[GWL-51] Design System Page Control 생성 (#54)

* feat: GWPageControl 구현

* feat: GWRoundedShadwView 구현

* chor: 접근 제어자 수정

* feat: 접근 제어자 수정, GWShadow 파일 분리

iOS/Projects/Shared/DesignSystem/Sources/GWPageConrol.swift

@@ -0,0 +1,123 @@
+//
+//  GWPageConrol.swift
+//  DesignSystem
+//
+//  Created by MaraMincho on 11/16/23.
+//  Copyright © 2023 kr.codesquad.boostcamp8. All rights reserved.
+//
+
+import Foundation
+
+import UIKit
+
+// MARK: - GWPageControl
+
+public final class GWPageControl: UIView {
+  let countOfPage: Int
+  var currentPageIndex: Int = 0
+  let spacing: CGFloat = 8
+  var pages: [GWRoundShadowView] = []
+  var pageswidthConstraint: [NSLayoutConstraint] = []
+
+  // MARK: - 과연 UIVIew를 optional로 만드는게 맞을까?
+
+  /// 2 와 5 사이 숫자를 입력하세요 아닐경우 nil이 리턴됩니다.
+  public init(count: Int = 2) {
+    countOfPage = (UIPageControlDefaultProperty.range).contains(count) ?
+      count :
+      UIPageControlDefaultProperty.numOfMinPage
+
+    super.init(frame: .init(origin: .zero, size: CGSize(width: 60, height: 10)))
+
+    makePages()
+    makePageConstraints()
+    selectPage(at: 0)
+  }
+
+  @available(*, unavailable)
+  required init?(coder _: NSCoder) {
+    fatalError()
+  }
+
+  private enum UIPageControlDefaultProperty {
+    static let numOfMinPage = 2
+    static let numOfMaxPage = 5
+
+    static let range = numOfMaxPage ... numOfMaxPage
+
+    static let selectedPageColor = DesignSystemColor.main03
+    static let deselectedPageColor = DesignSystemColor.gray02
+
+    static let selectedPageWidth: CGFloat = 40
+    static let deselectedPageWidth: CGFloat = 10
+  }
+}
+
+private extension GWPageControl {
+  func makePages() {
+    pages = (0 ..< countOfPage).enumerated().map { _, _ -> GWRoundShadowView in
+      return pageViewObject
+    }
+  }
+
+  func makePageConstraints() {
+    var targetLeadingAnchor = safeAreaLayoutGuide.leadingAnchor
+    var targetSpacing: CGFloat = 0
+
+    pages.forEach { page in
+      // 중요: 맨 처음 Page객체는 왼쪽으로 붙여야 하기에 필수 불가결적으로 다음 로직이 필요합니다.
+      if targetLeadingAnchor != safeAreaLayoutGuide.leadingAnchor {
+        targetSpacing = spacing
+      }
+
+      addSubview(page)
+      page.leadingAnchor.constraint(equalTo: targetLeadingAnchor, constant: targetSpacing).isActive = true
+      page.heightAnchor.constraint(equalToConstant: spacing).isActive = true
+
+      let widthAnchor = page.widthAnchor.constraint(equalToConstant: UIPageControlDefaultProperty.deselectedPageWidth)
+      widthAnchor.isActive = true
+      pageswidthConstraint.append(widthAnchor)
+
+      targetLeadingAnchor = page.trailingAnchor
+    }
+  }
+
+  var pageViewObject: GWRoundShadowView {
+    let view = GWRoundShadowView(
+      shadow: .init(
+        shadowColor: DesignSystemColor.gray02.cgColor,
+        shadowOffset: CGSize(width: 0, height: 1),
+        shadowOpacity: 0.2, shadowRadius: 4.0
+      ),
+      cornerRadius: 4,
+      backgroundColor: DesignSystemColor.gray03.cgColor
+    )
+
+    view.translatesAutoresizingMaskIntoConstraints = false
+    return view
+  }
+}
+
+public extension GWPageControl {
+  func selectPage(at pageIndex: Int) {
+    guard 0 ..< pages.count ~= pageIndex else {
+      return
+    }
+    let page = pages[pageIndex]
+    page.update(color: UIPageControlDefaultProperty.selectedPageColor)
+
+    let pageWidthConstraint = pageswidthConstraint[pageIndex]
+    pageWidthConstraint.constant = UIPageControlDefaultProperty.selectedPageWidth
+  }
+
+  func deselectPage(at pageIndex: Int) {
+    guard 0 ..< pages.count ~= pageIndex else {
+      return
+    }
+    let page = pages[pageIndex]
+    page.update(color: UIPageControlDefaultProperty.deselectedPageColor)
+
+    let pageWidthConstraint = pageswidthConstraint[pageIndex]
+    pageWidthConstraint.constant = UIPageControlDefaultProperty.deselectedPageWidth
+  }
+}

iOS/Projects/Shared/DesignSystem/Sources/GWRoundShadowView.swift

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+//
+//  GWRoundShadowView.swift
+//  DesignSystem
+//
+//  Created by MaraMincho on 11/16/23.
+//  Copyright © 2023 kr.codesquad.boostcamp8. All rights reserved.
+//
+
+import UIKit
+
+// MARK: - GWRoundShadowView
+
+public final class GWRoundShadowView: UIView {
+  let containerView = UIView()
+  let cornerRadius: CGFloat
+  let customShadow: GWShadow
+  private var shadowLayer: CAShapeLayer!
+  private var fillColor: CGColor = UIColor.blue.cgColor
+
+  public func update(color: UIColor) {
+    fillColor = color.cgColor
+  }
+
+  override public func layoutSubviews() {
+    super.layoutSubviews()
+    if shadowLayer == nil {
+      shadowLayer = CAShapeLayer()
+
+      shadowLayer.path = UIBezierPath(roundedRect: bounds, cornerRadius: cornerRadius).cgPath
+      shadowLayer.fillColor = fillColor
+
+      shadowLayer.shadowColor = customShadow.shadowColor
+      shadowLayer.shadowPath = shadowLayer.path
+      shadowLayer.shadowOffset = customShadow.shadowOffset
+      shadowLayer.shadowOpacity = customShadow.shadowOpacity
+      shadowLayer.shadowRadius = customShadow.shadowRadius
+
+      layer.insertSublayer(shadowLayer, at: 0)
+    }
+
+    if shadowLayer.fillColor != fillColor {
+      shadowLayer.fillColor = fillColor
+    }
+  }
+
+  public init(shadow: GWShadow, cornerRadius: CGFloat, backgroundColor: CGColor) {
+    customShadow = shadow
+    self.cornerRadius = cornerRadius
+    fillColor = backgroundColor
+    super.init(frame: .zero)
+  }
+
+  @available(*, unavailable)
+  required init?(coder _: NSCoder) {
+    fatalError("init(coder:) has not been implemented")
+  }
+}

iOS/Projects/Shared/DesignSystem/Sources/GWShadow.swift

@@ -0,0 +1,17 @@
+//
+//  GWShadow.swift
+//  DesignSystem
+//
+//  Created by MaraMincho on 11/16/23.
+//  Copyright © 2023 kr.codesquad.boostcamp8. All rights reserved.
+//
+import CoreGraphics
+
+// MARK: - GWShadow
+
+public struct GWShadow {
+  let shadowColor: CGColor
+  let shadowOffset: CGSize
+  let shadowOpacity: Float
+  let shadowRadius: CGFloat
+}