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Add a drop-in replacement for UIViewController.present working with M…
…MMNavigationStack
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Sources/MMMCommonUI/UIViewController+MMMNavigationStack.swift
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| // | ||
| // Starbucks App. | ||
| // Copyright (c) 2023 MediaMonks. All rights reserved. | ||
| // | ||
|
|
||
| import UIKit | ||
| import MMMLog | ||
|
|
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| @objc public protocol MMMNavigationStackHelperToken { | ||
| func markAsDismissed() | ||
| } | ||
|
|
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| extension UIViewController { | ||
|
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| public typealias MMMNavigationDismissRequestCompletion = (_ successfully: Bool) -> Void | ||
| public typealias MMMNavigationDismissRequest = (_ didDismiss: @escaping MMMNavigationDismissRequestCompletion) -> Void | ||
|
|
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| public enum MMMExternalDismissRequest { | ||
| /// Reject all requests to programmatically dismiss the corresponding view controller. | ||
| case decline | ||
| /// It's enough to call ``UIViewController.dismiss(animated:completion:)`` to programmatically dismiss | ||
| /// the corresponding view controller, no extra steps necessary. | ||
| case justDismiss | ||
| /// It's enough to call ``UIViewController.dismiss(animated:completion:)`` followed by a few synchronous | ||
| /// instructions to programmatically dismiss the corresponding view controller. | ||
| case dismissThen(() -> Void) | ||
| /// A custom piece of code is needed to dismiss the corresponding view controller. The code receives a | ||
| /// `didDismiss` that must be eventually called after the dismissal completes (or cannot be completed). | ||
| case custom(MMMNavigationDismissRequest) | ||
| } | ||
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| /// A drop-in replacement for `UIViewController.present(_:animated:completion:)` recording the presentation | ||
| /// with ``MMMNavigationStack`` to properly dismiss the view controller when the app needs to programmatically | ||
| /// unwind the current UI flow to navigate somewhere else (e.g. while opening a deep link). | ||
| /// | ||
| /// - Parameter onExternalDismissRequest: | ||
| /// Describes what needs to be done to programmatically dismiss the view controller being presented | ||
| /// while programmatically unwinding the UI. | ||
| /// | ||
| /// - Returns: | ||
| /// The token that can be used to properly update ``MMMNavigationStack`` in case the view controller cannot | ||
| /// be dismissed via matching ``UIViewController.mmm_dismiss(animated:completion:)``. | ||
| /// | ||
| /// This method needs to be used in conjunction with ``UIViewController.mmm_dismiss(animated:completion:)`` replacing | ||
| /// ``UIViewController.dismiss(animated:completion:)`` or, when that's not possible, while timely marking | ||
| /// the view controller as dismissed via a call to ``MMMNavigationStackHelperToken.markAsDismissed()`` on the | ||
| /// returned token. | ||
| @discardableResult | ||
| public func mmm_present( | ||
| _ viewController: UIViewController, | ||
| animated: Bool, | ||
| onExternalDismissRequest: MMMExternalDismissRequest, | ||
| completion: (() -> Void)? = nil | ||
| ) -> MMMNavigationStackHelperToken? { | ||
|
|
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| present(viewController, animated: animated, completion: completion) | ||
|
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| // Assuming that `presentingViewController` is set after the above call. | ||
| guard let presentingViewController = viewController.presentingViewController else { | ||
| assertionFailure("Could not present \(MMMTypeName(viewController)) via \(MMMTypeName(self))?") | ||
| return nil | ||
| } | ||
|
|
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| return MMMNavigationStackHelper.instanceFor(presentingViewController).push( | ||
| viewController: viewController, | ||
| externalDismissRequest: { | ||
| switch onExternalDismissRequest { | ||
| case .justDismiss: | ||
| return { [weak viewController] didDismiss in | ||
| guard let viewController = viewController else { | ||
| assertionFailure("Trying to dismiss a view controller that is gone already?") | ||
| return | ||
| } | ||
| viewController.mmm_dismiss(animated: true) { | ||
| didDismiss(true) | ||
| } | ||
| } | ||
| case .dismissThen(let callback): | ||
| return { [weak viewController] didDismiss in | ||
| guard let viewController = viewController else { | ||
| assertionFailure("Trying to dismiss a view controller that is gone already?") | ||
| return | ||
| } | ||
| viewController.mmm_dismiss(animated: true) { | ||
| callback() | ||
| didDismiss(true) | ||
| } | ||
| } | ||
