How to get the file content?

Question

I have Obj-C code that looks like this

NSURL * url = [[NSBundle mainBundle] URLForResource:@"MyFile" withExtension:@"txt"];
NSError * err = nil;
NSString * string = [NSString stringWithContentsOfURL:url encoding:NSUTF8StringEncoding error:&err];

This code is working properly. I need to convert it to Swift one, so I did it like this

func getContentOfUrl(by fileName: String) -> String? {
    var result: String?
    guard let pathToFile = Bundle.main.path(forResource: fileName, ofType: "txt")
        else {
            return nil
        }
      
      do {
        result = try String(contentsOf: URL(string: pathToFile)!, encoding: String.Encoding.utf8)
      }
      catch let err{
      }
      
      return result
    }

And I get an error in the catch block

Attempt to get content of URL FAILED, error: Error Domain=NSCocoaErrorDomain Code=256 "The file “MyFile.txt” couldn't be opened." UserInfo={NSURL=/private/var/containers/Bundle/Application/63FB01-F11-411-B93-6578DEF57B/MyApp.app/MyFile.txt}

what am I doing wrong?

Answer 1

This works for me.

func getFile(named: String) -> String? {
    guard let url = Bundle.main.url(forResource: named, withExtension: "txt") else { return nil }
    return try? String(contentsOf: url, encoding: .utf8)
}

If it doesn't you need to make sure that the resource file actually exists.

You can test little functions like this in a playground. Add the file you want to use to the Resources folder in the playground. I did this with a file name "MyText.txt" and this worked fine.

Answer 2

Apart from the fact that you should use a method that returns a URL instead of a file path as already mentioned is that you are using the wrong init method when creating the URL yourself. URL(string:) expects a string in a url format (file://...) but you have a local path so instead you should use URL(fileURLWithPath:) . So this will make your existing code work

result = try String(contentsOf: URL(fileURLWithPath: pathToFile), encoding: .utf8)

Or use the URL directly

func content(of fileName: String) -> String? {
    Bundle.main.url(forResource: fileName, withExtension: "txt")
        .flatMap { try? String.init(contentsOf: $0, encoding: .utf8) }
}