        status = AFNetworkReachabilityStatusNotReachable;
    }
#if TARGET_OS_IPHONE
    else if ((flags & kSCNetworkReachabilityFlagsIsWWAN) != 0) {
        status = AFNetworkReachabilityStatusReachableViaWWAN;
    }
#endif
    else {
        status = AFNetworkReachabilityStatusReachableViaWiFi;
    }

    return status;
}

取消监听

- (void)stopMonitoring {
    if (!self.networkReachability) {
        return;
    }
    //  停止监控
    SCNetworkReachabilityUnscheduleFromRunLoop(self.networkReachability, CFRunLoopGetMain(), kCFRunLoopCommonModes);
}