feat, refactor: addChild 방식 드롭다운 구현

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

@@ -0,0 +1,65 @@
+//
+//  UIViewController+Dropdown.swift
+//  koin
+//
+//  Created by 홍기정 on 11/1/26.
+//
+
+import UIKit
+
+// MARK: - UIViewController
+extension UIViewController {
+    var isPresentingDropdown: Bool {
+        children.contains(where: { $0 is KoinDropdownViewController })
+    }
+
+    @discardableResult
+    func presentDropdown(
+        anchor: UIView,
+        content: UIView & KoinDropdownContentView,
+        configuration: KoinDropdownConfiguration
+    ) -> KoinDropdownViewController? {
+        guard !isPresentingDropdown,
+              anchor.isDescendant(of: view) else { return nil }
+
+        view.endEditing(true)
+        let dropdown = KoinDropdownViewController(
+            anchor: anchor,
+            contentView: content,
+            configuration: configuration
+        )
+        addChild(dropdown)
+        dropdown.view.frame = view.bounds
+        view.addSubview(dropdown.view)
+        dropdown.didMove(toParent: self)
+        guard dropdown.presentDropdown() else {
+            dropdown.dismissDropdown(animated: false)
+            return nil
+        }
+        return dropdown
+    }
+}
+
+// MARK: - UIView
+extension UIView {
+    @discardableResult
+    func presentDropdown(
+        anchor: UIView,
+        content: UIView & KoinDropdownContentView,
+        configuration: KoinDropdownConfiguration
+    ) -> KoinDropdownViewController? {
+        // responder chain을 따라 올라가 이 view를 띄운 가장 가까운 VC를 찾는다.
+        var responder: UIResponder? = self
+        while let current = responder {
+            if let viewController = current as? UIViewController {
+                return viewController.presentDropdown(
+                    anchor: anchor,
+                    content: content,
+                    configuration: configuration
+                )
+            }
+            responder = current.next
+        }
+        return nil
+    }
+}

Koin/Core/View/UIKit/KoinDropdown/Helper/KoinDropdownAnimator.swift → Koin/Core/View/UIKit/KoinDropdown/KoinDropdownAnimator.swift

@@ -10,24 +10,30 @@ import UIKit
 @MainActor
 final class KoinDropdownAnimator {
 
+    // MARK: - Metric
     enum Metric {
         static let presentDuration: TimeInterval = 0.3
         static let presentBounce: CGFloat = 0.15
         static let dismissDuration: TimeInterval = 0.2
     }
 
-    private func hiddenTransform(travel: CGFloat) -> CGAffineTransform {
-        CGAffineTransform(translationX: 0, y: -travel)
+    // MARK: - Transform
+    private func hiddenTransform(hiddenOffsetY: CGFloat) -> CGAffineTransform {
+        CGAffineTransform(
+            translationX: 0,
+            y: hiddenOffsetY
+        )
     }
 
+    // MARK: - Present
     func present(
         view: UIView,
-        travel: CGFloat,
+        hiddenOffsetY: CGFloat,
         completion: (() -> Void)? = nil
     ) {
         view.isHidden = false
         view.alpha = 0
-        view.transform = hiddenTransform(travel: travel)
+        view.transform = hiddenTransform(hiddenOffsetY: hiddenOffsetY)
 
         UIView.animate(
             springDuration: Metric.presentDuration,
@@ -40,14 +46,15 @@ final class KoinDropdownAnimator {
         }
     }
 
+    // MARK: - Dismiss
     func dismiss(
         view: UIView,
-        travel: CGFloat,
+        hiddenOffsetY: CGFloat,
         completion: (() -> Void)? = nil
     ) {
         UIView.animate(springDuration: Metric.dismissDuration) {
             view.alpha = 0
-            view.transform = self.hiddenTransform(travel: travel)
+            view.transform = self.hiddenTransform(hiddenOffsetY: hiddenOffsetY)
         } completion: { _ in
             view.isHidden = true
             completion?()

Koin/Core/View/UIKit/KoinDropdown/KoinDropdownConfiguration.swift

@@ -8,10 +8,46 @@
 import UIKit
 
 struct KoinDropdownConfiguration {
-    let topPadding: CGFloat
+    // MARK: - Properties
+    let direction: Direction
     let shadow: Shadow
 }
 
+// MARK: - Direction
+extension KoinDropdownConfiguration {
+    /// 각 연관값의 spacing은 anchor와 dropdown 사이 간격이다.
+    enum Direction {
+        case down(spacing: CGFloat)
+        case auto(
+            downSpacing: CGFloat,
+            upSpacing: CGFloat
+        )
+    }
+
+    enum ResolvedDirection {
+        case down
+        case up
+    }
+
+    var isAutoDirection: Bool {
+        if case .auto = direction {
+            return true
+        }
+        return false
+    }
+
+    /// 실제로 연 방향에서 anchor와 dropdown 사이 간격을 반환한다.
+    func spacing(for resolvedDirection: ResolvedDirection) -> CGFloat {
+        switch direction {
+        case let .down(spacing):
+            return spacing
+        case let .auto(downSpacing, upSpacing):
+            return resolvedDirection == .down ? downSpacing : upSpacing
+        }
+    }
+}
+
+// MARK: - Shadow
 extension KoinDropdownConfiguration {
     enum Shadow {
         case shadow2
@@ -53,12 +89,12 @@ extension KoinDropdownConfiguration {
         }
     }
 
-    var shadowPadding: UIEdgeInsets {
+    func shadowPadding(for direction: ResolvedDirection) -> UIEdgeInsets {
         let base = max(0, shadow.blur + shadow.spread)
         return UIEdgeInsets(
-            top: 0,
+            top: direction == .up ? base + max(0, -shadow.offset.y) : 0,
             left: base + max(0, -shadow.offset.x),
-            bottom: base + max(0, shadow.offset.y),
+            bottom: direction == .down ? base + max(0, shadow.offset.y) : 0,
             right: base + max(0, shadow.offset.x)
         )
     }

Koin/Core/View/UIKit/KoinDropdown/KoinDropdownContentView.swift

@@ -0,0 +1,15 @@
+//
+//  KoinDropdownContentView.swift
+//  koin
+//
+//  Created by 홍기정 on 11/1/26.
+//
+
+import UIKit
+import Combine
+
+@MainActor
+protocol KoinDropdownContentView: AnyObject {
+    var dismissTappedPublisher: AnyPublisher<Void, Never> { get }
+    var height: CGFloat { get }
+}