NSBarcelona - Making UITableView great again

None of us thought that tableview layouts coud fun or easy. After we sat down and solved the issues once and for all, we changed our minds. In this talk we are going tell you all how we did it.

Transcript

1. Making UITableView great again Alfredo Delli Bovi
 @adellibovi
2. Agenda • Where we began with UITableView • What went wrong • Fixing it •
3. UITableView evolution iOS 2.0 Registering Nibs Registering Classes Custom Headers and Footer iOS 5.0 iOS 6.0
4. Introduction of estimated height iOS 7 .0 iOS 10.0 Prefetching Self sizing cells iOS 8.0
5. TableView is fast 0ms 200ms 400ms 600ms 800ms Cells count 0 20 40 60 80 100 UIStackView UICollectionViewFlowLayout + Auto Layout UICollectionViewFlowLayout + Manual Layout UITableView + Manual Layout UITableView + Auto Layout http://layoutkit.org/benchmarks/
6. Is there anything wrong with UITableView?
7. Is there anything wrong with UITableView? No
8. –Uncle Ben “With great power comes great responsibility.”
9. static let identifier = “CellIdentifier" override func viewDidLoad() { super.viewDidLoad() self.tableView.register(Cell.self, forCellReuseIdentifier: identifier) } func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int { return array.count } func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { let cell = tableView.dequeueReusableCell(withIdentifier: identifier, for: indexPath) // Configure the cell... return cell } func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) { // Do some action }
10. static let identifier = “CellIdentifier" override func viewDidLoad() { super.viewDidLoad() self.tableView.register(Cell.self, forCellReuseIdentifier: identifier) } func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int { return array.count } func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { let cell = tableView.dequeueReusableCell(withIdentifier: identifier, for: indexPath) // Configure the cell... return cell } func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) { // Do some action }
11. static let identifier = “CellIdentifier" override func viewDidLoad() { super.viewDidLoad() self.tableView.register(Cell.self, forCellReuseIdentifier: identifier) } func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int { return array.count } func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { let cell = tableView.dequeueReusableCell(withIdentifier: identifier, for: indexPath) // Configure the cell... return cell } func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) { // Do some action }
12. static let identifier = “CellIdentifier" override func viewDidLoad() { super.viewDidLoad() self.tableView.register(Cell.self, forCellReuseIdentifier: identifier) } func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int { return array.count } func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { let cell = tableView.dequeueReusableCell(withIdentifier: identifier, for: indexPath) // Configure the cell... return cell } func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) { // Do some action }
13. static let identifier = “CellIdentifier" override func viewDidLoad() { super.viewDidLoad() self.tableView.register(Cell.self, forCellReuseIdentifier: identifier) } func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int { return array.count } func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { let cell = tableView.dequeueReusableCell(withIdentifier: identifier, for: indexPath) // Configure the cell... return cell } func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) { // Do some action }
14. override func viewDidLoad() { super.viewDidLoad() self.tableView.register(Cell.self, forCellReuseIdentifier: "CellIdentifier") self.tableView.register(Cell2.self, forCellReuseIdentifier: "CellIdentifier2") } func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int { return array.count } func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { let cell: UITableViewCell if (shouldReturnTheFirstTypeOfCell) { cell = tableView.dequeueReusableCell(withIdentifier: "CellIdentifier", for: indexPath) // Configure the cell 1... } else { cell = tableView.dequeueReusableCell(withIdentifier: "CellIdentifier2", for: indexPath) // Configure the cell 2... } return cell } func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat { if (shouldReturnTheFirstTypeOfCell) { return 44.0 } else { return 120.0 } } func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) { // Do some action }
15. override func viewDidLoad() { super.viewDidLoad() self.tableView.register(Cell.self, forCellReuseIdentifier: "CellIdentifier") self.tableView.register(Cell2.self, forCellReuseIdentifier: "CellIdentifier2") } func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int { return array.count } func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { let cell: UITableViewCell if (shouldReturnTheFirstTypeOfCell) { cell = tableView.dequeueReusableCell(withIdentifier: "CellIdentifier", for: indexPath) // Configure the cell 1... } else { cell = tableView.dequeueReusableCell(withIdentifier: "CellIdentifier2", for: indexPath) // Configure the cell 2... } return cell } func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat { if (shouldReturnTheFirstTypeOfCell) { return 44.0 } else { return 120.0 } } func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) { // Do some action }
