Один из возможных способов рисования вкладок - это использование NSCollectionView. Вот пример Swift 4:
Класс TabViewStackController содержит TabViewController, предварительно настроенный со стилем .unspecified и пользовательский TabBarView.
class TabViewStackController: ViewController {
private lazy var tabBarView = TabBarView().autolayoutView()
private lazy var containerView = View().autolayoutView()
private lazy var tabViewController = TabViewController()
private let tabs: [String] = (0 ..< 14).map { "TabItem # \($0)" }
override func setupUI() {
view.addSubviews(tabBarView, containerView)
embedChildViewController(tabViewController, container: containerView)
}
override func setupLayout() {
LayoutConstraint.withFormat("|-[*]-|", forEveryViewIn: containerView, tabBarView).activate()
LayoutConstraint.withFormat("V:|-[*]-[*]-|", tabBarView, containerView).activate()
}
override func setupHandlers() {
tabBarView.eventHandler = { [weak self] in
switch $0 {
case .select(let item):
self?.tabViewController.process(item: item)
}
}
}
override func setupDefaults() {
tabBarView.tabs = tabs
if let item = tabs.first {
tabBarView.select(item: item)
tabViewController.process(item: item)
}
}
}
Класс TabBarView содержит CollectionView, который представляет вкладки.
class TabBarView: View {
public enum Event {
case select(String)
}
public var eventHandler: ((Event) -> Void)?
private let cellID = NSUserInterfaceItemIdentifier(rawValue: "cid.tabView")
public var tabs: [String] = [] {
didSet {
collectionView.reloadData()
}
}
private lazy var collectionView = TabBarCollectionView()
private let tabBarHeight: CGFloat = 28
private (set) lazy var scrollView = TabBarScrollView(collectionView: collectionView).autolayoutView()
override var intrinsicContentSize: NSSize {
let size = CGSize(width: NSView.noIntrinsicMetric, height: tabBarHeight)
return size
}
override func setupHandlers() {
collectionView.delegate = self
}
override func setupDataSource() {
collectionView.dataSource = self
collectionView.register(TabBarTabViewItem.self, forItemWithIdentifier: cellID)
}
override func setupUI() {
addSubviews(scrollView)
wantsLayer = true
let gridLayout = NSCollectionViewGridLayout()
gridLayout.maximumNumberOfRows = 1
gridLayout.minimumItemSize = CGSize(width: 115, height: tabBarHeight)
gridLayout.maximumItemSize = gridLayout.minimumItemSize
collectionView.collectionViewLayout = gridLayout
}
override func setupLayout() {
LayoutConstraint.withFormat("|[*]|", scrollView).activate()
LayoutConstraint.withFormat("V:|[*]|", scrollView).activate()
}
}
extension TabBarView {
func select(item: String) {
if let index = tabs.index(of: item) {
let ip = IndexPath(item: index, section: 0)
if collectionView.item(at: ip) != nil {
collectionView.selectItems(at: [ip], scrollPosition: [])
}
}
}
}
extension TabBarView: NSCollectionViewDataSource {
func collectionView(_ collectionView: NSCollectionView, numberOfItemsInSection section: Int) -> Int {
return tabs.count
}
func collectionView(_ collectionView: NSCollectionView, itemForRepresentedObjectAt indexPath: IndexPath) -> NSCollectionViewItem {
let tabItem = tabs[indexPath.item]
let cell = collectionView.makeItem(withIdentifier: cellID, for: indexPath)
if let cell = cell as? TabBarTabViewItem {
cell.configure(title: tabItem)
}
return cell
}
}
extension TabBarView: NSCollectionViewDelegate {
func collectionView(_ collectionView: NSCollectionView, didSelectItemsAt indexPaths: Set<IndexPath>) {
if let first = indexPaths.first {
let item = tabs[first.item]
eventHandler?(.select(item))
}
}
}
Класс TabViewController, предварительно настроенный со стилем .unspecified
class TabViewController: GenericTabViewController<String> {
override func viewDidLoad() {
super.viewDidLoad()
transitionOptions = []
tabStyle = .unspecified
}
func process(item: String) {
if index(of: item) != nil {
select(itemIdentifier: item)
} else {
let vc = TabContentController(content: item)
let tabItem = GenericTabViewItem(identifier: item, viewController: vc)
addTabViewItem(tabItem)
select(itemIdentifier: item)
}
}
}
Остальные занятия.
class TabBarCollectionView: CollectionView {
override func setupUI() {
isSelectable = true
allowsMultipleSelection = false
allowsEmptySelection = false
backgroundView = View(backgroundColor: .magenta)
backgroundColors = [.clear]
}
}
class TabBarScrollView: ScrollView {
override func setupUI() {
borderType = .noBorder
backgroundColor = .clear
drawsBackground = false
horizontalScrollElasticity = .none
verticalScrollElasticity = .none
automaticallyAdjustsContentInsets = false
horizontalScroller = InvisibleScroller()
}
}
// Disabling scroll view indicators.
// See: https://stackoverflow.com/questions/9364953/hide-scrollers-while-leaving-scrolling-itself-enabled-in-nsscrollview
private class InvisibleScroller: Scroller {
override class var isCompatibleWithOverlayScrollers: Bool {
return true
}
override class func scrollerWidth(for controlSize: NSControl.ControlSize, scrollerStyle: NSScroller.Style) -> CGFloat {
return CGFloat.leastNormalMagnitude // Dimension of scroller is equal to `FLT_MIN`
}
override func setupUI() {
// Below assignments not really needed, but why not.
scrollerStyle = .overlay
alphaValue = 0
}
}
class TabBarTabViewItem: CollectionViewItem {
private lazy var titleLabel = Label().autolayoutView()
override var isSelected: Bool {
didSet {
if isSelected {
titleLabel.font = Font.semibold(size: 10)
contentView.backgroundColor = .red
} else {
titleLabel.font = Font.regular(size: 10.2)
contentView.backgroundColor = .blue
}
}
}
override func setupUI() {
view.addSubviews(titleLabel)
view.wantsLayer = true
titleLabel.maximumNumberOfLines = 1
}
override func setupDefaults() {
isSelected = false
}
func configure(title: String) {
titleLabel.text = title
titleLabel.textColor = .white
titleLabel.alignment = .center
}
override func setupLayout() {
LayoutConstraint.withFormat("|-[*]-|", titleLabel).activate()
LayoutConstraint.withFormat("V:|-(>=4)-[*]", titleLabel).activate()
LayoutConstraint.centerY(titleLabel).activate()
}
}
class TabContentController: ViewController {
let content: String
private lazy var titleLabel = Label().autolayoutView()
init(content: String) {
self.content = content
super.init()
}
required init?(coder: NSCoder) {
fatalError()
}
override func setupUI() {
contentView.addSubview(titleLabel)
titleLabel.text = content
contentView.backgroundColor = .green
}
override func setupLayout() {
LayoutConstraint.centerXY(titleLabel).activate()
}
}
Вот как это выглядит:
