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PageViewController.swift 12KB

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  1. //
  2. // PageViewController.swift
  3. // PaiAi
  4. //
  5. // Created by FFIB on 2018/12/6.
  6. // Copyright © 2018 FFIB. All rights reserved.
  7. //
  8. import UIKit
  9. private let baseTag = 55161750
  10. open class PageViewController: UIViewController {
  11. private enum ScrollDirection {
  12. case left
  13. case right
  14. }
  15. private var contentRect = CGRect.zero
  16. //animation auxiliary
  17. private var currentIndex: Int = 0
  18. private var distance: CGFloat = 0
  19. private var currentItem: UILabel?
  20. private var startOffset: CGFloat = 0
  21. private var isBeginScroll: Bool = false
  22. private var menuItemWidths: [CGFloat] = []
  23. private var direction: ScrollDirection = .right
  24. private var sliderConstraint: NSLayoutConstraint?
  25. public private(set) lazy var scrollView: UIScrollView = {
  26. let scrollView = UIScrollView()
  27. scrollView.bounces = false
  28. scrollView.delegate = self
  29. scrollView.isPagingEnabled = true
  30. scrollView.alwaysBounceVertical = false
  31. scrollView.showsVerticalScrollIndicator = false
  32. scrollView.showsHorizontalScrollIndicator = false
  33. return scrollView
  34. }()
  35. public private(set) lazy var menuView: UIView = {
  36. let view = UIView()
  37. return view
  38. }()
  39. public private(set) lazy var sliderView: UIView = {
  40. let view = UIView()
  41. view.layer.cornerRadius = 2.5
  42. view.backgroundColor = option.selectedColor
  43. return view
  44. }()
  45. public var option = PageOption()
  46. public var pageItems = [PageItem]() {
  47. didSet {
  48. DispatchQueue.main.async {
  49. self.setPageItems()
  50. self.setMenuItems()
  51. }
  52. }
  53. }
  54. override open func viewDidLoad() {
  55. super.viewDidLoad()
  56. contentRect = CGRect(x: 0, y: 0, width: view.frame.width, height: view.frame.height)
  57. if #available(iOS 11, *) {
  58. scrollView.contentInsetAdjustmentBehavior = .never
  59. }
  60. constructViewHierarchy()
  61. activateConstraints()
  62. setMenuGestureRecognizer()
  63. }
  64. open override func viewDidLayoutSubviews() {
  65. super.viewDidLayoutSubviews()
  66. cacheMenuItemWidth()
  67. }
  68. private func cacheMenuItemWidth() {
  69. guard menuItemWidths.isEmpty else { return }
  70. menuItemWidths = Array(repeating: 0, count: menuView.subviews.count - 1)
  71. for view in menuView.subviews {
  72. guard let label = view as? UILabel else { continue }
  73. menuItemWidths[label.tag - baseTag] = label.frame.width
  74. }
  75. }
  76. private func constructViewHierarchy() {
  77. navigationItem.titleView = menuView
  78. view.addSubview(scrollView)
  79. menuView.addSubview(sliderView)
  80. }
  81. }
  82. /// set PageItem and MenuItem
  83. fileprivate extension PageViewController {
  84. func setPageItems() {
  85. guard !pageItems.isEmpty else { return }
  86. var navigationBarHeight: CGFloat
  87. if UIApplication.shared.statusBarFrame.height == 44 {
  88. navigationBarHeight = 88
  89. } else {
  90. navigationBarHeight = 64
  91. }
  92. scrollView.contentSize = CGSize(width: contentRect.width * CGFloat(pageItems.count),
  93. height: contentRect.height - navigationBarHeight)
  94. var last: UIView?
  95. for item in pageItems {
  96. addChild(item.viewController)
  97. scrollView.addSubview(item.viewController.view)
  98. item.viewController.view.translatesAutoresizingMaskIntoConstraints = false
  99. let width = item.viewController.view
  100. .widthAnchor
  101. .constraint(equalTo: scrollView.widthAnchor)
  102. let height = item.viewController.view
  103. .heightAnchor
  104. .constraint(equalTo: scrollView.heightAnchor)
  105. let top = item.viewController.view
  106. .topAnchor
  107. .constraint(equalTo: scrollView.topAnchor)
  108. let leading = item.viewController.view
  109. .leadingAnchor
  110. .constraint(equalTo: last?.trailingAnchor ?? scrollView.leadingAnchor)
  111. NSLayoutConstraint.activate([width, height, top, leading])
  112. last = item.viewController.view
  113. }
  114. }
  115. func setMenuItems() {
  116. guard !pageItems.isEmpty else { return }
  117. var last: UILabel?
