符合 NSCoding

Question

我一辈子都弄不明白为什么我会收到此 class 不符合 NSCoding 协议的错误。也许另一双眼睛会有所帮助。我试图添加注释以明确每个函数在做什么。

import Foundation
import UIKit

class Search: NSObject, NSCoding {

// Global Variables
var articlePicture: UIImage!
var articleTitle: String

// MARK: Public Init
init(articlePicture: UIImage, articleTitle: String) {
    self.articlePicture = articlePicture
    self.articleTitle = articleTitle
}

// Required NSCoding Protocol
required convenience init?(coder decoder: NSCoder) {
    guard let articlePicture = decoder.decodeObject(forKey: "articlePicture") as? UIImage,
        let articleTitle = decoder.decodeObject(forKey: "articleTitle") as? String
        else { return nil }

    self.init(
        articlePicture: articlePicture,
        articleTitle: articleTitle
    )
}

// Required NSCoding Protocal
func encodeWithCoder(coder: NSCoder) {
    coder.encode(self.articlePicture, forKey: "articlePicture")
    coder.encode(self.articleTitle, forKey: "articleTitle")
}

// Initialize [Search]
static var searches = [Search]()

static func getSearches() -> [Search]{
    return searches
}

static func setSearch(search: Search){
    searches.append(search)
}

// NSUserDefaults Searches Array funcs
static func saveSearches(){
    let searchData = NSKeyedArchiver.archivedData(withRootObject: searches)
    UserDefaults.standard.set(searchData, forKey: "searches")
}

static func loadSearches() -> [Search]{
    let searchData = UserDefaults.standard.object(forKey: "searches") as? NSData

    if let searchData = searchData {
        searches = (NSKeyedUnarchiver.unarchiveObject(with: searchData as Data) as? [Search])!
        return searches
    }
    return searches
}
}

Answer 1

提示：按Cmd + 4打开问题导航器，Xcode会告诉你更多细节。

在Swift3中，编码函数发生了变化：

func encodeWithCoder(coder: NSCoder) {
    // Swift 2 and older
}

func encode(with coder: NSCoder) {
    // Swift 3
}

更改方法的签名，应该没问题

Answer 2

在Swift4中还有一种方法encode/decode类。现在您只需遵守协议 Codable。不再需要编写所有编码和解码，它支持类没有 NSObject & 枚举 & 结构。

final class Search: Codable {

}

有关详细信息，请阅读 https://developer.apple.com/documentation/swift/codable

符合 NSCoding

Conforming to NSCoding

nsuserdefaults

nscoding

swift