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https://github.com/babylonhealth/Bento

Swift library for building component-based interfaces on top of UITableView and UICollectionView 🍱
https://github.com/babylonhealth/Bento
declarative diff diffing ios ios-swift swift uitableview
Last synced: 22 days ago
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Swift library for building component-based interfaces on top of UITableView and UICollectionView 🍱
Host: GitHub
URL: https://github.com/babylonhealth/Bento
Owner: babylonhealth
License: mit
Created: 2018-01-24T10:47:12.000Z (almost 7 years ago)
Default Branch: develop
Last Pushed: 2020-09-01T11:53:19.000Z (over 4 years ago)
Last Synced: 2024-04-11T15:06:50.868Z (8 months ago)
Topics: declarative, diff, diffing, ios, ios-swift, swift, uitableview
Language: Swift
Homepage:
Size: 13.4 MB
Stars: 372
Watchers: 32
Forks: 11
Open Issues: 7
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project

README

        
# [Bento](https://en.wikipedia.org/wiki/Bento) 🍱 弁当

> #### is a single-portion take-out or home-packed meal common in Japanese cuisine. A traditional bento holds rice or noodles, fish or meat, with pickled and cooked vegetables, in a box.

**Bento** is a Swift library for building component-based interfaces on top of `UITableView`.

- **Declarative:**  provides a painless approach for building `UITableView` interfaces

- **Diffing:** reloads your UI with beautiful animations when your data changes

- **Component-based:**  Design reusable components and share your custom UI across multiple screens of your app

In our experience it makes UI-related code easier to build and maintain. Our aim is to make the UI a function of state (i.e: `UI = f(state)`), which makes `Bento` a perfect fit for Reactive Programming.

## Content 📋

- [Installation](#installation-)

- [What's it like?](#whats-it-like-)

- [How does it work?](#how-does-it-work-)

- [Componments & StyleSheets](#components--stylesheets-)

- [Examples](#examples-)

- [Additional documentation](#additional-documentation-)

- [Development installation](#development-installation-)

- [State of the project](#state-of-the-project-%EF%B8%8F)

- [Development Resources](#development-resources)

- [Contributing](#contributing-%EF%B8%8F)

### Installation 💾

* Cocoapods

```ruby

target 'MyApp' do

    pod 'Bento'

end

```

* Carthage

```

github "Babylonpartners/Bento"

```

### What's it like? 🧐

When building a `Box`, all you need to care about are `Sections`s and `Node`s.

```swift

let box = Box.empty

            |-+ Section(id: SectionId.user,header: EmptySpaceComponent(height: 24, color: .clear))

            |---+ Node(id: RowID.user, component: IconTitleDetailsComponent(icon: image, title: patient.name))

            |-+ Section(id: SectionId.consultantDate, header: EmptySpaceComponent(height: 24, color: .clear))

            |---+ Node(id: RowID.loading, component: LoadingIndicatorComponent(isLoading: true))

        tableView.render(box)

```

### How does it work? 🤔

### Setup

Bento automatically performs the data source and delegate setup upon the very first time `UITableView` or `UICollectionView` is asked to render a Bento `Box`.

In other words, for Bento to work, it cannot be overridden with your own data source and delegate. If you wish to respond to delegate messages which Bento does not support as a feature, you may consider supplying a custom adapter using `prepareForBoxRendering(_:)`.

| Collection View | Adapter Base Class | Required Protocol Conformances |

| ---- | ---- | ---- |

| `UITableView` | `TableViewAdapterBase` | `UITableViewDataSource` & `UITableViewDelegate` |

| `UICollectionView` | `CollectionViewAdapterBase` | `UITableViewDataSource` & `UITableViewDelegate` |

#### Box 📦

`Box ` is a fundamental component of the library, essentially a virtual representation of the `UITableView` content. It has two generic parameters - `SectionId` and `RowId` - which are unique identifiers for  `Section` and `Node`, used by the [diffing engine](https://github.com/RACCommunity/FlexibleDiff) to perform animated changes of the `UITableView` content. Box is just a container for an array of sections.

#### Sections and Nodes 🏗

`Section`s and `Node`s are building blocks of a `Box`:

- `Section` is an abstraction of `UITableView`'s section which defines whether a header or footer should be shown.

- `Node` is an abstraction of `UITableView`'s row which defines how the data is rendered.

```swift

struct Section {

    let id: SectionId

    let header: AnyRenderable?

    let footer: AnyRenderable?

    let rows: [Node]

}

public struct Node {

    let id: Identifier

    let component: AnyRenderable

}

```

#### Identity 🎫

Identity, one of the key concepts, is used by the diffing algorithm to perform changes.

 > For general business concerns, full inequality of two instances does not necessarily mean inequality in terms of identity — it just means the data being held has changed if the identity of both instances is the same.

 (More info [here](https://github.com/RACCommunity/FlexibleDiff).)

`SectionID` and `ItemID` define the identity of sections and their items, respectively.