16. override func viewDidLoad() { super.viewDidLoad() self.tableView.register(Cell.self, forCellReuseIdentifier: "CellIdentifier") self.tableView.register(Cell2.self, forCellReuseIdentifier: “CellIdentifier2") self.tableView.register(Header.self, forHeaderFooterViewReuseIdentifier: “Header") self.tableView.register(Footer.self, forHeaderFooterViewReuseIdentifier: “Footer") } func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int { return array.count } func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { let cell: UITableViewCell if (shouldReturnTheFirstTypeOfCell) { cell = tableView.dequeueReusableCell(withIdentifier: "CellIdentifier", for: indexPath) // Configure the cell 1... } else { cell = tableView.dequeueReusableCell(withIdentifier: "CellIdentifier2", for: indexPath) // Configure the cell 2... } return cell } func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat { if (shouldReturnTheFirstTypeOfCell) { return 44.0 } else { return 120.0 } } func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) { // Do some action } func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? { return tableView.dequeueReusableHeaderFooterView(withIdentifier: “Header”) } func tableView(_ tableView: UITableView, viewForFooterInSection section: Int) -> UIView? { return tableView.dequeueReusableHeaderFooterView(withIdentifier: “Footer”) } func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat { return 20.0 } func tableView(_ tableView: UITableView, heightForFooterInSection section: Int) -> CGFloat { return 60.0 }
17. override func viewDidLoad() { super.viewDidLoad() self.tableView.register(Cell.self, forCellReuseIdentifier: "CellIdentifier") self.tableView.register(Cell2.self, forCellReuseIdentifier: “CellIdentifier2") self.tableView.register(Header.self, forHeaderFooterViewReuseIdentifier: “Header") self.tableView.register(Footer.self, forHeaderFooterViewReuseIdentifier: “Footer") } func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int { return array.count } func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { let cell: UITableViewCell if (shouldReturnTheFirstTypeOfCell) { cell = tableView.dequeueReusableCell(withIdentifier: "CellIdentifier", for: indexPath) // Configure the cell 1... } else { cell = tableView.dequeueReusableCell(withIdentifier: "CellIdentifier2", for: indexPath) // Configure the cell 2... } return cell } func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat { if (shouldReturnTheFirstTypeOfCell) { return 44.0 } else { return 120.0 } } func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) { // Do some action } func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? { return tableView.dequeueReusableHeaderFooterView(withIdentifier: “Header”) } func tableView(_ tableView: UITableView, viewForFooterInSection section: Int) -> UIView? { return tableView.dequeueReusableHeaderFooterView(withIdentifier: “Footer”) } func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat { return 20.0 } func tableView(_ tableView: UITableView, heightForFooterInSection section: Int) -> CGFloat { return 60.0 }
18. override func viewDidLoad() { super.viewDidLoad() self.tableView.register(Cell.self, forCellReuseIdentifier: "CellIdentifier") self.tableView.register(Cell2.self, forCellReuseIdentifier: “CellIdentifier2") self.tableView.register(Header.self, forHeaderFooterViewReuseIdentifier: “Header") self.tableView.register(Footer.self, forHeaderFooterViewReuseIdentifier: “Footer") } func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int { return array.count } func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { let cell: UITableViewCell if (shouldReturnTheFirstTypeOfCell) { cell = tableView.dequeueReusableCell(withIdentifier: "CellIdentifier", for: indexPath) // Configure the cell 1... } else { cell = tableView.dequeueReusableCell(withIdentifier: "CellIdentifier2", for: indexPath) // Configure the cell 2... } return cell } func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat { if (shouldReturnTheFirstTypeOfCell) { return 44.0 } else { return 120.0 } } func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) { // Do some action } func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? { return tableView.dequeueReusableHeaderFooterView(withIdentifier: “Header”) } func tableView(_ tableView: UITableView, viewForFooterInSection section: Int) -> UIView? { return tableView.dequeueReusableHeaderFooterView(withIdentifier: “Footer”) } func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat { return 20.0 } func tableView(_ tableView: UITableView, heightForFooterInSection section: Int) -> CGFloat { return 60.0 }
