快速 JSON 解码错误："Expected to decode Dictionary<String, Any> but found an array instead."

Question

我在解码以下JSON(它完全包含在数组中(时遇到问题：

[
{
"symbol": "AAPL",
"name": "Apple Inc.",
"price": 254.81,
"changesPercentage": 2.85,
"change": 7.07,
"dayLow": 249.4,
"dayHigh": 255.5,
"yearHigh": 327.85,
"yearLow": 170.27,
"marketCap": 1114915995648,
"priceAvg50": 281.9003,
"priceAvg200": 270.52628,
"volume": 37900589,
"avgVolume": 48846970,
"exhange": "NASDAQ",
"open": 250.74,
"previousClose": 247.74,
"eps": 12.595,
"pe": 20.231043,
"earningsAnnouncement": "2020-01-28T21:30:00.000+0000",
"sharesOutstanding": 4375479808,
"timestamp": 1585600706
}
]

这是我用来解码的结构：

struct StockData: Codable {
let name: String
let exchange: String
let price: Double
let yearLow: Double
let yearHigh: Double
let marketCap: Double
}

这是我解码它的代码：

func parseJSON(_ stockData: Data) -> StockModel? {
let decoder = JSONDecoder()
do{
let decodedData = try decoder.decode(StockData.self, from: stockData)
let name = decodedData.name
let exchange = decodedData.exchange
let price = String(decodedData.price)
let yearLow = String(decodedData.yearLow)
let yearHigh = String(decodedData.yearHigh)
let marketCap = String(decodedData.marketCap)
let stockModel = StockModel(name: name, exchange: exchange, stockAttributes: [price, marketCap, yearLow, yearHigh])
return stockModel
}catch{
print(error)
return nil
}
}

我试着把它做成：try decoder.decode([StockData].self, from: stockData)，这样stockData就被括在括号里，表明它是一个数组，但我得到了错误

如何解码完全包含在数组中的JSON？

Answer 1

[StockData].self是对的。错误(和JSON(清楚地表明根对象是一个数组。

要提取数据，请获取阵列的第一项

func parseJSON(_ stockData: Data) -> StockModel? {
let decoder = JSONDecoder()
do{
let decodedData = try decoder.decode([StockData].self, from: stockData)
guard let stock = decodedData.first else { return nil }
let name = stock.name
let exchange = stock.exchange
let price = String(stock.price)
let yearLow = String(stock.yearLow)
let yearHigh = String(stock.yearHigh)
let marketCap = String(stock.marketCap)
let stockModel = StockModel(name: name, exchange: exchange, stockAttributes: [price, marketCap, yearLow, yearHigh])
return stockModel
} catch {
print(error)
return nil
}
}

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