Extensions.swift

import Foundation
import SwiftUI
import UIKit

/**
 Helper used to render UIView inside of SwiftUI.
 */
struct RepresentableView: UIViewRepresentable {
  var view: UIView

  // Adding a wrapper UIView to avoid SwiftUI directly managing React Native views.
  // This fixes issues with incorrect layout rendering.
  func makeUIView(context: Context) -> UIView {
    let wrapper = UIView()
    wrapper.addSubview(view)
    return wrapper
  }

  func updateUIView(_ uiView: UIView, context: Context) {}
}

extension Collection {
  // Returns the element at the specified index if it is within bounds, otherwise nil.
  subscript(safe index: Index) -> Element? {
    indices.contains(index) ? self[index] : nil
  }
}

extension UIView {
  func pinEdges(to other: UIView) {
    NSLayoutConstraint.activate([
      leadingAnchor.constraint(equalTo: other.leadingAnchor),
      trailingAnchor.constraint(equalTo: other.trailingAnchor),
      topAnchor.constraint(equalTo: other.topAnchor),
      bottomAnchor.constraint(equalTo: other.bottomAnchor)
    ])
  }
}

extension UIHostingController {
  convenience public init(rootView: Content, ignoreSafeArea: Bool) {
    self.init(rootView: rootView)

    if ignoreSafeArea {
      disableSafeArea()
    }
  }

  /// Disables safe area insets by dynamically subclassing the hosting controller's view
  /// and overriding safeAreaInsets to return .zero.
  func disableSafeArea() {
    guard let viewClass = object_getClass(view) else { return }

    let viewSubclassName = String(cString: class_getName(viewClass)).appending("_IgnoreSafeArea")
    if let viewSubclass = NSClassFromString(viewSubclassName) {
      object_setClass(view, viewSubclass)
    }
    else {
      guard let viewClassNameUtf8 = (viewSubclassName as NSString).utf8String else { return }
      guard let viewSubclass = objc_allocateClassPair(viewClass, viewClassNameUtf8, 0) else { return }

      if let method = class_getInstanceMethod(UIView.self, #selector(getter: UIView.safeAreaInsets)) {
        let safeAreaInsets: @convention(block) (AnyObject) -> UIEdgeInsets = { _ in
          return .zero
        }
        class_addMethod(viewSubclass, #selector(getter: UIView.safeAreaInsets), imp_implementationWithBlock(safeAreaInsets), method_getTypeEncoding(method))
      }

      objc_registerClassPair(viewSubclass)
      object_setClass(view, viewSubclass)
    }
  }
}