  118. var width: CGFloat = 0
  119. for (i, item) in pageItems.enumerated() {
  120. let label = UILabel()
  121. label.text = item.title
  122. label.tag = baseTag + i
  123. label.font = option.font
  124. label.textAlignment = .center
  125. label.textColor = option.normalColor
  126. label.translatesAutoresizingMaskIntoConstraints = false
  127. menuView.addSubview(label)
  128. if i == 0 {
  129. label.textColor = option.selectedColor
  130. label.font = UIFont.systemFont(ofSize: option.font.pointSize + 1)
  131. currentItem = label
  132. } else if i == pageItems.count - 1 {
  133. NSLayoutConstraint.activate([label.trailingAnchor
  134. .constraint(equalTo: menuView.trailingAnchor)])
  135. }
  136. NSLayoutConstraint.activate([
  137. label.leadingAnchor.constraint(equalTo: last?.trailingAnchor ?? menuView.leadingAnchor,
  138. constant: last == nil ? 0 : option.spacing),
  139. label.centerYAnchor.constraint(equalTo: menuView.centerYAnchor)])
  140. last = label
  141. if #available(iOS 11, *) { continue }
  142. label.sizeToFit()
  143. width += label.frame.width
  144. }
  145. setSliderViewDetail()
  146. if #available(iOS 11, *) { return }
  147. menuView.frame.size = CGSize(width: width + CGFloat(pageItems.count - 1) * option.spacing, height: 40)
  148. }
  149. func setSliderViewDetail() {
  150. guard let label = menuView.viewWithTag(baseTag) else { return }
  151. sliderConstraint = sliderView.centerXAnchor.constraint(equalTo: label.centerXAnchor)
  152. NSLayoutConstraint.activate([sliderConstraint!])
  153. if #available(iOS 11, *) {
  154. NSLayoutConstraint.activate([sliderView.topAnchor.constraint(equalTo: label.bottomAnchor, constant: 6)])
  155. }
  156. }
  157. }
  158. /// layout
  159. fileprivate extension PageViewController {
  160. func activateConstraints() {
  161. activateConstraintsSliderView()
  162. activateConstraintsScrollView()
  163. }
  164. func activateConstraintsScrollView() {
  165. scrollView.translatesAutoresizingMaskIntoConstraints = false
  166. let top = scrollView.topAnchor.constraint(equalTo: view.topAnchor)
  167. let width = scrollView.widthAnchor.constraint(equalTo: view.widthAnchor)
  168. let bottom = scrollView.bottomAnchor.constraint(equalTo: view.bottomAnchor)
  169. let height = scrollView.heightAnchor.constraint(equalTo: view.heightAnchor)
  170. let leading = scrollView.leadingAnchor.constraint(equalTo: view.leadingAnchor)
  171. let trailing = scrollView.trailingAnchor.constraint(equalTo: view.trailingAnchor)
  172. NSLayoutConstraint.activate([width, height, top, leading, bottom, trailing])
  173. }
  174. func activateConstraintsSliderView() {
  175. sliderView.translatesAutoresizingMaskIntoConstraints = false
  176. NSLayoutConstraint.activate([
  177. sliderView.widthAnchor.constraint(equalToConstant: 5),
  178. sliderView.heightAnchor.constraint(equalToConstant: 5),
  179. sliderView.bottomAnchor.constraint(equalTo: menuView.bottomAnchor, constant: -2)
  180. ])
  181. }
  182. }
  183. /// GuestureRecognizer
  184. fileprivate extension PageViewController {
  185. func setMenuGestureRecognizer() {
  186. let tap = UITapGestureRecognizer(target: self, action: #selector(tapMenu(tap:)))
  187. menuView.addGestureRecognizer(tap)
  188. }
  189. @objc func tapMenu(tap: UITapGestureRecognizer) {
  190. var x = tap.location(in: menuView).x
  191. for (i, width) in menuItemWidths.enumerated() {
  192. x -= (width + option.spacing / 2)
  193. guard x <= 0 else { continue }
  194. if i != currentIndex {
  195. didSelect(i)
  196. }
  197. return
  198. }
  199. }
  200. }
  201. /// UIScrollViewDelegate implementation
  202. extension PageViewController: UIScrollViewDelegate {
  203. public func scrollViewWillBeginDragging(_ scrollView: UIScrollView) {
  204. startOffset = self.scrollView.contentOffset.x
