Delete more unused code from Reachability.
This commit is contained in:
Brent Simmons
parent
3b59ffc446
commit
7311c25d35
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@ -29,10 +29,7 @@ import SystemConfiguration
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import Foundation
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public enum ReachabilityError: Error {
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case failedToCreateWithAddress(sockaddr, Int32)
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case failedToCreateWithHostname(String, Int32)
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case unableToSetCallback(Int32)
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case unableToSetDispatchQueue(Int32)
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case failedToCreateWithHostname(String, Int32)
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case unableToGetFlags(Int32)
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}
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@ -96,132 +93,31 @@ public class Reachability {
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}
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}
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fileprivate(set) var notifierRunning = false
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fileprivate let reachabilityRef: SCNetworkReachability
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fileprivate let reachabilitySerialQueue: DispatchQueue
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fileprivate let notificationQueue: DispatchQueue?
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fileprivate(set) var flags: SCNetworkReachabilityFlags?
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fileprivate(set) var notifierRunning = false
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fileprivate let reachabilityRef: SCNetworkReachability
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fileprivate let reachabilitySerialQueue: DispatchQueue
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fileprivate(set) var flags: SCNetworkReachabilityFlags?
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required public init(reachabilityRef: SCNetworkReachability,
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queueQoS: DispatchQoS = .default,
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targetQueue: DispatchQueue? = nil,
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notificationQueue: DispatchQueue? = .main) {
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self.allowsCellularConnection = true
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self.reachabilityRef = reachabilityRef
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self.reachabilitySerialQueue = DispatchQueue(label: "uk.co.ashleymills.reachability", qos: queueQoS, target: targetQueue)
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self.notificationQueue = notificationQueue
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}
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required public init(reachabilityRef: SCNetworkReachability,
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queueQoS: DispatchQoS = .default,
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targetQueue: DispatchQueue? = nil) {
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self.allowsCellularConnection = true
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self.reachabilityRef = reachabilityRef
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self.reachabilitySerialQueue = DispatchQueue(label: "uk.co.ashleymills.reachability", qos: queueQoS, target: targetQueue)
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}
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public convenience init(hostname: String,
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queueQoS: DispatchQoS = .default,
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targetQueue: DispatchQueue? = nil,
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notificationQueue: DispatchQueue? = .main) throws {
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guard let ref = SCNetworkReachabilityCreateWithName(nil, hostname) else {
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throw ReachabilityError.failedToCreateWithHostname(hostname, SCError())
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}
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self.init(reachabilityRef: ref, queueQoS: queueQoS, targetQueue: targetQueue, notificationQueue: notificationQueue)
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}
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public convenience init(queueQoS: DispatchQoS = .default,
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targetQueue: DispatchQueue? = nil,
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notificationQueue: DispatchQueue? = .main) throws {
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var zeroAddress = sockaddr()
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zeroAddress.sa_len = UInt8(MemoryLayout<sockaddr>.size)
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zeroAddress.sa_family = sa_family_t(AF_INET)
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guard let ref = SCNetworkReachabilityCreateWithAddress(nil, &zeroAddress) else {
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throw ReachabilityError.failedToCreateWithAddress(zeroAddress, SCError())
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}
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self.init(reachabilityRef: ref, queueQoS: queueQoS, targetQueue: targetQueue, notificationQueue: notificationQueue)
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}
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deinit {
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stopNotifier()
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}
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public convenience init(hostname: String,
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queueQoS: DispatchQoS = .default,
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targetQueue: DispatchQueue? = nil) throws {
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guard let ref = SCNetworkReachabilityCreateWithName(nil, hostname) else {
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throw ReachabilityError.failedToCreateWithHostname(hostname, SCError())
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}
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self.init(reachabilityRef: ref, queueQoS: queueQoS, targetQueue: targetQueue)
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}
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}
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public extension Reachability {
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// MARK: - *** Notifier methods ***
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func startNotifier() throws {
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guard !notifierRunning else { return }
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let callback: SCNetworkReachabilityCallBack = { (reachability, flags, info) in
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guard let info = info else { return }
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// `weakifiedReachability` is guaranteed to exist by virtue of our
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// retain/release callbacks which we provided to the `SCNetworkReachabilityContext`.
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let weakifiedReachability = Unmanaged<ReachabilityWeakifier>.fromOpaque(info).takeUnretainedValue()
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// The weak `reachability` _may_ no longer exist if the `Reachability`
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// object has since been deallocated but a callback was already in flight.
