将文件保存在 swift 3 的文档目录中？

Question

我正在使用以下代码将文件保存在 swift 3 的文档目录中：

fileManager = FileManager.default
// let documentDirectory = fileManager?.urls(for: .documentDirectory, in: .userDomainMask).first as String
var path = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0] as String
path = path + name

let image = #imageLiteral(resourceName: "Notifications")
let imageData = UIImageJPEGRepresentation(image, 0.5)
let bool = fileManager?.createFile(atPath: path, contents: imageData, attributes: nil)

print("bool is \(bool)")
return true

但是正如您所看到的，我没有使用filemanager来获取文档目录路径，因为filemanager只提供 URL 而不是字符串。

问题：

• 如何从文件管理器获取字符串？
• 我的代码有没有崩溃的可能？

Answer 1

请换个角度思考。

URL是处理文件路径的推荐方式，因为它包含用于添加和删除路径组件和扩展的所有便捷方法——而不是 Apple 从中删除这些方法的String 。

不鼓励您连接路径，例如path = path + name 。 这很容易出错，因为您负责所有斜杠路径分隔符。

此外，您不需要使用FileManager创建文件。 Data有一种将数据写入磁盘的方法。

let fileManager = FileManager.default
do {
    let documentDirectory = try fileManager.url(for: .documentDirectory, in: .userDomainMask, appropriateFor:nil, create:false)
    let fileURL = documentDirectory.appendingPathComponent(name)
    let image = #imageLiteral(resourceName: "Notifications")
    if let imageData = image.jpegData(compressionQuality: 0.5) {
        try imageData.write(to: fileURL)
        return true
    }
} catch {
    print(error)
}
return false

Answer 2

按照vadian给出的上述示例，您需要在文档目录中保存（数据）文件的唯一行是：

尝试 imageData.write(to: fileURL)

获取文件路径是有趣的部分

例如：创建文件路径

 func createNewDirPath( )->URL{ 

let dirPathNoScheme = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0] as String

    //add directory path file Scheme;  some operations fail w/out it
    let dirPath = "file://\(dirPathNoScheme)"
    //name your file, make sure you get the ext right .mp3/.wav/.m4a/.mov/.whatever
    let fileName = "thisIsYourFileName.mov"
    let pathArray = [dirPath, fileName]
    let path = URL(string: pathArray.joined(separator: "/"))

    //use a guard since the result is an optional
    guard let filePath = path else {
        //if it fails do this stuff:
        return URL(string: "choose how to handle error here")!
    }
    //if it works return the filePath
    return filePath
}

调用函数：

let shinnyNewURLpath = createNewDirPath( ) 


//write data to file using one line in do/catch operation
do {
   try yourDataObject?.write(to: shinnyNewURLpath)
    } 
catch {
       print("catch error",error.localizedDescription)
 }

Answer 3

我使用以下方法创建“Test.txt”文件。 希望对你有帮助。

func createFile() {
    let fileName = "Test"
    let documentDirURL = try! FileManager.default.url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: true)
    let fileURL = documentDirURL.appendingPathComponent(fileName).appendingPathExtension("txt")
    print("File PAth: \(fileURL.path)")
}

Answer 4

func copyandpaste() {
   var path = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)
   let dbpath: NSString = path[0] as NSString
        
   let strdbpath =  dbpath.strings(byAppendingPaths: ["mydb.db"])[0]
   print(strdbpath)
   let fmnager  =  FileManager.default
        
   if !fmnager.fileExists(atPath: strdbpath) {
      let local  = Bundle.main.path(forResource: "mydb", ofType: "db")
      do {
         try fmnager.copyItem(atPath: local!, toPath: strdbpath)
      } catch {
      }
   }        
}