  205. isBeginScroll = true
  206. }
  207. public func scrollViewDidScroll(_ scrollView: UIScrollView) {
  208. guard scrollView.isDragging || scrollView.isDecelerating || scrollView.isTracking else { return }
  209. initializeScrollParameter()
  210. moveSlider(percentage: (self.scrollView.contentOffset.x - startOffset ) / contentRect.width)
  211. }
  212. public func scrollViewDidEndDragging(_ scrollView: UIScrollView, willDecelerate decelerate: Bool) {
  213. guard !decelerate else { return }
  214. pageViewDidEndScroll()
  215. }
  216. public func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
  217. pageViewDidEndScroll()
  218. }
  219. public func scrollViewDidEndScrollingAnimation(_ scrollView: UIScrollView) {
  220. pageViewDidEndScroll()
  221. }
  222. }
  223. /// linkage
  224. fileprivate extension PageViewController {
  225. func didSelect(_ index: Int) {
  226. startOffset = self.scrollView.contentOffset.x
  227. sliderAnimation(index)
  228. didSelectPageItem(index)
  229. }
  230. func initializeScrollParameter() {
  231. if isBeginScroll {
  232. direction = self.scrollView.contentOffset.x - startOffset > 0 ? .right : .left
  233. guard let label = currentItem else { return }
  234. let curr = menuItemWidths[label.tag - baseTag]
  235. switch direction {
  236. case .left:
  237. guard label.tag - baseTag - 1 > 0 else { return }
  238. distance = curr / 2 + menuItemWidths[label.tag - baseTag - 1] / 2 + option.spacing
  239. case .right:
  240. guard label.tag - baseTag + 1 < menuItemWidths.count else { return }
  241. distance = curr / 2 + menuItemWidths[label.tag - baseTag + 1] / 2 + option.spacing
  242. }
  243. isBeginScroll = false
  244. }
  245. }
  246. }
  247. /// menu linkage
  248. fileprivate extension PageViewController {
  249. func moveSlider(percentage: CGFloat) {
  250. sliderConstraint?.constant = percentage * distance
  251. }
  252. func didSelectMenuItem(_ index: Int) {
  253. guard let currentLabel = currentItem,
  254. let label = menuView.viewWithTag(baseTag + index) as? UILabel else { return }
  255. currentItem = label
  256. currentLabel.font = option.font
  257. currentLabel.textColor = option.normalColor
  258. label.textColor = option.selectedColor
  259. label.font = UIFont.systemFont(ofSize: option.font.pointSize + 1)
  260. currentIndex = index
  261. updateSliderConstraint()
  262. }
  263. func sliderAnimation(_ index: Int) {
  264. let isLeft = currentIndex - index > 0
  265. var animationDistance: CGFloat = 0
  266. for i in isLeft ? (index..<currentIndex) : (currentIndex..<index) {
  267. animationDistance += menuItemWidths[i] / 2 + menuItemWidths[i + 1] / 2 + option.spacing
  268. }
  269. UIView.animate(withDuration: 0.25) {
  270. self.sliderConstraint?.constant = isLeft ? -animationDistance : animationDistance
  271. self.menuView.layoutIfNeeded()
  272. }
  273. }
  274. func updateSliderConstraint() {
  275. NSLayoutConstraint.deactivate([sliderConstraint!])
  276. sliderConstraint = sliderView.centerXAnchor.constraint(equalTo: currentItem!.centerXAnchor)
  277. NSLayoutConstraint.activate([sliderConstraint!])
  278. }
  279. }
  280. /// page linkage
  281. fileprivate extension PageViewController {
  282. func didSelectPageItem(_ index: Int) {
  283. scrollView.setContentOffset(CGPoint.init(x: CGFloat(index) * contentRect.width, y: 0), animated: true)
  284. }
  285. func pageViewDidEndScroll() {
  286. guard self.scrollView.contentOffset.x != startOffset else { return }
  287. let index = Int(self.scrollView.contentOffset.x / contentRect.width)
  288. pageItems[index].viewController.didMove(toParent: self)
  289. switch direction {
  290. case .left:
  291. didSelectMenuItem(index)
  292. case .right:
  293. didSelectMenuItem(index)
  294. }
  295. }
  296. }