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weakifiedReachability.reachability?.flags = flags
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}
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let weakifiedReachability = ReachabilityWeakifier(reachability: self)
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let opaqueWeakifiedReachability = Unmanaged<ReachabilityWeakifier>.passUnretained(weakifiedReachability).toOpaque()
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var context = SCNetworkReachabilityContext(
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version: 0,
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info: UnsafeMutableRawPointer(opaqueWeakifiedReachability),
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retain: { (info: UnsafeRawPointer) -> UnsafeRawPointer in
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let unmanagedWeakifiedReachability = Unmanaged<ReachabilityWeakifier>.fromOpaque(info)
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_ = unmanagedWeakifiedReachability.retain()
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return UnsafeRawPointer(unmanagedWeakifiedReachability.toOpaque())
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},
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release: { (info: UnsafeRawPointer) -> Void in
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let unmanagedWeakifiedReachability = Unmanaged<ReachabilityWeakifier>.fromOpaque(info)
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unmanagedWeakifiedReachability.release()
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},
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copyDescription: { (info: UnsafeRawPointer) -> Unmanaged<CFString> in
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let unmanagedWeakifiedReachability = Unmanaged<ReachabilityWeakifier>.fromOpaque(info)
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let weakifiedReachability = unmanagedWeakifiedReachability.takeUnretainedValue()
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let description = weakifiedReachability.reachability?.description ?? "nil"
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return Unmanaged.passRetained(description as CFString)
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}
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)
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if !SCNetworkReachabilitySetCallback(reachabilityRef, callback, &context) {
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stopNotifier()
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throw ReachabilityError.unableToSetCallback(SCError())
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}
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if !SCNetworkReachabilitySetDispatchQueue(reachabilityRef, reachabilitySerialQueue) {
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stopNotifier()
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throw ReachabilityError.unableToSetDispatchQueue(SCError())
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}
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// Perform an initial check
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try setReachabilityFlags()
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notifierRunning = true
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}
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func stopNotifier() {
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defer { notifierRunning = false }
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SCNetworkReachabilitySetCallback(reachabilityRef, nil, nil)
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SCNetworkReachabilitySetDispatchQueue(reachabilityRef, nil)
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}
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// MARK: - *** Connection test methods ***
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@available(*, deprecated, message: "Please use `connection != .none`")
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var isReachable: Bool {
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return connection != .unavailable
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}
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@available(*, deprecated, message: "Please use `connection == .cellular`")
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var isReachableViaWWAN: Bool {
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// Check we're not on the simulator, we're REACHABLE and check we're on WWAN
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return connection == .cellular
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}
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@available(*, deprecated, message: "Please use `connection == .wifi`")
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var isReachableViaWiFi: Bool {
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return connection == .wifi
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}
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var description: String {
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return flags?.description ?? "unavailable flags"
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}
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@ -233,7 +129,6 @@ fileprivate extension Reachability {
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try reachabilitySerialQueue.sync { [unowned self] in
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var flags = SCNetworkReachabilityFlags()
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if !SCNetworkReachabilityGetFlags(self.reachabilityRef, &flags) {
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self.stopNotifier()
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throw ReachabilityError.unableToGetFlags(SCError())
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}
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@ -307,9 +202,6 @@ extension SCNetworkReachabilityFlags {
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var isDirectFlagSet: Bool {
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return contains(.isDirect)
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}
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var isConnectionRequiredAndTransientFlagSet: Bool {
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return intersection([.connectionRequired, .transientConnection]) == [.connectionRequired, .transientConnection]
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}
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var description: String {
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let W = isOnWWANFlagSet ? "W" : "-"
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@ -325,44 +217,3 @@ extension SCNetworkReachabilityFlags {
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return "\(W)\(R) \(c)\(t)\(i)\(C)\(D)\(l)\(d)"
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}
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}
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/**
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`ReachabilityWeakifier` weakly wraps the `Reachability` class
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in order to break retain cycles when interacting with CoreFoundation.
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CoreFoundation callbacks expect a pair of retain/release whenever an
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opaque `info` parameter is provided. These callbacks exist to guard
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against memory management race conditions when invoking the callbacks.
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#### Race Condition
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If we passed `SCNetworkReachabilitySetCallback` a direct reference to our
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`Reachability` class without also providing corresponding retain/release
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callbacks, then a race condition can lead to crashes when:
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- `Reachability` is deallocated on thread X
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- A `SCNetworkReachability` callback(s) is already in flight on thread Y
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#### Retain Cycle
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If we pass `Reachability` to CoreFoundtion while also providing retain/
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release callbacks, we would create a retain cycle once CoreFoundation
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retains our `Reachability` class. This fixes the crashes and his how
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CoreFoundation expects the API to be used, but doesn't play nicely with
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Swift/ARC. This cycle would only be broken after manually calling
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`stopNotifier()` — `deinit` would never be called.
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#### ReachabilityWeakifier
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By providing both retain/release callbacks and wrapping `Reachability` in
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a weak wrapper, we:
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- interact correctly with CoreFoundation, thereby avoiding a crash.
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See "Memory Management Programming Guide for Core Foundation".
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- don't alter the public API of `Reachability.swift` in any way
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- still allow for automatic stopping of the notifier on `deinit`.
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*/
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private class ReachabilityWeakifier {
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weak var reachability: Reachability?
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init(reachability: Reachability) {
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self.reachability = reachability
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}
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}
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