Vanilla View Swift

BaseView.swift

import UIKit

/// Represents the internal state of the view.
public protocol BaseViewState {
  init()
}

/// Empty view state.
public final class BaseViewNullState: BaseViewState {
  public init() {
    // No-op.
  }
}

/// The properties passed down to the view.
public protocol BaseViewProps {
  init()
}

/// Empty properties.
public final class BaseViewNullProps: BaseViewProps {
  public init() {
    // No-op.
  }
}

public protocol BaseViewDelegate: AnyObject { }

public class BaseView<
  StateType: BaseViewState,
  PropsType: BaseViewProps>: UIView {

  /// The view delegate.
  public weak var delegate: BaseViewDelegate?
  /// The view current state.
  public private(set) var state = StateType() {
    didSet {
      onStateChange(old: oldValue, new: state)
    }
  }
  /// The view properties.
  public var props = PropsType() {
    didSet {
      onPropsChange(old: oldValue, new: props)
    }
  }

  public override init(frame: CGRect) {
    super.init(frame: frame)
    initSubviews()
  }

  public required init?(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
    initSubviews()
  }
  /// Initialize all of the subviews.
  open func initSubviews() {
    // Subviews configuration code here.
  }
  /// The `props` member changed.
  /// - note: Subviews to override this method if necessary, the default implementation triggers
  /// `setNeedsLayout`.
  open func onPropsChange(old: PropsType, new: PropsType) {
    // Subviews to override this method if necessary.
    setNeedsLayout()
  }
  /// The `props` member changed.
  /// - note: Subviews to override this method if necessary, the default implementation triggers
  /// `setNeedsLayout`.
  open func onStateChange(old: StateType, new: StateType) {
    // Subviews to override this method if necessary.
    setNeedsLayout()
  }
}

public extension UIResponder {
  /// Returns the parent view controller for this `UIResponder`.
  public func viewControllerForAncestor() -> UIViewController? {
    if self.next is UIViewController {
      return self.next as? UIViewController
    } else {
      if self.next != nil {
        return (self.next!).viewControllerForAncestor()
      }
      else {return nil}
    }
  }
}