| case .decline: | ||
| return { didDismiss in | ||
| didDismiss(false) | ||
| } | ||
| case .custom(let callback): | ||
| return callback | ||
| } | ||
| }() | ||
| ) | ||
| } | ||
|
|
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| /// ObjC-friendly version of ``mmm_present(_:animated:onExternalDismissRequest:completion:)``. | ||
| @objc(mmm_presentViewController:animated:onExternalDismissRequest:completion:) | ||
| public func mmm_present( | ||
| _ viewController: UIViewController, | ||
| animated: Bool, | ||
| onExternalDismissRequest: @escaping MMMNavigationDismissRequest, | ||
| completion: (() -> Void)? = nil | ||
| ) -> MMMNavigationStackHelperToken? { | ||
| self.mmm_present( | ||
| viewController, | ||
| animated: animated, | ||
| onExternalDismissRequest: .custom(onExternalDismissRequest), | ||
| completion: completion | ||
| ) | ||
| } | ||
|
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| /// A drop-in replacement for ``UIViewController.dismiss(animated:completion:)`` to be used in conjunction with | ||
| /// ``mmm_present(_:animated:onExternalDismissRequest:completion:)``. Check the latter for more info. | ||
| /// | ||
| /// It should be safe to call this even for the view controllers that were not presented via | ||
| /// ``mmm_present(_:animated:onExternalDismissRequest:completion:)`` (though you'll get a trace in the logs). | ||
| @objc(mmm_dismissAnimated:completion:) | ||
| public func mmm_dismiss( | ||
| animated flag: Bool, | ||
| completion: (() -> Void)? = nil | ||
| ) { | ||
| // I am not quite sure about the logic of dismiss() call, but this should be enough for our use cases. | ||
| let viewControllerToBeDismissed = self.presentedViewController ?? self | ||
| guard let presentingViewController = viewControllerToBeDismissed.presentingViewController else { | ||
| assertionFailure("Could not figure out the presenting view controller for \(MMMTypeName(viewControllerToBeDismissed))") | ||
| self.dismiss(animated: flag, completion: completion) | ||
| return | ||
| } | ||
|
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| self.dismiss(animated: flag) { | ||
| MMMNavigationStackHelper.instanceFor(presentingViewController).pop(viewControllerToBeDismissed) | ||
| completion?() | ||
| } | ||
| } | ||
|
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| /// Should be used to properly update the state of ``MMMNavigationStack`` after a view controller presented | ||
| /// via ``UIViewController.mmm_present(_:animated:onExternalDismissRequest:completion:)`` is dismissed without | ||
| /// the use of a matching ``UIViewController.mmm_dismiss(animated:completion:)`` call. | ||
| /// | ||
| /// This is an alternative to ``MMMNavigationStackHelperToken.markAsDismissed()`` called on the token | ||
| /// returned by ``UIViewController.mmm_present(_:animated:onExternalDismissRequest:completion:)``, | ||
| /// which might not always be convenient. Note however that this must to be called on the actual presenting | ||
| /// view controller which is not always the same as the view controller receiving the `mmm_present` call! | ||
| @objc(mmm_markViewControllerAsDismissed:) | ||
| public func mmm_markAsDismissed(_ viewController: UIViewController) { | ||
| MMMNavigationStackHelper.instanceFor(self).pop(viewController) | ||
| } | ||
| } | ||
|
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| private class MMMNavigationStackHelper: NSObject, MMMNavigationStackItemDelegate, MMMLogSource { | ||
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| public let logContext: String = "MMMNavigationStackHelper" | ||
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| private static var key: Int = 110 // In percents. | ||
|
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| public static func instanceFor(_ obj: NSObject) -> MMMNavigationStackHelper { | ||
| if let helper = objc_getAssociatedObject(obj, &key) as? MMMNavigationStackHelper { | ||
| return helper | ||
| } | ||
| let helper = MMMNavigationStackHelper() | ||
| objc_setAssociatedObject(obj, &key, helper, .OBJC_ASSOCIATION_RETAIN_NONATOMIC) | ||
| return helper | ||
| } | ||
|
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| private class Record { | ||
|
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| public let navigationItem: MMMNavigationStackItem | ||
| public private(set) weak var viewController: UIViewController? | ||
| public let externalDismissRequest: UIViewController.MMMNavigationDismissRequest | ||
|
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| internal init( | ||
| navigationItem: MMMNavigationStackItem, | ||
| viewController: UIViewController?, | ||
| externalDismissRequest: @escaping UIViewController.MMMNavigationDismissRequest | ||
| ) { | ||
| self.navigationItem = navigationItem | ||
| self.viewController = viewController | ||
| self.externalDismissRequest = externalDismissRequest | ||
