feat, refactor: addChild 방식 바텀시트 구현

Koin/Core/Extensions/UIKit/UIViewController+KoinBottomSheet.swift

@@ -0,0 +1,61 @@
+//
+//  UIViewController+KoinBottomSheet.swift
+//  koin
+//
+//  Created by 홍기정 on 10/28/26.
+//
+
+import UIKit
+import SnapKit
+
+extension UIViewController {
+    @discardableResult
+    func presentBottomSheet(
+        _ contentView: some KoinBottomSheetContent,
+        configuration: KoinBottomSheetConfiguration = .init()
+    ) -> KoinBottomSheetController? {
+        guard let window = viewIfLoaded?.window else { return nil }
+        assert(contentView.superview == nil, "Create new content for every KoinBottomSheet presentation")
+        window.endEditing(true)
+
+        let host: UIViewController
+        switch configuration.style {
+        case .modal:
+            host = tabBarController ?? navigationController ?? self
+        case .nonModal:
+            host = self
+        }
+        // 닫히는 중인 시트는 애니메이션 동안 붙어 있지만, 활성 시트 조회에서는 빠진다.
+        activeBottomSheets.forEach { $0.dismissForReplacement() }
+
+        let sheet = KoinBottomSheetController(
+            contentViewController: KoinBottomSheetContentViewController(contentView: contentView),
+            owner: self,
+            configuration: configuration
+        )
+        contentView.delegate = sheet
+        host.addChild(sheet)
+        host.view.addSubview(sheet.view)
+        sheet.view.snp.makeConstraints { $0.edges.equalToSuperview() }
+        sheet.didMove(toParent: host)
+        sheet.presentSheet()
+        return sheet
+    }
+
+    func dismissBottomSheet() {
+        guard viewIfLoaded?.window != nil else { return }
+        let modalHost = tabBarController ?? navigationController ?? self
+        activeBottomSheets
+            .filter { $0.owner === self || $0.parent === modalHost }
+            .forEach { $0.dismiss() }
+    }
+
+    /// 같은 화면의 시트만 본다: 자신과 modal host의 직속 child.
+    private var activeBottomSheets: [KoinBottomSheetController] {
+        let modalHost = tabBarController ?? navigationController ?? self
+        let candidates = modalHost === self ? children : children + modalHost.children
+        return candidates
+            .compactMap { $0 as? KoinBottomSheetController }
+            .filter { $0.isActive }
+    }
+}