How to use BehaviorRelay as an alternate to Variable in RxSwift?

Question

As of RxSwift4, Variable is moved to Deprecated.swift marking the possible deprecation of Variable in future. An alternate proposed to

Answer 1

Building on Dalton's answer, here is a handy extension:

extension BehaviorRelay where Element: RangeReplaceableCollection {
    func acceptAppending(_ element: Element.Element) {
        accept(value + [element])
    }
}

Answer 2

I wrote this extension for replacing Variables with BehaviorRelays. You can add whatever method you need based on this pattern to migrate easily.

public extension BehaviorRelay where Element: RangeReplaceableCollection {

    public func insert(_ subElement: Element.Element, at index: Element.Index) {
        var newValue = value
        newValue.insert(subElement, at: index)
        accept(newValue)
    }

    public func insert(contentsOf newSubelements: Element, at index: Element.Index) {
        var newValue = value
        newValue.insert(contentsOf: newSubelements, at: index)
        accept(newValue)
    }

    public func remove(at index: Element.Index) {
        var newValue = value
        newValue.remove(at: index)
        accept(newValue)
    }
}

Instead of Variable.value.funcName, now you write BehaviorRelay.funcName.

The idea to use where Element: RangeReplaceableCollection clause comes from retendo's answer

Also note that the index is of type Element.Index, not Int or whatever else.