19. override func viewDidLoad() { super.viewDidLoad() self.tableView.register(Cell.self, forCellReuseIdentifier: "CellIdentifier") self.tableView.register(Cell2.self, forCellReuseIdentifier: “CellIdentifier2") self.tableView.register(Header.self, forHeaderFooterViewReuseIdentifier: “Header") self.tableView.register(Footer.self, forHeaderFooterViewReuseIdentifier: “Footer") } func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int { return array.count } func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { let cell: UITableViewCell if (shouldReturnTheFirstTypeOfCell) { cell = tableView.dequeueReusableCell(withIdentifier: "CellIdentifier", for: indexPath) // Configure the cell 1... } else { cell = tableView.dequeueReusableCell(withIdentifier: "CellIdentifier2", for: indexPath) // Configure the cell 2... } return cell } func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat { if (shouldReturnTheFirstTypeOfCell) { return 44.0 } else { return 120.0 } } func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) { // Do some action } func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? { return tableView.dequeueReusableHeaderFooterView(withIdentifier: “Header”) } func tableView(_ tableView: UITableView, viewForFooterInSection section: Int) -> UIView? { return tableView.dequeueReusableHeaderFooterView(withIdentifier: “Footer”) } func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat { return 20.0 } func tableView(_ tableView: UITableView, heightForFooterInSection section: Int) -> CGFloat { return 60.0 }
20. override func viewDidLoad() { super.viewDidLoad() self.tableView.register(Cell.self, forCellReuseIdentifier: "CellIdentifier") self.tableView.register(Cell2.self, forCellReuseIdentifier: “CellIdentifier2") self.tableView.register(Header.self, forHeaderFooterViewReuseIdentifier: “Header") self.tableView.register(Footer.self, forHeaderFooterViewReuseIdentifier: “Footer") } func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int { return array.count } func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { let cell: UITableViewCell if (shouldReturnTheFirstTypeOfCell) { cell = tableView.dequeueReusableCell(withIdentifier: "CellIdentifier", for: indexPath) // Configure the cell 1... } else { cell = tableView.dequeueReusableCell(withIdentifier: "CellIdentifier2", for: indexPath) // Configure the cell 2... } return cell } func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat { if (shouldReturnTheFirstTypeOfCell) { return 44.0 } else { return 120.0 } } func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) { // Do some action } func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? { return tableView.dequeueReusableHeaderFooterView(withIdentifier: “Header”) } func tableView(_ tableView: UITableView, viewForFooterInSection section: Int) -> UIView? { return tableView.dequeueReusableHeaderFooterView(withIdentifier: “Footer”) } func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat { return 20.0 } func tableView(_ tableView: UITableView, heightForFooterInSection section: Int) -> CGFloat { return 60.0 }
21. override func viewDidLoad() { super.viewDidLoad() self.tableView.register(Cell.self, forCellReuseIdentifier: "CellIdentifier") self.tableView.register(Cell2.self, forCellReuseIdentifier: “CellIdentifier2") self.tableView.register(Header.self, forHeaderFooterViewReuseIdentifier: “Header") self.tableView.register(Footer.self, forHeaderFooterViewReuseIdentifier: “Footer") } func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int { return array.count } func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { let cell: UITableViewCell if (shouldReturnTheFirstTypeOfCell) { cell = tableView.dequeueReusableCell(withIdentifier: "CellIdentifier", for: indexPath) // Configure the cell 1... } else { cell = tableView.dequeueReusableCell(withIdentifier: "CellIdentifier2", for: indexPath) // Configure the cell 2... } return cell } func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat { if (shouldReturnTheFirstTypeOfCell) { return 44.0 } else { return 120.0 } } func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) { // Do some action } func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? { return tableView.dequeueReusableHeaderFooterView(withIdentifier: “Header”) } func tableView(_ tableView: UITableView, viewForFooterInSection section: Int) -> UIView? { return tableView.dequeueReusableHeaderFooterView(withIdentifier: “Footer”) } func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat { return 20.0 } func tableView(_ tableView: UITableView, heightForFooterInSection section: Int) -> CGFloat { return 60.0 }
22. public func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? public func tableView(_ tableView: UITableView, viewForFooterInSection section: Int) -> UIView? public func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int public func numberOfSections(in tableView: UITableView) -> Int public func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell public func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat public func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat public func tableView(_ tableView: UITableView, heightForFooterInSection section: Int) -> CGFloat public func tableView(_ tableView: UITableView, estimatedHeightForRowAt indexPath: IndexPath) -> CGFloat public func tableView(_ tableView: UITableView, estimatedHeightForHeaderInSection section: Int) -> CGFloat public func tableView(_ tableView: UITableView, estimatedHeightForFooterInSection section: Int) -> CGFloat Those are 11 methods!
23. Folded Unfolded
25. func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
 switch row {
 case 0:
 return firstCell
 case 1...array.count:
 return dataCell
 case array.count+1 where folded == false:
 return showMoreCell
 case array.count+2,
 array.count+1 where folded == true:
 return specialCell
 default: nil!
 }

