KeyValueObserverResult.swift

//
//  KeyValueObserverResult.swift
//  JSTColorPicker
//
//  Created by Rachel on 4/14/21.
//  Copyright © 2021 JST. All rights reserved.
//

import Foundation

public struct KeyValueObserverResult<T: Any> {

    public private(set) var change: [NSKeyValueChangeKey: Any]

    public private(set) var kind: NSKeyValueChange

    init?(change: [NSKeyValueChangeKey: Any]) {
        self.change = change
        guard
            let changeKindNumberValue = change[.kindKey] as? NSNumber,
            let changeKindEnumValue = NSKeyValueChange(rawValue: changeKindNumberValue.uintValue) else {
            return nil
        }
        kind = changeKindEnumValue
    }

    // MARK: -

    public var valueNew: T? {
        return change[.newKey] as? T
    }

    public var valueOld: T? {
        return change[.oldKey] as? T
    }

    var isPrior: Bool {
        return (change[.notificationIsPriorKey] as? NSNumber)?.boolValue ?? false
    }

    var indexes: NSIndexSet? {
        return change[.indexesKey] as? NSIndexSet
    }
}