func checkAPIHealth(completion: @escaping (Bool) -> Void)

func fetchItemList(pageNo: Int, pageCount: Int, 
              completion: @escaping (Result<ItemList, NetworkError>) -> Void)

func fetchItem(productId: Int, 
          completion: @escaping (Result<Item, NetworkError>) -> ())

func createRequestBody(params: [String: Data], images: [UIImage], boundary: String) -> Data 

func addItem(params: [String: Any], images: [UIImage], completion: @escaping (Result<Item, NetworkError>) -> ())

func deleteURI(productId: Int, password: String,  completion: @escaping (Result<String, NetworkError>) -> ())

func deleteItem(productId: Int, password: String, completion: @escaping (Result<Item, NetworkError>) -> ()) 

func editItem(productId: Int, params: [String: Any], completion: @escaping (Result<Item, NetworkError>) -> ())

final class ImageCacheManager {
    static let shared = NSCache<NSString, UIImage>()
    private init() {}
}

 static func showLoading() {
        DispatchQueue.main.async {
            guard let window = UIApplication.shared.windows.last else { return }
            let loadingIndicatorView: UIActivityIndicatorView
            if let existedView = window.subviews.first(where: { $0 is UIActivityIndicatorView } ) as? UIActivityIndicatorView {
                loadingIndicatorView = existedView
            } else {
                loadingIndicatorView = UIActivityIndicatorView(style: .large)
                loadingIndicatorView.frame = window.frame
                loadingIndicatorView.color = .brown
                loadingIndicatorView.backgroundColor = .gray
                window.addSubview(loadingIndicatorView)
            }

            loadingIndicatorView.startAnimating()
        }
    }

static func hideLoading() {
        DispatchQueue.main.async {
            guard let window = UIApplication.shared.windows.last else { return }
            window.subviews.filter({ $0 is UIActivityIndicatorView }).forEach { $0.removeFromSuperview()
            }
        }
    }

@objc private func changeItemView(_ sender: UISegmentedControl) {
    showCollectionType(segmentIndex: sender.selectedSegmentIndex)
}

private func showCollectionType(segmentIndex: Int) {
    if segmentIndex == 0 {
        self.gridCollectionView.isHidden = true
        self.listCollectionView.isHidden = false
    } else {
        self.listCollectionView.isHidden = true
        self.gridCollectionView.isHidden = false
    }
}

func showAlert(title, message, actionMessage, dismiss)

@objc func doneButtonTapped()

@objc private func presentAlbum()

func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any])

private func fetchItem()

extension UIImage {
    func compressTo(expectedSizeInKb:Int) -> Data? {
        let sizeInBytes = expectedSizeInKb * 1024
        var needCompress: Bool = true
        var imgData: Data?
        var compressingValue: CGFloat = 1.0
        
        while (needCompress && compressingValue > 0.0) {
            if let data: Data = self.jpegData(compressionQuality: compressingValue) {
            if data.count < sizeInBytes {
                needCompress = false
                imgData = data
            } else {
                compressingValue -= 0.1
            }
        }
    }
        
    if let data = imgData {
        if (data.count < sizeInBytes) {
            return data
        }
    }
        return nil
    }
}

func createRequestBody(params: [String: Any], images: [UIImage], boundary: String) -> Data {
        let newLine = "\r\n"
        let boundaryPrefix = "--\(boundary + newLine)"
        
        var body = Data()
        
        for (key, value) in params {
            body.append(boundaryPrefix)
            body.append("Content-Disposition: form-data; name=\"\(key)\"\(newLine + newLine)")
            body.append(value)
            body.append(newLine)
        }
    
    // image 파일추가 부분
}
       
let params: [String: Any] = ["name": "눈온다", "description": "간식", "price": 1000, "currency": "KRW", "stock": 1, "secret": "snnq45ezg2tn9amy"]
request.httpBody = createRequestBody(params: ["params" : jsonData], images: [UIImage()], boundary: boundary)
       

let params: [String: Any] = ["name": "눈온다", "description": "간식", "price": 1000, "currency": "KRW", "stock": 1, "secret": "snnq45ezg2tn9amy"]
guard let jsonData = try? JSONSerialization.data(withJSONObject: params) else { return }
request.httpBody = createRequestBody(params: ["params" : jsonData], images: [UIImage()], boundary: boundary)