26. func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
 switch row {
 case 0:
 return firstCell
 case 1...array.count:
 return dataCell
 case array.count+1 where folded == false:
 return showMoreCell
 case array.count+2,
 array.count+1 where folded == true:
 return specialCell
 default: nil!
 }
 func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
 return array.count + (folded ? 2 : 3)
 }

27. func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
 switch row {
 case 0:
 return firstCell
 case 1...array.count:
 return dataCell
 case array.count+1 where folded == false:
 return showMoreCell
 case array.count+2,
 array.count+1 where folded == true:
 return specialCell
 default: nil!
 }
 func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
 return array.count + (folded ? 2 : 3)
 }
 if (folded) {
 tableView.deleteRows(at: [IndexPath(row: array.count + 1, section: 0)], with: .fade)
 } else {
 tableView.insertRows(at: [IndexPath(row: array.count + 1, section: 0)], with: .fade)
 }
28. UITableView.reloadData()
29. open class UITableView : UIScrollView, NSCoding { public func reloadData(){ self.stopsLoving(you) } }
30. Boilerplate Complex layout are hard Small change = Rewrite code + No reusability Manual insertions or reloadData
32. Calculate the height Drawing the cell Number of sections Number of rows in a section Managing states Registering cells Registering Headers Drawing header Interaction
33. Delegate Calculate the height Drawing the cell Number of sections Number of rows in a section Managing states Registering cells Registering Headers Drawing header Interaction
34. Calculate the height Drawing the cell Number of sections Number of rows in a section Managing states Registering cells Registering Headers Drawing header Interaction
35. Separation of Concerns
36. Delegate
37. TableViewManager
38. TableViewManager Section Section Section
39. TableViewManager Section Section Section Item Item Item Header Footer
40. TableViewManager Section Section Section Drawer Drawer Drawer Item Item Item Header Footer
41. TableViewManager Section Section Section Drawer Drawer Drawer Item Item Item Header Footer UITableHeaderFooterView UITableViewCell UITableHeaderFooterView
42. Create all the protocols!
43. protocol TableViewManager: UITableViewDelegate, UITableViewDataSource {
 var sections: [Section] { get set }
 }

44. protocol TableViewManager: UITableViewDelegate, UITableViewDataSource {
 var sections: [Section] { get set }
 }
 protocol Section {
 var items: [Item] { get set }
 var header: HeaderFooter? { get }
 var footer: HeaderFooter? { get }
 }

45. protocol TableViewManager: UITableViewDelegate, UITableViewDataSource {
 var sections: [Section] { get set }
 }
 protocol Section {
 var items: [Item] { get set }
 var header: HeaderFooter? { get }
 var footer: HeaderFooter? { get }
 }
 protocol Item {
 var drawer: CellDrawer.Type { get }
 var height: Height? { get }
 }

46. protocol TableViewManager: UITableViewDelegate, UITableViewDataSource {
 var sections: [Section] { get set }
 }
 protocol Section {
 var items: [Item] { get set }
 var header: HeaderFooter? { get }
 var footer: HeaderFooter? { get }
 }
 protocol Item {
 var drawer: CellDrawer.Type { get }
 var height: Height? { get }
 }
 protocol HeaderFooter {
 var drawer: HeaderFooterDrawer.Type { get }
 var height: Height? { get }
 }
47. protocol Item {
 var drawer: CellDrawer.Type { get }
 var height: Height? { get }
 }
48. protocol CellDrawer { }
49. protocol CellDrawer { } static var type: CellType { get }

50. protocol CellDrawer { } static var type: CellType { get }
 typealias CellType = NibClassType<UITableViewCell> enum NibClassType<T> { case nib(UINib, T.Type) case `class`(T.Type) }
51. protocol CellDrawer { } static var type: CellType { get }
 static func draw(_ cell: UITableViewCell, with item: Item)

