AFNetworkingReachabilityManager.h

#import <Foundation/Foundation.h>

#if !TARGET_OS_WATCH
#import <SystemConfiguration/SystemConfiguration.h>

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

NS_ASSUME_NONNULL_BEGIN


@interface AFNetworkReachabilityManager : NSObject

/**
 当前网络连接状态.
 */
@property (readonly, nonatomic, assign) AFNetworkReachabilityStatus networkReachabilityStatus;

/**
 当前网络是否可用
 */
@property (readonly, nonatomic, assign, getter = isReachable) BOOL reachable;

/**
当前网络是否可以通过WWAN进行连接.
 */
@property (readonly, nonatomic, assign, getter = isReachableViaWWAN) BOOL reachableViaWWAN;

/**
 当前网络是否可以通过 WiFi进行连接.
 */
@property (readonly, nonatomic, assign, getter = isReachableViaWiFi) BOOL reachableViaWiFi;

/**
 返回一个单例的manager对象.
 */
+ (instancetype)sharedManager;

/**
 创建并返回一个默认socket地址的manager对象
 */
+ (instancetype)manager;

/**
 为指定的域名返回一个manager对象
 */
+ (instancetype)managerForDomain:(NSString *)domain;

/**
 为制定的Socket地址返回一个manager对象
 */
+ (instancetype)managerForAddress:(const void *)address;

/**
 为特定的reachability对象返回一个manager对象
 */
- (instancetype)initWithReachability:(SCNetworkReachabilityRef)reachability NS_DESIGNATED_INITIALIZER;

/**
开始监听网络连接状态
 */
- (void)startMonitoring;

/**
停止监听网络连接状态
 */
- (void)stopMonitoring;

/**
返回一个本地化的网络状态字符串
 */
- (NSString *)localizedNetworkReachabilityStatusString;

/**
 当网络状态发生变化的时候调用此方法,设置回调函数进行调用.
 */
- (void)setReachabilityStatusChangeBlock:(nullable void (^)(AFNetworkReachabilityStatus status))block;

@end

FOUNDATION_EXPORT NSString * const AFNetworkingReachabilityDidChangeNotification;
FOUNDATION_EXPORT NSString * const AFNetworkingReachabilityNotificationStatusItem;
FOUNDATION_EXPORT NSString * AFStringFromNetworkReachabilityStatus(AFNetworkReachabilityStatus status);

NS_ASSUME_NONNULL_END
#endif

AFNetworkingReachabilityManager.m

#import "AFNetworkReachabilityManager.h"
#if !TARGET_OS_WATCH

#import <netinet/in.h>
#import <netinet6/in6.h>
#import <arpa/inet.h>
#import <ifaddrs.h>
#import <netdb.h>

NSString * const AFNetworkingReachabilityDidChangeNotification = @"com.alamofire.networking.reachability.change";
NSString * const AFNetworkingReachabilityNotificationStatusItem = @"AFNetworkingReachabilityNotificationStatusItem";

typedef void (^AFNetworkReachabilityStatusBlock)(AFNetworkReachabilityStatus status);

NSString * AFStringFromNetworkReachabilityStatus(AFNetworkReachabilityStatus status) {
    switch (status) {
        case AFNetworkReachabilityStatusNotReachable:
            return NSLocalizedStringFromTable(@"Not Reachable", @"AFNetworking", nil);
        case AFNetworkReachabilityStatusReachableViaWWAN:
            return NSLocalizedStringFromTable(@"Reachable via WWAN", @"AFNetworking", nil);
        case AFNetworkReachabilityStatusReachableViaWiFi:
            return NSLocalizedStringFromTable(@"Reachable via WiFi", @"AFNetworking", nil);
        case AFNetworkReachabilityStatusUnknown:
        default:
            return NSLocalizedStringFromTable(@"Unknown", @"AFNetworking", nil);
    }
}

static AFNetworkReachabilityStatus AFNetworkReachabilityStatusForFlags(SCNetworkReachabilityFlags flags) {
    BOOL isReachable = ((flags & kSCNetworkReachabilityFlagsReachable) != 0);
    BOOL needsConnection = ((flags & kSCNetworkReachabilityFlagsConnectionRequired) != 0);
    BOOL canConnectionAutomatically = (((flags & kSCNetworkReachabilityFlagsConnectionOnDemand ) != 0) || ((flags & kSCNetworkReachabilityFlagsConnectionOnTraffic) != 0));
    BOOL canConnectWithoutUserInteraction = (canConnectionAutomatically && (flags & kSCNetworkReachabilityFlagsInterventionRequired) == 0);
    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;
}

