主要架构

流程由四个不同的实体组成：

• TableManager：唯一负责管理UITableView实例内容的表管理器。
• Section：代表表格中的一个节。它管理行的列表以及可选的头和尾。
• Row：代表节中的一个行；行链接到一对对象：模型（任何类；如不适用，则有效的Void）和细胞（符合DeclarativeCell协议的UITableViewCell子类）。
• SectionView：一个节可能显示头/尾；这些对象可能是简单的String或自定义视图：SectionView。正如Row一样，SectionView与模型和视图（UITableViewHeaderFooterView的子类）相关联。

示例应用

Create the TableManager

In order to use Flow you must set the ownership of a UITableView instance to an instance of TableManager:

self.tableManager = TableManager(table: self.table!)

From now the UITableView instance is backed by Flow; every change (add/remove/move rows or sections) must be done by calling appropriate methods of the TableManager itself or any child Section/Row.

Prepare a Cell (for Row)

A row is resposible to manage the model and its graphical representation (the cell instance).
To create a new Row instance you need to specify the model class received by the instance cell and the cell class to instantiate into the table.

While sometimes a model is not applicable (your cell maybe a simple static representation or its decorative), the cell class is mandatory.
The cell must be a subclass of UITableViewCell conforms to DeclarativeCell protocol.
This protocol defines at least two important properties:

• the model assocated with the Cell (public typealias T = MyClass)
• a method called right after the row’s cell is dequeued (public func configure(_: T, path: IndexPath))

This is an example of a PlayerCell which is responsible to display data for a single football player (class PlayerModel):

import UIKit import Flow public class PlayerCell: UITableViewCell, DeclarativeCell { // assign to the cell the model to be represented  public typealias T = PlayerModel // if your cell has a fixed height you can set it directly at class level as below  public static var defaultHeight: CGFloat? = 157.0 // this func is called when a new instance of the cell is dequeued  // and you need to fill the data with a model instance.  public func configure(_ player: PlayerMode, path: IndexPath) { self.playerName.text = player.firstName self.playerLast.text = player.lastName self.playerImage.setURL(player.avatarURL) // ... and so on  } }

If your cell does not need of a model you can assign public typealias T = Void.

User interface of the cell can be made in two ways:

• Prototype (only in Storyboards): create a new prototype cell, assign the class to your class (here PlayerCell) and set the reuseIdentifier in IB to the same name of the class (again PlayerCell). By default Flow uses as identifier of the cell the same name of the class itself (you can change it by overriding reuseIdentifier static property).
• External XIB File: create a new xib file with the same name of your cell class (here PlayerCell.xib) and drag an instance of UITableViewCell class as the only single top level object. Assign to it the name of your class and the reuseIdentifier.

Height of a cell can be set in differen ways:

• If cell has a fixed height you can set it at class level by adding public static var defaultHeight: CGFloat? = ... in your cell subclass.
• If cell is autosized you can evaluate the height in row configuration (see below) by providing a value into estimatedHeight or evaluateEstimatedHeight() function.

Prepare a Row

You can now create a new row to add into the table; a Row instance is created by passing the DeclarativeCell type and an instance of the model represented.

let ronaldo = PlayerModel("Christiano","Ronaldo",.forward) ... let row_ronaldo = Row<PlayerCell>(model: ronaldo, { row in // ... configuration })

If model is not applicable just pass Void() as model param.

Inside the callback you can configure the various aspect of the row behaviour and appearance.
All standard UITableView events can be overriden; a common event is onDequeue, called when Row‘s linked cell instance is dequeued and displayed. Anoter one (onTap) allows you to perform an action on cell’s tap event.
So, for example:

let row_ronaldo = Row<PlayerCell>(model: ronaldo, { row in row.onDequeue = { _ in row.cell?.fullNameLabel.text = ronaldo.fullName return nil // when nil is returned cell will be deselected automatically  } row.onTap = { _ in print("Tapped cell") } })

There are lots of other events you can set into the row configuration callback (onDelete,onSelect,onDeselect,onShouldHighlit and so on).

