add PullUpToMarkAsReadTableViewController

iOS/MasterTimeline/PullUpToMarkAsReadTableViewController.swift

@@ -0,0 +1,149 @@
+//
+//  PullUpToMarkAsReadTableViewController.swift
+//  NetNewsWire-iOS
+//
+//  Created by Rob Everhardt on 17-11-2021.
+//  Copyright © 2021 Ranchero Software. All rights reserved.
+//
+
+import UIKit
+
+
+class PullUpToMarkAsReadTableViewController: UITableViewController {
+	private let textPull = "Pull up to mark as read"
+	private let textRelease = "Release to mark as read"
+	private let textMarkingAsRead = "Marking as read..."
+	private let pullUpToMarkAsReadFooterHeight = 52.0
+
+	public var isMarkingAsRead = false
+	public var isDragging = false
+	
+	private var textLabel: UILabel?
+
+	override func viewDidAppear(_ animated: Bool) {
+		super.viewDidAppear(animated)
+		addPullUpToMarkAsReadFooter()
+	}
+
+	func addPullUpToMarkAsReadFooter() {
+		let markAsReadFooterView = UIView.init(frame: CGRect(
+			x: 0.0,
+			y: view.frame.size.height - view.safeAreaInsets.bottom - pullUpToMarkAsReadFooterHeight,
+			width: view.frame.size.width,
+			height: pullUpToMarkAsReadFooterHeight
+		))
+		
+		markAsReadFooterView.backgroundColor = UIColor.clear
+		
+		let label = UILabel.init(frame: CGRect(
+			x: 0.0,
+			y: 0.0,
+			width: view.frame.size.width,
+			height: pullUpToMarkAsReadFooterHeight
+		))
+		label.backgroundColor = UIColor.clear
+		label.font = UIFont.boldSystemFont(ofSize: 12)
+		label.textAlignment = NSTextAlignment.center
+		
+		textLabel = label
+		markAsReadFooterView.addSubview(label)
+		
+//		self.tableView.addSubview(markAsReadFooterView)
+		let backgroundView = UIView()
+		backgroundView.addSubview(markAsReadFooterView)
+		self.tableView.backgroundView = backgroundView
+	}
+	
+	override func scrollViewWillBeginDragging(_ scrollView: UIScrollView) {
+		if (isMarkingAsRead) {
+			return
+		}
+		isDragging = true
+	}
+
+	override func scrollViewDidScroll(_ scrollView: UIScrollView) {
+		guard let label = textLabel else {
+			return
+		}
+		let visibleHeight = view.frame.size.height -
+			view.safeAreaInsets.top
+			- view.safeAreaInsets.bottom
+		let currentOffset = scrollView.contentOffset.y + view.safeAreaInsets.top
+		let scrolledOutOfViewWhenBottomIsReached = max(scrollView.contentSize.height - visibleHeight,0)
+		let pullUpVisibleHeight = max(currentOffset - scrolledOutOfViewWhenBottomIsReached,0)
+		
+		if (isMarkingAsRead) {
+			// Update the content inset, good for section headers
+			if (pullUpVisibleHeight < pullUpToMarkAsReadFooterHeight) {
+				self.tableView.contentInset = UIEdgeInsets.init(
+					top: 0,
+					left: 0,
+					bottom: pullUpVisibleHeight,
+					right: 0
+				);
+			}
+		} else if (isDragging && scrollView.contentOffset.y > 0) {
+			// Update the label
+			UIView.animate(withDuration: 0.25) {
+				if (pullUpVisibleHeight > self.pullUpToMarkAsReadFooterHeight) {
+					// User is scrolling above the header
+					label.text = self.textRelease;
+				} else {
+					// User is scrolling somewhere within the header
+					label.text = self.textPull;
+				}
+			}
+		}
+	}
+	
+	override func scrollViewDidEndDragging(_ scrollView: UIScrollView, willDecelerate decelerate: Bool) {
+		if (isMarkingAsRead) {
+			return
+		}
+		isDragging = false
+		
+		let visibleHeight = view.frame.size.height -
+			view.safeAreaInsets.top
+			- view.safeAreaInsets.bottom
+		let currentOffset = scrollView.contentOffset.y + view.safeAreaInsets.top
+		let scrolledOutOfViewWhenBottomIsReached = max(scrollView.contentSize.height - visibleHeight,0)
+		let pullUpVisibleHeight = max(currentOffset - scrolledOutOfViewWhenBottomIsReached,0)
+		
+		if (pullUpVisibleHeight > pullUpToMarkAsReadFooterHeight) {
+			startMarkingAsRead()
+		}
+	}
+	
+	func startMarkingAsRead() {
+		isMarkingAsRead = true
+		UIView.animate(withDuration: 0.25) {
+			self.tableView.contentInset =  UIEdgeInsets.init(
+				top: 0,
+				left: 0,
+				bottom: self.pullUpToMarkAsReadFooterHeight,
+				right: 0
+			);
+			if let label = self.textLabel {
+				label.text = self.textMarkingAsRead
+			}
+		}
+		
+		markAsRead()
+	}
+
+	func stopMarkingAsRead() {
+		isMarkingAsRead = false
+		if let label = textLabel {
+			label.text = textPull
+		}
+		self.tableView.contentInset = UIEdgeInsets.zero
+	}
+	
+	func markAsRead() {
+		// to override by implementation, which should also call stopMarkingAsRead when done
+
+		DispatchQueue.main.asyncAfter(deadline: .now() + 0.5) {
+			self.stopMarkingAsRead()
+		}
+	}
+}