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