1. 데이터 새로고침을 할때 사용(테이블뷰나 콜렉션뷰 데이터를 새로고침할때 유용)
let refreshControl = UIRefreshControl() tableView.refreshControl = refreshControl refreshControl.addTarget(self, action: #selector(handleRefresh), for: .valueChanged)
// 시작
refreshControl.beginFreshing()
// 종료
refreshControl.endFreshing()
## 검색기능