136 lines
5.3 KiB
Swift
136 lines
5.3 KiB
Swift
// Copyright © 2020 Metabolist. All rights reserved.
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import Combine
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import UIKit
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final class LoadMoreView: UIView {
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private let leadingArrowImageView = UIImageView()
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private let trailingArrowImageView = UIImageView()
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private let label = UILabel()
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private let activityIndicatorView = UIActivityIndicatorView()
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private var loadMoreConfiguration: LoadMoreContentConfiguration
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private var loadingCancellable: AnyCancellable?
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private var directionChange = LoadMoreView.directionChangeMax
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init(configuration: LoadMoreContentConfiguration) {
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self.loadMoreConfiguration = configuration
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super.init(frame: .zero)
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initialSetup()
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applyLoadMoreConfiguration()
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}
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@available(*, unavailable)
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required init?(coder: NSCoder) {
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fatalError("init(coder:) has not been implemented")
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}
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}
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extension LoadMoreView {
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static var estimatedHeight: CGFloat {
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.defaultSpacing * 2 + UIFont.preferredFont(forTextStyle: .title2).lineHeight
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}
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func directionChanged(up: Bool) {
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guard !loadMoreConfiguration.viewModel.loading else { return }
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if up, directionChange < Self.directionChangeMax {
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directionChange += Self.directionChangeIncrement
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} else if !up, directionChange > -Self.directionChangeMax {
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directionChange -= Self.directionChangeIncrement
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}
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updateDirectionChange(animated: false)
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}
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func finalizeDirectionChange() {
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directionChange = directionChange > 0 ? Self.directionChangeMax : -Self.directionChangeMax
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updateDirectionChange(animated: true)
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}
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}
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extension LoadMoreView: UIContentView {
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var configuration: UIContentConfiguration {
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get { loadMoreConfiguration }
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set {
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guard let loadMoreConfiguration = newValue as? LoadMoreContentConfiguration else { return }
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self.loadMoreConfiguration = loadMoreConfiguration
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applyLoadMoreConfiguration()
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}
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}
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}
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private extension LoadMoreView {
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static let directionChangeMax = CGFloat.pi
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static let directionChangeIncrement = CGFloat.pi / 10
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func initialSetup() {
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for arrowImageView in [leadingArrowImageView, trailingArrowImageView] {
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addSubview(arrowImageView)
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arrowImageView.translatesAutoresizingMaskIntoConstraints = false
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arrowImageView.image = UIImage(
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systemName: "arrow.up",
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withConfiguration: UIImage.SymbolConfiguration(
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pointSize: UIFont.preferredFont(forTextStyle: .title2).pointSize))
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arrowImageView.setContentHuggingPriority(.required, for: .horizontal)
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}
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addSubview(label)
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label.translatesAutoresizingMaskIntoConstraints = false
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label.textAlignment = .center
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label.font = .preferredFont(forTextStyle: .title2)
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label.adjustsFontForContentSizeCategory = true
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label.textColor = label.tintColor
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label.text = NSLocalizedString("load-more", comment: "")
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label.setContentHuggingPriority(.defaultLow, for: .horizontal)
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addSubview(activityIndicatorView)
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activityIndicatorView.translatesAutoresizingMaskIntoConstraints = false
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activityIndicatorView.hidesWhenStopped = true
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NSLayoutConstraint.activate([
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leadingArrowImageView.leadingAnchor.constraint(equalTo: readableContentGuide.leadingAnchor),
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leadingArrowImageView.topAnchor.constraint(equalTo: readableContentGuide.topAnchor),
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leadingArrowImageView.bottomAnchor.constraint(equalTo: readableContentGuide.bottomAnchor),
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label.leadingAnchor.constraint(equalTo: leadingArrowImageView.trailingAnchor),
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label.topAnchor.constraint(greaterThanOrEqualTo: readableContentGuide.topAnchor),
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label.bottomAnchor.constraint(greaterThanOrEqualTo: readableContentGuide.bottomAnchor),
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label.trailingAnchor.constraint(equalTo: trailingArrowImageView.leadingAnchor),
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trailingArrowImageView.topAnchor.constraint(equalTo: readableContentGuide.topAnchor),
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trailingArrowImageView.bottomAnchor.constraint(equalTo: readableContentGuide.bottomAnchor),
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trailingArrowImageView.trailingAnchor.constraint(equalTo: readableContentGuide.trailingAnchor),
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activityIndicatorView.centerXAnchor.constraint(equalTo: centerXAnchor),
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activityIndicatorView.centerYAnchor.constraint(equalTo: centerYAnchor)
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])
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}
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func applyLoadMoreConfiguration() {
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loadingCancellable = loadMoreConfiguration.viewModel.$loading.sink { [weak self] in
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guard let self = self else { return }
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self.label.isHidden = $0
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$0 ? self.activityIndicatorView.startAnimating() : self.activityIndicatorView.stopAnimating()
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}
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}
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func updateDirectionChange(animated: Bool) {
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if animated {
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UIView.animate(withDuration: 0.1) {
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self.performDirectionChangeUpdates()
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}
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} else {
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self.performDirectionChangeUpdates()
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}
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}
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func performDirectionChangeUpdates() {
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loadMoreConfiguration.viewModel.direction = directionChange > 0 ? .up : .down
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leadingArrowImageView.transform = CGAffineTransform(rotationAngle: .pi / 2 - directionChange / 2)
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trailingArrowImageView.transform = CGAffineTransform(rotationAngle: -.pi / 2 + directionChange / 2)
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}
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}
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