113 lines
2.9 KiB
Swift
113 lines
2.9 KiB
Swift
//
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// Copyright (c) 2021 Open Whisper Systems. All rights reserved.
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//
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import Foundation
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// This class can be used to coordinate the refresh of a
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// value obtained from the network.
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@objc
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public class RefreshEvent: NSObject {
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public typealias Block = () -> Void
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private let block: Block
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private let refreshInterval: TimeInterval
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private var refreshTimer: Timer?
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// The block will be performed with a rough frequency of refreshInterval.
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//
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// It will not be performed if the app isn't ready, the user isn't registered,
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// if the app isn't the main app, if the app isn't active.
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//
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// It will also be performed immediately if any of the conditions change.
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public required init(refreshInterval: TimeInterval,
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block: @escaping Block) {
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self.refreshInterval = refreshInterval
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self.block = block
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super.init()
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AppReadiness.runNowOrWhenAppDidBecomeReadyAsync { [weak self] in
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self?.ensureRefreshTimer()
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}
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NotificationCenter.default.addObserver(
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self,
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selector: #selector(didEnterBackground),
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name: .OWSApplicationDidEnterBackground,
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object: nil
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)
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NotificationCenter.default.addObserver(
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self,
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selector: #selector(didBecomeActive),
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name: .OWSApplicationDidBecomeActive,
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object: nil
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)
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NotificationCenter.default.addObserver(
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forName: SSKReachability.owsReachabilityDidChange,
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object: nil,
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queue: nil) { [weak self] _ in
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self?.fireEvent()
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}
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}
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private var canFire: Bool {
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guard AppReadiness.isAppReady,
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CurrentAppContext().isMainAppAndActive,
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tsAccountManager.isRegisteredAndReady else {
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return false
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}
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return true
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}
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private func fireEvent() {
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guard canFire else {
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return
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}
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block()
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}
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@objc
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private func didEnterBackground() {
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AssertIsOnMainThread()
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ensureRefreshTimer()
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}
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@objc
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private func didBecomeActive() {
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AssertIsOnMainThread()
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ensureRefreshTimer()
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}
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private func ensureRefreshTimer() {
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guard canFire else {
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stopRefreshTimer()
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return
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}
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startRefreshTimer()
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}
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private func stopRefreshTimer() {
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refreshTimer?.invalidate()
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refreshTimer = nil
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}
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private func startRefreshTimer() {
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guard refreshTimer == nil else {
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return
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}
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refreshTimer = WeakTimer.scheduledTimer(timeInterval: refreshInterval,
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target: self,
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userInfo: nil,
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repeats: true) { [weak self] _ in
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self?.fireEvent()
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}
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fireEvent()
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}
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}
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