Save file in document directory in swift 3?

问题

I am saving files in a document directory in swift 3 with this code:

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

But as you can see, I am not using filemanager to get document directory path as filemanager gives only URL not string.

Questions:

• How to get string from file manager?
• Is there any chance of crash in my code?

回答1:

Please think the other way round.

URL is the recommended way to handle file paths because it contains all convenience methods for appending and deleting path components and extensions – rather than String which Apple has removed those methods from.

You are discouraged from concatenating paths like path = path + name. It's error-prone because you are responsible for all slash path separators.

Further you don't need to create a file with FileManager. Data has a method to write data to disk.

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 = UIImageJPEGRepresentation(image, 0.5) {
        try imageData.write(to: fileURL)
        return true
    }
} catch {
    print(error)
}
return false

回答2:

following the above example given by vadian the only line you need to save a (Data)file in Document Directory is:

try imageData.write(to: fileURL)

Getting the file path is the interesting part

ex: create the file path

 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
}

call the function:

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)
 }

回答3:

I use the following method for creating "Test.txt" file. Hope it helps you.

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)")
}

回答4:

func copyandpast() {

    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{

        }



    }


}

来源：https://stackoverflow.com/questions/44646186/save-file-in-document-directory-in-swift-3