레퍼런스 : https://todaycode.tistory.com/12

• Recyclerview 의 최하단 스크롤을 감지하여, page 수를 증가, API 재호출한다

binding.mainRecycler.addOnScrollListener(object : RecyclerView.OnScrollListener(){
    override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
        super.onScrolled(recyclerView, dx, dy)

        if(!binding.mainRecycler.canScrollVertically(1)){
            getIssueList(parentViewModel.getIssuePage())
        }
    }
})

• 재호출해서 수신한 추가 페이지 데이터를, 기존 데이터와 합쳐준다

fun getIssueList(owner : String, repo : String, page : Int) {

    CoroutineScope(Dispatchers.Default).launch{

        val result = issueRepository.getIssueList(owner, repo, page)
        withContext(Dispatchers.Main){

            val newList = mutableListOf<IssueUiData>()
            issuePage++

            _issueList.value?.let{
                newList.addAll(it)
                newList.addAll(result)
                _issueList.postValue(newList)
            }?:run{
                _issueList.postValue(result)
            }
        }
    }
}

• 맨위 스크롤시 갱신까지!!!
  • 주의!! View가 처음그려질때 항상 false 이므로, 저런식으로 if문 처리 해줘야함

binding.mainRecycler.addOnScrollListener(object : RecyclerView.OnScrollListener(){
    override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
        super.onScrolled(recyclerView, dx, dy)

        if(!binding.mainRecycler.canScrollVertically(1)){
            getIssueList(parentViewModel.getIssuePage())
        }

        if(!binding.mainRecycler.canScrollVertically(-1)){
            if (isInitState){
                isInitState = false
            } else{
                getIssueList(1)
            }
        }
    }
})