如何在swift中下载文件？

在Swift中下载文件，通常可以使用URLSession类来实现。下面是一个简单的示例代码，展示了如何使用URLSession下载文件并保存到本地。

import Foundation

func downloadFile(from url: URL, to destination: URL, completion: @escaping (Result<URL, Error>) -> Void) {
    let task = URLSession.shared.downloadTask(with: url) { (location, response, error) in
        if let error = error {
            completion(.failure(error))
            return
        }
        
        guard let location = location else {
            completion(.failure(NSError(domain: "", code: -1, userInfo: [NSLocalizedDescriptionKey: "下载失败，未获取到文件位置"])))
            return
        }
        
        do {
            // 确保目标目录存在
            try FileManager.default.createDirectories(for: destination.deletingLastPathComponent(), withIntermediateDirectories: true)
            
            // 将下载的文件移动到目标路径
            try FileManager.default.moveItem(at: location, to: destination)
            
            completion(.success(destination))
        } catch {
            completion(.failure(error))
        }
    }
    
    task.resume()
}

// 使用示例
let fileURL = URL(string: "https://example.com/path/to/file.zip")!
let destinationURL = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!.appendingPathComponent("file.zip")

downloadFile(from: fileURL, to: destinationURL) { result in
    switch result {
    case .success(let url):
        print("文件下载成功，保存路径: \(url)")
    case .failure(let error):
        print("文件下载失败: \(error.localizedDescription)")
    }
}