4f06a6d8a5
The block-based API returns a token that needs to be explicitly unregistered, *and* the block should not capture 'self' strongly. The fixes in this PR come in three flavors: 1. Switch to the selector-based API, sometimes taking advantage of the fact that extra arguments to an Objective-C method can be safely discarded (because they are passed at +0). 2. Save the observer token and unregister in deinit. 3. Comment why it's safe to leave the observer registered forever in this particular case.
113 lines
2.9 KiB
Swift
113 lines
2.9 KiB
Swift
//
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// Copyright (c) 2022 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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self,
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selector: #selector(fireEvent),
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name: SSKReachability.owsReachabilityDidChange,
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object: nil)
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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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@objc
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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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