我已经阅读了很多教程,并在SO上搜索了答案;
Decoding Nested JSON with Optional Values Swift 4
Swift 4 Not decoding JSON optional properly
使用以下代码解码可选对象似乎没有问题。显然我在做错事,但这是什么!?
部分代码:
struct ProductInfo: Codable {
var name: String?
let images: [Image]
var ingredients: String?
let origin: [Origin]
let producer: Producer
enum CodingKeys: String, CodingKey {
case name = "Artikelbenamning"
case images = "Bilder"
case ingredients = "Ingrediensforteckning"
case origin = "Tillverkningslander"
case producer = "Varumarke"
}
init(from decoder: Decoder) throws {
let values = try decoder.container(keyedBy: CodingKeys.self)
name = try? values.decodeIfPresent(String.self, forKey: .name)!
images = try values.decodeIfPresent([Image].self, forKey: .images)!
ingredients = try? values.decodeIfPresent(String.self, forKey: .ingredients)!
origin = try values.decodeIfPresent([Origin].self, forKey: .origin)!
producer = try values.decodeIfPresent(Producer.self, forKey: .producer)!
}
}
该应用程序查询产品数据库。商品不存在时,返回以下json。
尝试在init(from :)中解码nil名称(“ json中的Artikelbenamning”)时,应用崩溃。{
"GTIN": null,
"TillverkarensArtikelnummer": null,
"Artikelbenamning": null,
"RegleratProduktnamn": null,
"Forvaringsinstruktion": null,
"Variabelmattsindikator": false,
"Bruttovikt": null,
"Bredd": null,
"Djup": null,
"Hojd": null,
"Returemballage": false,
"FarligtGodsKod": null,
"FarligtGodsKlass": null,
"FarligtGodsForpackningsgrupp": null,
"GPCKod": null,
"GiltigFROM": null,
"Publiceringsdatum": null,
"FakturerbarEnhet": false,
"Slutdatum": null,
"GiltighetsdatumPris": null,
"Tillganglighetstidpunkt": null,
"SistaTillganglighetstidpunkt": null,
"SkapadDatum": null,
"SenastAndradDatum": null,
"Flampunkt": null,
"KodBegransadMangd": null,
"OfficiellTransportbenamning": null,
"OspecificeradTransportbenamning": null,
"TunnelrestriktionADR": null,
"KlassificeringskodFarligtgods": null,
"Transportkategori": null,
"Konsumentartikel": false,
"BestallningsbarForpackning": false,
"RabattOlaglig": null,
"Garantiloptid": 0,
"Konsumentdatum": null,
"Tjanst": false,
"Sasongsindikator": null,
"Engangskop": null,
"AntalReturnerbaraEnheter": 0,
"Staplingsriktning": null,
"Staplingstyp": null,
"MaxTransportTemperatur": 0.0,
"MinTransportTemperatur": 0.0,
"Anvandningsinstruktioner": null,
"HallbarhetEfterOppning": 0,
"Riskfras": null,
"KodlistutgivareRiskfras": null,
"Klassificeringssystem": null,
"FarligtGodsBegransadMangd": null,
"FarligtGodsOvrigInfo": null,
"FarligtGodsSarbestammelser": null,
"T3495_Artikelavisering": null,
"T4032_TypAvUtgangsdatum": null,
"T3742_ForstaLeveransdatum": null,
"Undervarumarke": null,
"Niva": null,
"Produktbladslank": null,
"KompletterandeProduktklass": null,
"T4200_AllmänPubliceringstidpunkt": null,
"T3848_TypAvTryckkanslighet": null,
"Varningsetiketter": [],
"Sasongskoder": [],
"Produktklasser": [],
"MaskinellMarkningar": [],
"Bilder": [],
"ReferenserTillAndraArtiklar": [],
"MSRKritierier": [],
"Kravspecifikationer": [],
"Receptlinks": [],
"Allergener": [],
"Markningar": [],
"Ingredienser": [],
"Tillagningsinformation": [],
"Tillverkningslander": [],
"Naringsinfo": [],
"Serveringsforslag": [],
"Diettyper": [],
"Tillagningsmetoder": [],
"Farger": [],
"VillkorForsaljning": [],
"Varumarke": {
"Varumarke": null,
"AgareGLN": null,
"AgareNamn": null,
"Tillverkare": {
"Namn": null,
"EAN": null
}
},
"Nettoinnehall": [],
"Kontakter": [],
"Faroangivelser": [],
"Sakerhet": [],
"Forpackningar": [],
"Tillsatser": [],
"Substanser": [],
"Fangstzoner": [],
"Marknadsbudskap": null,
"KortMarknadsbudskap": null,
"Komponenter": null
}
答案 0 :(得分:0)
在这种情况下,API decodeIfPresent
毫无意义,因为存在密钥 。
具有null
值的 existing 键和 missing 键是两种不同的情况。
也不要在init(from decoder
方法中强行打开包装。
有两种选择:
init
方法,然后可选的struct成员处理null
值。使用常规decode
并忽略该错误
name = try? values.decode(String.self, forKey: .name)