Prepare Rows for an array of model

When you have an array of model instances to represent, one for each Row, you can use create shortcut.
The following code create an array of Rows<PlayerCell> where each row receive the relative item from self.players array.

let players_rows = Row<PlayerCell>.create(self.players)

Add Rows into the table

Adding rows to a table is easy as call a simple add function.

self.tableManager.add(rows: players_rows) // add rows (by appending a new section) self.tableManager.reloadData() // apply changes

(Remember: when you add rows without specifing a section a new section is created automatically for you).

Please note: when you apply a change to a table (by using add, remove or move functions, both for Section or Row instances) you must call the reloadData() function in order to reflect changes in UI.

If you want to apply changes using standard table’s animations just call update() function; it allows you to specify a list of actions to perform. In this case reloadData() is called automatically for you and the engine evaluate what’s changed automatically (inserted/moved/removed rows/section).

The following example add a new section at the end of the table and remove the first:

self.tableManager?.update(animation: .automatic, { self.tableManager?.insert(section: profileDetailSection, at: profileSection!.index! + 1) self.tableManager?.remove(sectionAt: 0) })

Create Section and manage header/footer

If not specified sections are created automatically when you add rows into a table.
Section objects encapulate the following properties:

• rows list of rows (RowProtocol) inside the section
• headerTitle / headerView a plain header string or a custom header view (SectionView)
• footerTitle / footerView a plain footer string or a custom footer view (SectionView)

Creating a new section with rows is pretty simple:

let rowPlayers: [RowProtocol] = ... let sectionPlayers = Section(id: SECTION_ID_PLAYERS, row: rowPlayers, headerTitle: "\(rowPlayers.count) PLAYERS")"

As like for Row even Section may have custom view for header or footer; in this case your custom header/footer must be an UITableViewHeaderFooterView subclass defined in a separate XIB file (with the same name of the class) which is conform to DeclarativeView protocol.
DeclarativeView protocol defines the model accepted by the custom view (as for Row you can use Void if not applicable).

For example:

import UIKit import Flow public class TeamSectionView: UITableViewHeaderFooterView, DeclarativeView { public typealias T = TeamModel // the model represented by the view, use `Void` if not applicable  public static var defaultHeight: CGFloat? = 100 public func configure(_ item: TeamModel, type: SectionType, section: Int) { self.sectionLabel?.text = item.name.uppercased() } }

Now you can create custom view as header for section:

let realMadridSection = Section(teamPlayers, headerView: SectionView<TeamSectionView>(team)) self.tableManager.add(section: realMadridSection) self.tableManager.reloadData()

UITableView animations

Flow fully supports animation for UITableView changes. As like for UICollectionView you will need to call a func which encapsulate the operations you want to apply.

In Flow it’s called update(animation: UITableViewRowAnimation, block: ((Void) -> (Void))).

Inside the block you can alter the sections of the table, remove or add rows and section or move things into other locations. At the end of the block Flow will take care to collect the animations needed to reflect applied changes both to the model and the UI and execute them.

You just need to remember only two things:

• Deletes are processed before inserts in batch operations. This means the indexes for the deletions are processed relative to the indexes of the collection view’s state before the batch operation, and the indexes for the insertions are processed relative to the indexes of the state after all the deletions in the batch operation.
• In order to make a correct refresh of the data, insertion must be done in order of the row index.

For example:

self.tableManager?.update(animation: .automatic, { self.tableManager?.remove(sectionAt: 1) // remove section 1  self.tableManager?.add(row: newPlayer, in: self.tableManager?.section(atIndex: 0)) // add a new row in section 0 })

Observe Row/Cell Events

Flow allows you to encapsulate the logic of your UITableViewCell instances directly in your Row objects. You can listen for dequeue, tap, manage highlights or edit… pratically everything you can do with plain tables, but more confortably.

All events are available and fully described into the Row class.
In this example you will see how to respond to the tap:

// Respond to tap on player's cells let rows = Row<PlayerCell>.create(players, { row in row.onTap = { _,path in print("Tap on player at \(String(path.row)): '\(row.item.fullName)'") return nil } })

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