81 lines
2.8 KiB
Swift
81 lines
2.8 KiB
Swift
// Copyright © 2022 Rangeproof Pty Ltd. All rights reserved.
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import UIKit
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/// This custom UITableView gives us two convenience behaviours:
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///
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/// 1. It allows us to lock the contentOffset to a specific value - it's currently used to prevent the ConversationVC first
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/// responder resignation from making the MediaGalleryDetailViewController transition from looking buggy (ie. the table
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/// scrolls down with the resignation during the transition)
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///
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/// 2. It allows us to provode a callback which gets triggered if a condition closure returns true - it's currently used to prevent
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/// the table view from jumping when inserting new pages at the top of a conversation screen
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public class InsetLockableTableView: UITableView {
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public var lockContentOffset: Bool = false {
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didSet {
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guard !lockContentOffset else { return }
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self.contentOffset = newOffset
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}
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}
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public var oldOffset: CGPoint = .zero
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public var newOffset: CGPoint = .zero
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private var callbackCondition: ((Int, [Int], CGSize) -> Bool)?
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private var afterLayoutSubviewsCallback: (() -> ())?
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public override func layoutSubviews() {
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self.newOffset = self.contentOffset
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// Store the callback locally to prevent infinite loops
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var callback: (() -> ())?
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if self.checkCallbackCondition() {
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callback = self.afterLayoutSubviewsCallback
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self.afterLayoutSubviewsCallback = nil
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}
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guard !lockContentOffset else {
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self.contentOffset = CGPoint(
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x: newOffset.x,
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y: oldOffset.y
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)
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super.layoutSubviews()
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callback?()
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return
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}
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super.layoutSubviews()
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callback?()
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self.oldOffset = self.contentOffset
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}
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// MARK: - Functions
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public func afterNextLayoutSubviews(
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when condition: @escaping (Int, [Int], CGSize) -> Bool,
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then callback: @escaping () -> ()
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) {
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self.callbackCondition = condition
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self.afterLayoutSubviewsCallback = callback
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}
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private func checkCallbackCondition() -> Bool {
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guard self.callbackCondition != nil else { return false }
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let numSections: Int = self.numberOfSections
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let numRowInSections: [Int] = (0..<numSections)
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.map { self.numberOfRows(inSection: $0) }
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// Store the layout info locally so if they pass we can clear the states before running to
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// prevent layouts within the callbacks from triggering infinite loops
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guard self.callbackCondition?(numSections, numRowInSections, self.contentSize) == true else {
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return false
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}
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self.callbackCondition = nil
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return true
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}
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}
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