//Properties
     @Published var filteredCurrency = "KZT"

 //.Filter call
.filter({ Currency in
                        Currency.currencyName == self.filteredCurrency
                    })

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这是一个答案，因为我相信我调用了一个.filter，并解决了Currency.currency名称将等于我给它的一个属性
现在我的代码看起来像这样

import SwiftUI

class FetchData: ObservableObject {
    
    @Published var coversionData: [Currency] = []
    @Published var baseCode = "USD"
    @Published var filteredCurrency = "KZT"
    
init() {
    fetch()
}

func fetch() {
    
    let url = "https://open.exchangerate-api.com/v6/latest?base=\(baseCode)"
    
    let session = URLSession(configuration: .default)
    session.dataTask(with: URL(string: url)!) { data, _, _ in
        
        guard let JSONData = data else {return}
        
        do {
            let conversion = try JSONDecoder().decode(Conversion.self, from: JSONData)
            
            DispatchQueue.main.async {
                self.coversionData = conversion.rates.compactMap({ (key,value) -> Currency? in
                    return Currency(currencyName: key, currencyValue: value)
                })
                .filter({ Currency in
                    Currency.currencyName == self.filteredCurrency
                })
            }
        }
        catch {
            print(error)
        }
    }
    .resume()
}

func updateData(baseCode: String) {
    
    self.baseCode = baseCode
    

       self.coversionData.removeAll()
        fetch()
        
    }
    
}

型