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https://github.com/wddwycc/infinitekit

Declarative infinite data flow
https://github.com/wddwycc/infinitekit

infinite-scroll rxswift swift

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Declarative infinite data flow

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README 

        
![logo](https://raw.githubusercontent.com/wddwycc/InfiniteKit/master/misc/header-logo.png)



[![Version](https://img.shields.io/cocoapods/v/InfiniteKit.svg?style=flat)](https://cocoapods.org/pods/InfiniteKit)

[![License](https://img.shields.io/cocoapods/l/InfiniteKit.svg?style=flat)](https://cocoapods.org/pods/InfiniteKit)

[![Platform](https://img.shields.io/cocoapods/p/InfiniteKit.svg?style=flat)](https://cocoapods.org/pods/InfiniteKit)



## Features



- [x] Create `Infinite Scroll` in declarative style with much less code

- [x] All states related UI covered by the library by default

- [x] Fully customizable

- [x] Well tested using RxTest



## Why



In real world iOS applications, most data from server are displayed with `UITableView` and `UICollectionView`. To create a full-featured infinite scroll using server data, developers should consider implementing many things:



- `Loading view`: display when reload or first time load

- `Empty view`: display when server returns empty data

- `Error view`: display when network error occurs

- `Pull to refresh`

- `Pull to load more`



Most junior developers would build up the data flow repeatedly, which would eventually lead to code redundancy and duplicated test cases.  

In most cases, Infinite scroll can be abstracted into a common pattern.  

InfiniteKit exists to let developers use this pattern easily, create full-featured infinite scroll faster, and in declarative style.



Let's build up a infinite scroll to list github users using [Github Open API](https://developer.github.com/v3/users/#get-all-users):



Firstly, take a look the abstraction in InfiniteKit `InfiniteList`:



- `Cell` is subclass of `UITableViewCell`

- `DataPack` represents data package receieved from server

- `CellModel` should be extracted from `DataPack` and used to render cell



We declare necessary types:



```swift

typealias Cell = UITableViewCell

struct CellModel: Codable {

    let id: Int

    let login: String

}

typealias DataPack = (data: [CellModel], offset: Int)

typealias List = InfiniteList

```



Next we declare how we gonna fetch data and use them to render our cells, with only four closures:



- `List.InitFetch`

- `List.NextFetch`

- `List.DataExtractor`

- `List.CellDecorator`



`List.InitFetch` is alias of `() -> Single`, generates first data fetch.



```swift

let initFetch: List.InitFetch = {

    let url = "https://api.github.com/users"

    let req = genReq(url: url)

    return sendReq(req, decodeWith: [CellModel].self)

        .map { (data: $0, offset: $0.count) }

        .asSingle()

}

```



`List.NextFetch` is alias of `(DataPack) -> Single`, generates data fetch based on the last fetched result, return nil if no more data is available.



```swift

let nextFetch: List.NextFetch = { lastDataPack in

    let url = "https://api.github.com/users"

    let params = ["since": String(lastDataPack.offset)]

    let req = genReq(url: url, params: params)

    return sendReq(req, decodeWith: [CellModel].self)

        .map { (data: $0, offset: lastDataPack.offset + $0.count) }

        .asSingle()

}

```



`List.DataExtractor` is alias of `([DataPack]) -> [CellModel]`, to map data packs to cell models.



```swift

let dataExtractor: List.DataExtractor = { dataPacks in

    let flattened = dataPacks.map { $0.data }.flatMap { $0 }

    // remove duplicate & order asc by id

    return Array(Set(flattened)).sorted(by: { $0.id < $1.id })

}

```



`List.CellDecorator` is alias of `(Cell, CellModel) -> Void`, to update cells using model.



```swift

let cellDecorator: List.CellDecorator = { cell, model in

    cell.textLabel?.text = model.login

}

```



We now can use this config to create our `List`, which is subclass of `ViewController`:



```swift

let config = List.Config(

    initFetch: initFetch,

    nextFetch: nextFetch,

    dataExtractor: dataExtractor,

    cellDecorator: cellDecorator

)

let list = List(config: config)

```



The `List` now has default `Loading view`, `Empty view`, `Error view`, `Pull to refresh`, `Pull to load more`, and the core data flow is well tested already by the library.



You can customize the `List` by configure `List.Config`



```swift

config.refreshControl // UIRefreshControl

config.loadingView // UIView

config.emptyViewAndReloadTrigger // (UIView, ControlEvent<()>)

config.errorViewAndReloadTrigger // (UIView, ControlEvent<()>)

```



## Todo



- [x] InfiniteList

- [ ] InfiniteSectionList

- [ ] InfiniteCollection

- [ ] InfiniteSecitonCollection



## Example



To run the example project, clone the repo, and run `pod install` from the example directory first.



## Requirements



## Installation



InfiniteKit is available through [CocoaPods](https://cocoapods.org). To install

it, simply add the following line to your Podfile:



```ruby

pod 'InfiniteKit'

```



## Author



wddwycc, [email protected]



## License



InfiniteKit is available under the MIT license. See the LICENSE file for more info.