| } | ||
| } | ||
|
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| private var records: [Record] = [] | ||
|
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| public func push( | ||
| viewController: UIViewController, | ||
| externalDismissRequest: @escaping UIViewController.MMMNavigationDismissRequest | ||
| ) -> MMMNavigationStackHelperToken? { | ||
|
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| let item = MMMNavigationStack.shared().pushItem( | ||
| name: MMMTypeName(viewController), | ||
| delegate: self, | ||
| controller: viewController | ||
| ) | ||
| guard let item else { | ||
| // It's possible that the push is not successful, this will be logged by the stack. | ||
| return nil | ||
| } | ||
|
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| let record = Record( | ||
| navigationItem: item, | ||
| viewController: viewController, | ||
| externalDismissRequest: externalDismissRequest | ||
| ) | ||
|
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| records.append(record) | ||
|
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| return Token(helper: self, record: record) | ||
| } | ||
|
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| public func pop(_ viewController: UIViewController) { | ||
|
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| if let recordPoppingNow { | ||
| if recordPoppingNow.viewController === viewController { | ||
| // The record is already removed as part of the pop request, nothing to do here. | ||
| return | ||
| } else { | ||
| MMMLogError(self, "Trying to remove a record for a \(MMMTypeName(viewController)) while popping a different instance (\(MMMTypeName(recordPoppingNow.viewController)))") | ||
| assertionFailure() | ||
| // It would be a weird case, but let it continue in production. | ||
| } | ||
| } | ||
|
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| guard let record = records.last, record.viewController === viewController else { | ||
| MMMLogTrace(self, "Trying to remove a record for a \(MMMTypeName(viewController)) when it's not on top or does not exist") | ||
| // Not asserting here because we want mmm_dismiss() to be safe to call with view controllers | ||
| // that were not presented with mmm_present. | ||
| return | ||
| } | ||
| record.navigationItem.didPop() | ||
| records.removeLast() | ||
| } | ||
|
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| private var recordPoppingNow: Record? | ||
|
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| public func pop(_ item: MMMNavigationStackItem) { | ||
|
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| guard | ||
| let record = records.last, | ||
| record.navigationItem === item, | ||
| recordPoppingNow == nil | ||
| else { | ||
| MMMLogError(self, "Trying to pop an item that's not on top in our records or while popping something already") | ||
| item.didFailToPop() | ||
| assertionFailure() | ||
| return | ||
| } | ||
|
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| recordPoppingNow = record | ||
| records.removeLast() | ||
|
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| record.externalDismissRequest { [weak self] succeeded in | ||
|
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| guard let self = self else { return } | ||
|
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| guard self.recordPoppingNow === record else { | ||
| // Can happen in case markAsPopped was called in the meantime. | ||
| return | ||
| } | ||
|
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| self.recordPoppingNow = nil | ||
|
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| if succeeded { | ||
| record.navigationItem.didPop() | ||
| } else { | ||
| record.navigationItem.didFailToPop() | ||
| } | ||
| } | ||
| } | ||
|
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| private func markAsPopped(_ record: Record) { | ||
|
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| records.removeAll { $0 === record } | ||
|
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| if recordPoppingNow === record { | ||
| recordPoppingNow = nil | ||
| } | ||
|
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| record.navigationItem.didPop() | ||
| } | ||
|
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| @objc private class Token: NSObject, MMMNavigationStackHelperToken { | ||
|
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| private let helper: MMMNavigationStackHelper | ||
| private let record: Record | ||
|
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| public init(helper: MMMNavigationStackHelper, record: Record) { | ||
| self.helper = helper | ||
| self.record = record | ||
| } | ||
|
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| public func markAsDismissed() { | ||
| helper.markAsPopped(record) | ||
| } | ||
| } | ||
| } |
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