52. protocol CellDrawer { } static var type: CellType { get }
 static func draw(_ cell: UITableViewCell, with item: Item)
 static func cell(in tableView: UITableView, with item: Item, for indexPath: IndexPath) -> UITableViewCell
53. extension CellDrawer {
 static func cell(in manager: TableViewManager, with item: Item, for indexPath: IndexPath) -> UITableViewCell { let cell = manager.tableView.dequeueReusableCell(withIdentifier: self.type.reusableIdentifier, for: indexPath) return cell
 }
 }
54. extension CellDrawer {
 static func cell(in manager: TableViewManager, with item: Item, for indexPath: IndexPath) -> UITableViewCell { let cell = manager.tableView.dequeueReusableCell(withIdentifier: self.type.reusableIdentifier, for: indexPath) return cell
 }
 } extension NibClassType {
 var reusableIdentifier: String {
 switch self { case .class(let cellClass): return String(describing: cellClass) case .nib(_, let cellClass): return String(describing: cellClass) } } }
55. protocol Item {
 var drawer: CellDrawer.Type { get }
 var height: Height? { get }
 }
56. enum Height { case dynamic(CGFloat) case `static`(CGFloat) }
57. enum Height { case dynamic(CGFloat) case `static`(CGFloat)
 } extension Height { var estimated: CGFloat { switch self { case .static(let value): return value case .dynamic(let value): return value } } var height: CGFloat { switch self { case .static(let value): return value case .dynamic(_): return UITableViewAutomaticDimension } } }
58. public func tableView(_ tableView: UITableView, viewForHeaderInSection section: Int) -> UIView? public func tableView(_ tableView: UITableView, viewForFooterInSection section: Int) -> UIView? public func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int public func numberOfSections(in tableView: UITableView) -> Int public func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell public func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat public func tableView(_ tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat public func tableView(_ tableView: UITableView, heightForFooterInSection section: Int) -> CGFloat public func tableView(_ tableView: UITableView, estimatedHeightForRowAt indexPath: IndexPath) -> CGFloat public func tableView(_ tableView: UITableView, estimatedHeightForHeaderInSection section: Int) -> CGFloat public func tableView(_ tableView: UITableView, estimatedHeightForFooterInSection section: Int) -> CGFloat
59. *** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'unable to dequeue a cell with identifier UITableViewCell - must register a nib or a class for the identifier or connect a prototype cell in a storyboard' *** First throw call stack: ( 0 CoreFoundation 0x0000000108666d4b __exceptionPreprocess + 171 1 libobjc.A.dylib 0x00000001058af21e objc_exception_throw + 48 2 CoreFoundation 0x000000010866ae42 +[NSException raise:format:arguments:] + 98 3 Foundation 0x000000010544471d -[NSAssertionHandler handleFailureInMethod:object:file:lineNumber:description:] + 195 4 UIKit 0x00000001065eb8f4 -[UITableView dequeueReusableCellWithIdentifier:forIndexPath:] + 259
60. extension UITableView {
 func register(_ type: NibClassType<UITableViewCell>) {
 switch type {
 case .class(let class):
 register(class, forCellReuseIdentifier: type.reusableIdentifier)
 case .nib(let nib, _):
 register(nib, forCellReuseIdentifier: type.reusableIdentifier)
 }
 }
 }

61. extension UITableView {
 func register(_ type: NibClassType<UITableViewCell>) {
 switch type {
 case .class(let class):
 register(class, forCellReuseIdentifier: type.reusableIdentifier)
 case .nib(let nib, _):
 register(nib, forCellReuseIdentifier: type.reusableIdentifier)
 }
 }
 }
 extension Section {
 func register(in manager: TableViewManager) {
 if case .view(let header) = header {
 manager.tableView.register(header.drawer.type)
 }
 if case .view(let footer) = footer {
 manager.tableView.register(footer.drawer.type)
 }
 items.forEach {
 manager.tableView.register($0.drawer.type)
 }
 }
 }