#### Renderable 🖼

`Renderable` is similar to [React](https://github.com/facebook/react)'s [Component](https://reactjs.org/docs/react-component.html)s. It's an abstraction of the real `UITableViewCell` that is going to be displayed. The idea is to make it possible to create small independent components that can be reused across many parts of your app.

```swift

public protocol Renderable: class {

    associatedtype View: UIView

    func render(in view: View)

}

class IconTextComponent: Renderable {

    private let title: String

    private let image: UIImage

    init(image: UIImage,

         title: String) {

        self.image = image

        self.title = title

    }

    func render(in view: IconTextCell) {

        view.titleLabel.text = title

        view.iconView.image = image

    }

}

```

#### Bento's arithmetics 💡

There are several custom operators that provide syntax sugar to make it easier to build `Bento`s:

```swift

precedencegroup ComposingPrecedence {

    associativity: left

    higherThan: NodeConcatenationPrecedence

}

precedencegroup NodeConcatenationPrecedence {

    associativity: left

    higherThan: SectionConcatenationPrecedence

}

precedencegroup SectionConcatenationPrecedence {

    associativity: left

    higherThan: AdditionPrecedence

}

infix operator |-+: SectionConcatenationPrecedence

infix operator |-?: SectionConcatenationPrecedence

infix operator |---+: NodeConcatenationPrecedence

infix operator |---?: NodeConcatenationPrecedence

let bento = Box.empty

	|-+ Section(id: SectionID.first) // 2

	|---+ Node(id: RowID.someId, Component()) // 1

```

As you might have noticed:

* `|-+` has `SectionConcatenationPrecedence`;

* `|---+` has `NodeConcatenationPrecedence`

`NodeConcatenationPrecedence` is higher than `|-+ / SectionConcatenationPrecedence`, meaning Nodes will be computed first. 

The order of the expression above is:

1. `Section() |---+ Node()` => `Section`

2. `Box() |-+ Section()` => `Box`

#### Conditional operators ❓

In addition to the `|-+` and `|---+` concatenation operators, Bento has conditional concatenation operators:

* `|-?` for `Section`

* `|---?` for `Node`

They are used to provide a `Section` or `Node` in a closure for the `Bool` and `Optional` happy path, via the `.iff` and `.some` functions.

Here are some examples:

```swift

let box = Box.empty

    |-? .iff(aBoolCondition) {

        Section()  // <-- Section only added if `boolCondition` is `true`

    }

```

```swift

let box = Box.empty

    |-? anOptional.map { unwrappedOptional in  // <-- the value of anOptional unwrapped

        Section()  // <-- Section only added if `anOptional` is not `nil`

    }

```

`|---?` works in exactly the same way for `Node`.

### Components & StyleSheets 🎨

Bento includes set of generic components like ``Description`, `TextInput`, `EmptySpace` etc. Bento uses StyleSheets to style components.

StyleSheets are a way to define **how** particular view should be rendered. Component's job is to provide **what** should be displayed while StyleSheets provide a style **how** it's done. Fonts, colors, alignment should go into StyleSheet. 

StyleSheets support KeyPaths for easier composition.

```swift

let styleSheet = LabelStyleSheet()

    .compose(\.numberOfLines, 3)

    .compose(\.font, UIFont.preferredFont(forTextStyle: .body))

```

StyleSheets can be used with Bento's components. All you need to do is to use correct stylesheet:

```swift

return .empty

  |-+ Section(id: .first)

  |---+ Node(

         id: .componentId,

         component: Component.Description(

             text: "Text",

             styleSheet: Component.Description.StyleSheet()

                 .compose(\.text.font, UIFont.preferredFont(forTextStyle: .body))

         )

   )

```

### Example 😎

![](Resources/example3.gif) 

### Additional documentation 📙

- [Common use cases](./Documentation/common_usecases.md)

### Development Installation 🛠

If you want to clone the repo for contributing or for running the example app you will need to install its dependencies which are stored as git submodules:

```

git submodule update --init --recursive

```

Or, if you have Carthage installed, you can use it to do the same thing:

```		

carthage checkout

```

### State of the project 🤷‍♂️

Feature | Status

--- | ---

`UITableView` | ✅

`UICollectionView` | ✅

Carthage Support | ✅

Free functions as alternative to the operators | ❌

### Development Resources

- [Bento Component Contract](Bento/Diff/ComponentContract.md)

  Define requirements that must be complied by the components from Bento, and best practices for developing a custom component.

### Contributing ✍️

Contributions are very welcome and highly appreciated! ❤️ Here's how to do it:

- If you have any questions feel free to create an issue with a `question` label;

- If you have a feature request you can create an issue with a `Feature request` label;

- If you found a bug feel free to create an issue with a `bug` label or open a PR with a fix.

#### Image attributions

[Coffee](https://pixabay.com/en/coffee-beans-coffee-beans-caffeine-3457587/)

[Pomegranate fruit](https://pixabay.com/en/pomegranate-fruit-exotic-fruit-3383814/)

[Cherries](https://pixabay.com/en/cherries-sweet-cherries-fruit-red-3433775/)

[Strawberries](https://pixabay.com/en/strawberries-season-spring-fruit-3359755/)