/**
 * 为主线程创建一个状态改变的通知的队列
 * 用来保证接收到的通知在按顺序排列
 * 如果通知直接发出,而不再队列中可能会导致多线程错误.
 */
static void AFPostReachabilityStatusChange(SCNetworkReachabilityFlags flags, AFNetworkReachabilityStatusBlock block) {
    AFNetworkReachabilityStatus status = AFNetworkReachabilityStatusForFlags(flags);
    dispatch_async(dispatch_get_main_queue(), ^{
        if (block) {
            block(status);
        }
        NSNotificationCenter *notificationCenter = [NSNotificationCenter defaultCenter];
        NSDictionary *userInfo = @{ AFNetworkingReachabilityNotificationStatusItem: @(status) };
        [notificationCenter postNotificationName:AFNetworkingReachabilityDidChangeNotification object:nil userInfo:userInfo];
    });
}

static void AFNetworkReachabilityCallback(SCNetworkReachabilityRef __unused target, SCNetworkReachabilityFlags flags, void *info) {
    AFPostReachabilityStatusChange(flags, (__bridge AFNetworkReachabilityStatusBlock)info);
}


static const void * AFNetworkReachabilityRetainCallback(const void *info) {
    return Block_copy(info);
}

static void AFNetworkReachabilityReleaseCallback(const void *info) {
    if (info) {
        Block_release(info);
    }
}

@interface AFNetworkReachabilityManager ()
@property (readonly, nonatomic, assign) SCNetworkReachabilityRef networkReachability;
@property (readwrite, nonatomic, assign) AFNetworkReachabilityStatus networkReachabilityStatus;
@property (readwrite, nonatomic, copy) AFNetworkReachabilityStatusBlock networkReachabilityStatusBlock;
@end

@implementation AFNetworkReachabilityManager

+ (instancetype)sharedManager {
    static AFNetworkReachabilityManager *_sharedManager = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        _sharedManager = [self manager];
    });

    return _sharedManager;
}

+ (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)manager
{
#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];
}

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

    _networkReachability = CFRetain(reachability);
    self.networkReachabilityStatus = AFNetworkReachabilityStatusUnknown;

    return self;
}

- (instancetype)init NS_UNAVAILABLE
{
    return nil;
}

- (void)dealloc {
    [self stopMonitoring];
    
    if (_networkReachability != NULL) {
        CFRelease(_networkReachability);
    }
}

#pragma mark -

- (BOOL)isReachable {
    return [self isReachableViaWWAN] || [self isReachableViaWiFi];
}

- (BOOL)isReachableViaWWAN {
    return self.networkReachabilityStatus == AFNetworkReachabilityStatusReachableViaWWAN;
}

- (BOOL)isReachableViaWiFi {
    return self.networkReachabilityStatus == AFNetworkReachabilityStatusReachableViaWiFi;
}

#pragma mark -

- (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);
        }

    };

    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);
        }
    });
}

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

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

#pragma mark -

- (NSString *)localizedNetworkReachabilityStatusString {
    return AFStringFromNetworkReachabilityStatus(self.networkReachabilityStatus);
}

#pragma mark -

- (void)setReachabilityStatusChangeBlock:(void (^)(AFNetworkReachabilityStatus status))block {
    self.networkReachabilityStatusBlock = block;
}

#pragma mark - NSKeyValueObserving

+ (NSSet *)keyPathsForValuesAffectingValueForKey:(NSString *)key {
    if ([key isEqualToString:@"reachable"] || [key isEqualToString:@"reachableViaWWAN"] || [key isEqualToString:@"reachableViaWiFi"]) {
        return [NSSet setWithObject:@"networkReachabilityStatus"];
    }

    return [super keyPathsForValuesAffectingValueForKey:key];
}

@end
#endif