62. extension UITableView {
 func register(_ type: NibClassType<UITableViewCell>) {
 switch type {
 case .class(let class):
 register(class, forCellReuseIdentifier: type.reusableIdentifier)
 case .nib(let nib, _):
 register(nib, forCellReuseIdentifier: type.reusableIdentifier)
 }
 }
 }
 extension Section {
 func register(in manager: TableViewManager) {
 if case .view(let header) = header {
 manager.tableView.register(header.drawer.type)
 }
 if case .view(let footer) = footer {
 manager.tableView.register(footer.drawer.type)
 }
 items.forEach {
 manager.tableView.register($0.drawer.type)
 }
 }
 }
 sections.forEach { $0.register(in: self) }
63. A B
64. A B .beginUpdates
65. A B .moves([0,4])
66. A B .deletes([3])
67. A B .inserts([2,3])
68. A B .endUpdates
69. Longest Common Subsequence
70. enum ArrayChanges {
 case inserts([Int])
 case deletes([Int])
 case moves([(Int, Int)])
 case beginUpdates
 case endUpdates
 }
 Longest Common Subsequence
71. enum ArrayChanges {
 case inserts([Int])
 case deletes([Int])
 case moves([(Int, Int)])
 case beginUpdates
 case endUpdates
 }
 extension MutableCollection {
 mutating func replace(with array: [Element]) { }
 } Longest Common Subsequence
72. protocol Stateful: Section { associatedtype State var currentState: State { get set } 
 func items(for state: State) -> [Item] func transition(to newState: State)
 }

73. protocol Stateful: Section { associatedtype State var currentState: State { get set } 
 func items(for state: State) -> [Item] func transition(to newState: State)
 }

74. protocol Stateful: Section { associatedtype State var currentState: State { get set } 
 func items(for state: State) -> [Item] func transition(to newState: State)
 }

75. protocol Stateful: Section { associatedtype State var currentState: State { get set } 
 func items(for state: State) -> [Item] func transition(to newState: State)
 }

76. protocol Stateful: Section { associatedtype State var currentState: State { get set } 
 func items(for state: State) -> [Item] func transition(to newState: State)
 }
 extension Stateful {
 func transition(to newState: State) {
 items.replace(with: items(for: newState))
 currentState = newState
 }
 }
77. class OurSection: Section, Stateful {
 var currentState: State

78. class OurSection: Section, Stateful {
 var currentState: State
 enum State {
 case folded, unfolded
 }

79. class OurSection: Section, Stateful {
 var currentState: State
 enum State {
 case folded, unfolded
 }
 func items(for state: State) -> [Item]
 switch state {
 case .folded:
 return [FirstItem(), DataItem(), ShowMoreItem()] 
 case .unfolded:
 return [FirstItem(), DataItem(), SpecialItem(), ShowMoreItem()]
 }
 }
 }
80. class OurSection: Section, Stateful {
 var currentState: State
 
 enum State {
 case folded, unfolded
 }
 func items(for state: State) -> [Item]
 switch state {
 
 
 
 
 }
 }
 } case .folded:
 return [FirstItem(), DataItem(), ShowMoreItem()] 
 case .unfolded:
 return [FirstItem(), DataItem(), SpecialItem(), ShowMoreItem()]
81. class OurSection: Section, Stateful {
 var currentState: State
 
 enum State {
 case folded, unfolded
 }
 func items(for state: State) -> [Item]
 switch state {
 
 
 
 
 }
 }
 } case .folded: return [ShowMoreItem(), FirstItem(), DataItem()] case .unfolded: return [ShowMoreItem(), SpecialItem() FirstItem(), DataItem()]
82. Boilerplate Complex layout are hard Small change = Rewrite code + No reusability Manual insertions or reloadData
83. Boilerplate Complex layout are hard Small change = Rewrite code + No reusability Manual insertions or reloadData
84. No more delegate Complex layout are hard Small change = Rewrite code + No reusability Manual insertions or reloadData
85. No more delegate ☀ Complex layout are easy Small change = Rewrite code + No reusability Manual insertions or reloadData
86. No more delegate ☀ Complex layout are easy Change everything with few lines + No reusability Manual insertions or reloadData
87. No more delegate ☀ Complex layout are easy Change everything with few lines 1 Items, sections, headers Manual insertions or reloadData
88. No more delegate ☀ Complex layout are easy Change everything with few lines 1 Items, sections, headers ❤ Automatic diffs and animations
89. No more delegate ☀ Complex layout are easy Change everything with few lines 1 Items, sections, headers ❤ Automatic diffs and animations
90. One more thing…
92. github.com/odigeoteam/TableViewKit Empowering UITableView with painless multi-type cell support and build-in automatic state transition animations
93. May be with you