wanewang/observablearray-rxswift

An array that can emit messages of elements and diffs on it's changing.

ObservableArray-RxSwift

ObservableArray is an array that can emit messages of elements and diffs when it is mutated.

Usage

ObservableArray has two Observables:

func rx_elements() -> Observable<[Element]>
func rx_events() -> Observable<ArrayChangeEvent>

rx_elements

rx_elements() emits own elements when mutated.

var array: ObservableArray<String> = ["foo", "bar", "buzz"]
array.rx_elements().subscribeNext { print($0) }

array.append("coffee")
array[2] = "milk"
array.removeAll()

This will print:

["foo", "bar", "buzz"]
["foo", "bar", "buzz", "coffee"]
["foo", "bar", "milk", "coffee"]
[]

Please note that rx_elements() emits the current items first when it has subscribed because it is implemented by using BehaviorSubject.

rx_elements can work with rx_itemsWithCellIdentifier:

model.rx_elements()
    .observeOn(MainScheduler.instance)
    .bindTo(tableView.rx_itemsWithCellIdentifier("MySampleCell")) { (row, element, cell) in
        guard let c = cell as? MySampleCell else { return }
        c.model = self.model[row]
        return
    }
    .addDisposableTo(disposeBag)

rx_events

rx_events() emits ArrayChangeEvent that contains indices of diffs when mutated.

var array: ObservableArray<String> = ["foo", "bar", "buzz"]
array.rx_events().subscribeNext { print($0) }

array.append("coffee")
array[2] = "milk"
array.removeAll()

This will print:

ArrayChangeEvent(insertedIndices: [3], deletedIndices: [], updatedIndices: [])
ArrayChangeEvent(insertedIndices: [], deletedIndices: [], updatedIndices: [2])
ArrayChangeEvent(insertedIndices: [], deletedIndices: [0, 1, 2, 3], updatedIndices: [])

ArrayChangeEvent is defined as:

struct ArrayChangeEvent {
    let insertedIndices: [Int]
    let deletedIndices: [Int]
    let updatedIndices: [Int]
}

These indices can be used with table view methods, such like insertRowsAtIndexPaths(_:withRowAnimation:). For example, the following code will enable cell animations when the source array is mutated.

extension UITableView {
    public func rx_autoUpdater(source: Observable<ArrayChangeEvent>) -> Disposable {
        return source
            .scan((0, nil)) { (a: (Int, ArrayChangeEvent!), ev) in
                return (a.0 + ev.insertedIndices.count - ev.deletedIndices.count, ev)
            }
            .observeOn(MainScheduler.instance)
            .subscribeNext { sourceCount, event in
                guard let event = event else { return }

                let tableCount = self.numberOfRowsInSection(0)
                guard tableCount + event.insertedIndices.count - event.deletedIndices.count == sourceCount else {
                    self.reloadData()
                    return
                }

                func toIndexSet(array: [Int]) -> [NSIndexPath] {
                    return array.map { NSIndexPath(forRow: $0, inSection: 0) }
                }

                self.beginUpdates()
                self.insertRowsAtIndexPaths(toIndexSet(event.insertedIndices), withRowAnimation: .Automatic)
                self.deleteRowsAtIndexPaths(toIndexSet(event.deletedIndices), withRowAnimation: .Automatic)
                self.reloadRowsAtIndexPaths(toIndexSet(event.updatedIndices), withRowAnimation: .Automatic)
                self.endUpdates()
            }
    }
}

You can use rx_autoUpdater(_:) with bindTo(_:) in your view contollers:

model.rx_events()
    .observeOn(MainScheduler.instance)
    .bindTo(tableView.rx_autoUpdater)
    .addDisposableTo(disposeBag)

Unfortunately, rx_autoUpdater doesn't work with rx_elements() binding to rx_itemsWithCellIdentifier(_:source:configureCell:cellType:), because it uses reloadData() internally.

Supported Methods

ObservableArray implements the following methods and properties, which work the same way as Array's equivalent methods. You can also use additional Array methods defined in protocol extensions, such as sort, reverse and enumerate.

init()
init(count:Int, repeatedValue: Element)
init<S : SequenceType where S.Generator.Element == Element>(_ s: S)
init(arrayLiteral elements: Element...)

var startIndex: Int
var endIndex: Int
var capacity: Int

func reserveCapacity(minimumCapacity: Int)
func append(newElement: Element)
func appendContentsOf<S : SequenceType where S.Generator.Element == Element>(newElements: S)
func appendContentsOf<C : CollectionType where C.Generator.Element == Element>(newElements: C)
func removeLast() -> Element
func insert(newElement: Element, atIndex i: Int)
func removeAtIndex(index: Int) -> Element
func removeAll(keepCapacity: Bool = false)
func insertContentsOf(newElements: [Element], atIndex i: Int)
func replaceRange<C : CollectionType where C.Generator.Element == Element>(subRange: Range<Int>, with newCollection: C)
func popLast() -> Element?

var description: String
var debugDescription: String

subscript(index: Int) -> Element
subscript(bounds: Range<Int>) -> ArraySlice<Element>

Install

CocoaPods

pod 'ObservableArray-RxSwift'

Important: Use the following import statement to import ObservableArray-RxSwift:

import ObservableArray_RxSwift

Carthage

github "safx/ObservableArray-RxSwift"

Manual Install

Just copy ObservableArray.swift into your project.

License

MIT