How to initialise an OutputStream with a Url? - ios

Question

I try to create an OutputStream to an app group folder, which is created as follows:
func createProjectDirectoryPath(path:String) -> String
{
let containerURL = FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: "group.xyz")
let logsPath = containerURL!.appendingPathComponent(path)
NSLog("12345- folder path: %#", logsPath.path)
do {
try FileManager.default.createDirectory(atPath: logsPath.path, withIntermediateDirectories: true, attributes: nil)
} catch let error as NSError {
NSLog("12345- Unable to create directory %#", error.debugDescription)
}
return logsPath.path
}
This function gives me a path like this
/private/var/mobile/Containers/Shared/AppGroup/40215F20-4713-4E23-87EF-1E21CCFB45DF/pcapFiles
This folder exists, because the line FileManager.default.fileExists(path) returns true. The next step is to append a generated filename to the path, which I am doing here
let urlToFile = URL(string: createProjectDirectoryPath(path: "pcapFiles").appending("/\(filename)"))
which gives me the correct new path
/private/var/mobile/Containers/Shared/AppGroup/40215F20-4713-4E23-87EF-1E21CCFB45DF/pcapFiles/39CC2DB4-A6D9-412E-BAAF-2FAA4AD70B22.pcap
If I call this line, ostream is always nil
let ostream = OutputStream(url: urlToFile!, append: false)
Do I miss something? The OutputStream should create the file on this path, but for unknown reason, it is not possible.
PS: AppGroup is enabled in Capabilities and in developers console.

Answer 1

Your createProjectDirectoryPath() function returns a file path,
therefore you must use URL(fileURLWithPath:) to convert that to an
URL. Alternatively, modify your function to return an URL instead:
func createProjectDirectoryPath(path:String) -> URL? {
let containerURL = FileManager.default.containerURL(forSecurityApplicationGroupIdentifier: "group.xyz")
let logsURL = containerURL!.appendingPathComponent(path)
do {
try FileManager.default.createDirectory(at: logsURL, withIntermediateDirectories: true)
} catch let error as NSError {
NSLog("Unable to create directory %#", error.debugDescription)
return nil
}
return logsURL
}
In addition, you have to call open() on all Stream objects before
they can be used, this will also create the file if it did not exist
before:
guard let logsURL = createProjectDirectoryPath(path: "pcapFiles") else {
fatalError("Cannot create directory")
}
let urlToFile = logsURL.appendingPathComponent(filename)
guard let ostream = OutputStream(url: urlToFile, append: false) else {
fatalError("Cannot open file")
}
ostream.open()