Fairly straight forward JSONDecoder with a single nest

Swift JSON Decoder

import Foundation

let i = """
{
    "Global Quote":{
        "01. symbol": "MSFT",
        "02. open": "157.1304",
        "03. high": "157.7000",
        "04. low": "151.1500",
        "05. price": "153.6300",
        "06. volume": "56029209",
        "07. latest trading day": "2020-03-11",
        "08. previous close": "160.9200",
        "09. change": "-7.2900",
        "10. change percent": "-4.5302%"
    }
}
""".data(using: .utf8)

struct Quote: Decodable{
    var symbol: String
    var open: String
    var high: String
    var low: String
    var price: String
    var volume: String
    var latestTrade: String
    var previousClose: String
    var change: String
    var changePercent: String

    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: DecodingKeys.self)
        symbol = try container.decode(String.self, forKey: .symbol)
        open = try container.decode(String.self, forKey: .open)
        high = try container.decode(String.self, forKey: .high)
        low = try container.decode(String.self, forKey: .low)
        price = try container.decode(String.self, forKey: .price)
        volume = try container.decode(String.self, forKey: .volume)
        latestTrade = try container.decode(String.self, forKey: .latestTrade)
        previousClose = try container.decode(String.self, forKey: .previousClose)
        change = try container.decode(String.self, forKey: .change)
        changePercent = try container.decode(String.self, forKey: .changePercent)
    }
}

struct Root: Decodable {
    var quote: Quote

    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: DecodingKeys.self)
        quote = try container.decode(Quote.self, forKey: .quote)
    }
}

enum DecodingKeys: String, CodingKey {
    case quote = "Global Quote"
    case symbol = "01. symbol"
    case open = "02. open"
    case high = "03. high"
    case low = "04. low"
    case price = "05. price"
    case volume = "06. volume"
    case latestTrade = "07. latest trading day"
    case previousClose = "08. previous close"
    case change = "09. change"
    case changePercent = "10. change percent"
}

let decoder = JSONDecoder()

do {
    let info =  try decoder.decode(Root.self, from: i!)
    print(info.quote.symbol)
} catch let e{
    print(e)
}