AFNetworkReachabilityManager

這個(gè)類主要是監(jiān)聽當(dāng)前的網(wǎng)絡(luò)狀態(tài)，并通過(guò)通知廣播給調(diào)用者。

網(wǎng)絡(luò)狀態(tài)有如下幾種，分別對(duì)應(yīng)的未知、斷網(wǎng)、移動(dòng)網(wǎng)絡(luò)、Wi-Fi

typedef NS_ENUM(NSInteger, AFNetworkReachabilityStatus) {
    AFNetworkReachabilityStatusUnknown          = -1,
    AFNetworkReachabilityStatusNotReachable     = 0,
    AFNetworkReachabilityStatusReachableViaWWAN = 1,
    AFNetworkReachabilityStatusReachableViaWiFi = 2,
};

官方已經(jīng)提供一個(gè)句柄來(lái)標(biāo)識(shí)網(wǎng)絡(luò)地址狀態(tài)，就是它”SCNetworkReachabilityRef”，先看看AFNetworkReachabilityManager其中幾個(gè)初始化方法。

• 第一個(gè)方法使用domain參數(shù)來(lái)初始化一個(gè)實(shí)例，同理第二個(gè)方法使用address來(lái)初始化實(shí)例。這里需要注意，如果使用非Cocoa框架的類創(chuàng)建一個(gè)實(shí)例，需要手動(dòng)對(duì)這個(gè)對(duì)象進(jìn)行內(nèi)存管理。
• 第四個(gè)方法是作者推薦用的初始化方法，根據(jù)當(dāng)前iOS開發(fā)最低支持編譯版本是否大于9.0來(lái)創(chuàng)建對(duì)應(yīng)的網(wǎng)絡(luò)協(xié)議對(duì)象，大于9.0則創(chuàng)建IPv6，否則創(chuàng)建IPv4

+ (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;
}

- (instancetype)initWithReachability:(SCNetworkReachabilityRef)reachability {
    self = [super init];
    if (!self) {
        return nil;
    }
    _networkReachability = CFRetain(reachability);
    self.networkReachabilityStatus = AFNetworkReachabilityStatusUnknown;
    return self;
}

+ (instancetype)manager {
// __IPHONE_OS_VERSION_MIN_REQUIRED 表示當(dāng)前開發(fā)環(huán)境最低支持的版本號(hào)
// 編譯時(shí)判斷如果當(dāng)前iOS開發(fā)環(huán)境版本低于9.0則使用IPv4,否則使用IPv6的結(jié)構(gòu)體

#if (defined(__IPHONE_OS_VERSION_MIN_REQUIRED) && __IPHONE_OS_VERSION_MIN_REQUIRED >= 90000) || (defined(__MAC_OS_X_VERSION_MIN_REQUIRED) && __MAC_OS_X_VERSION_MIN_REQUIRED >= 101100)
    struct sockaddr_in6 address;
    bzero(&address, sizeof(address));
    address.sin6_len = sizeof(address);
    address.sin6_family = AF_INET6;
#else
    struct sockaddr_in address;
    bzero(&address, sizeof(address));
    address.sin_len = sizeof(address);
    address.sin_family = AF_INET;
#endif
    return [self managerForAddress:&address];
}

• 開啟監(jiān)聽

- (void)startMonitoring {
    [self stopMonitoring];

    if (!self.networkReachability) {
        return;
    }

     // 設(shè)置網(wǎng)絡(luò)狀態(tài)監(jiān)聽回調(diào)
    __weak __typeof(self)weakSelf = self;
    AFNetworkReachabilityStatusBlock callback = ^(AFNetworkReachabilityStatus status) {
        __strong __typeof(weakSelf)strongSelf = weakSelf;
        strongSelf.networkReachabilityStatus = status;
        if (strongSelf.networkReachabilityStatusBlock) {
            strongSelf.networkReachabilityStatusBlock(status);
        }
    };

    SCNetworkReachabilityContext context = {0, (__bridge void *)callback, AFNetworkReachabilityRetainCallback, AFNetworkReachabilityReleaseCallback, NULL};
    SCNetworkReachabilitySetCallback(self.networkReachability, AFNetworkReachabilityCallback, &context);
    SCNetworkReachabilityScheduleWithRunLoop(self.networkReachability, CFRunLoopGetMain(), kCFRunLoopCommonModes);

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0),^{
        SCNetworkReachabilityFlags flags;
        if (SCNetworkReachabilityGetFlags(self.networkReachability, &flags)) {
            AFPostReachabilityStatusChange(flags, callback);
        }
    });
}

• 關(guān)閉監(jiān)聽

- (void)stopMonitoring {
    if (!self.networkReachability) {
        return;
    }

    SCNetworkReachabilityUnscheduleFromRunLoop(self.networkReachability, CFRunLoopGetMain(), kCFRunLoopCommonModes);
}