iOS 9 read file permission

Question

In iOS 9+ I get a nil on any attempt to read from file. The file in this case is a image file path.
using

NSData(contentsOfFile: stringpath, options: NSD         


        

Answer 1

I encountered this error because I was attempting to access multiple files in the same block. The fix that worked for me was changing the code structure such that each file url was obtained, then read from, before attempting to get the next file url.

Answer 2

In your Application, you don't have permission to access the file of /var/mobile/Media/DCIM/100APPLE/IMG_0048.JPG, because of Sandboxing.

So, whatever you do, you can't initialize NSData or UIImage with the file path. But you can access the file of /var/mobile/Media/DCIM/100APPLE/xxx.mov with AVURLAsset. In my application, I extracted the data rather than URL from gallery by Photos kit and initialized UIImage with the data.

PHImageManager.default().requestImageData(
    for: assetObject!, options: options,
    resultHandler: {
        data, _, _, _ in
        if data != nil {
            self.assetUrl = movieMaker.createMovieFrom(imageData: data!, duration: Int(CXPreparetValue.imageDuration))
        }
})

it works for me! If you have other opinions, please tell me.

Answer 3

In my case, the file permissions were too restrictive, so I couldn't read the file.

Adding read+write permissions to the file before accessing it solved it.

do {
    // Retrieve any existing attributes
    var attrs = try FileManager.default.attributesOfItem(atPath: stringpath)
    let existing = (attrs as NSDictionary).filePosixPermissions()
    // Set the read+write value in the attributes dict
    attrs[.posixPermissions] = existing | 0b110000000
    // Update attributes
    try FileManager.default.setAttributes(attrs, ofItemAtPath: stringpath)

    // Read data from file
    let data = try Data(contentsOf: URL(fileURLWithPath: stringpath, isDirectory: false), options: .uncached)
    print("success: \(data.count)")
} catch {
    print(error)
}

That works if you're in a folder with enough permissions, as you can change the files permissions even if you didn't had read permission on the file previously. This solution was applied at https://github.com/ZipArchive/ZipArchive/issues/293.

Answer 4

You are most likely getting this error, because iOS apps only have access to files within its sandbox. See Apple documentation on file systems for details.