swift编程示例

1. 下载数据并输出

let url = URL(string: "https://www.apple.com")!
let task = URLSession.shared.downloadTask(with: url) { localURL, urlResponse, error in
        if let localURL = localURL {
                if let string = try? String(contentsOf: localURL) {
                    print(localURL)
                    print(string)
                }
            }
        }

每个应用程序都有一个沙箱存放自己的数据，沙箱中有不同的文件夹。下载后会把数据放到临时文件夹tmp中。注意这里URL的内容要是文本。

2. 从临时文件夹复制到文档文件夹

func getDocumentsDirectory() -> URL {
        let paths = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
        return paths[0]
    }


let fileManager = FileManager.default

let newsURL = self.getDocumentsDirectory().appendingPathComponent("news.mp3")
do {
    try fileManager.copyItem(at:localURL, to: newsURL)
}
catch let error as NSError {
    print("Ooops! Something went wrong: \(error)")
}

3. 下载文件并保存

let url = URL(string: "https://www.nhk.or.jp/r-news/ondemand/mp3/20200605170003_32512_3_1_2.mp3")!

        let task = URLSession.shared.downloadTask(with: url) { localURL, urlResponse, error in
            if let localURL = localURL {
               
                print(localURL)
            
                print(self.getDocumentsDirectory())
                let fileManager = FileManager.default

                // Copy 'hello.swift' to 'subfolder/hello.swift'
                let newsURL = self.getDocumentsDirectory().appendingPathComponent("news.mp3")
                do {
                    try fileManager.copyItem(at:localURL, to: newsURL)
                }
                catch let error as NSError {
                    print("Ooops! Something went wrong: \(error)")
                }
                    
            }
        }

        task.resume()