Detect if video is still being written to

Question

Created Oct ’18

Replies 17

Boosts 0

Views 4.2k

Participants 4

So, I'm trying to write a function to detect if a video file is currently being recorded to. The purpose is if it is, than you can't delete the file or rename it. Here's what I have:

public func fileSizeDetection(url: URL) -> Int{
    
    let tempFile = URL(string:(try! FileManager.default.url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: false).absoluteString) + "tempFile")
    
    let keys : Set<URLResourceKey> = [URLResourceKey.fileSizeKey]
    
    
    do{
        try FileManager.default.copyItem(at: url, to: tempFile!)
        usleep(5000)
    }
    catch{
        print (error.localizedDescription)
    }
    
    let tempValues = try! tempFile!.resourceValues(forKeys: keys)
    let tempSize = tempValues.fileSize!
    let permValues = try! url.resourceValues(forKeys: keys)
    let permSize = permValues.fileSize!
    let difference = permSize - tempSize
    
    do{
        try FileManager.default.removeItem(at: tempFile!)
    }
    catch{
        print (error.localizedDescription)
    }
    
    return difference
}

So, I it starts by passing the URL to test. Than it creates a temporary copy of the file which is supposed to be a snapshot of it. Than it sleeps for a second, and compares the current file size to the copied file size. If there's no difference than it's not a recording in progress. Finally it deletes the temp copy.

The issue I'm having, is that tempFile and the original URL are the same size! I tried to increase usleep, but it still doesn't work. Can anyone please tell me what I'm doing wrong!

Boost

Answer 1

DTS Engineer OP

Apple

Oct ’18

NSFileCoordinator
does block the main thread.

Cool. If that works then you should be able to do the work async using

-coordinateAccessWithIntents:queue:byAccessor:

(or one of the higher-level wrappers around that, like

-coordinateReadingItemAtURL:options:error:byAccessor:

).

Share and Enjoy
—
Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware

let myEmail = "eskimo" + "1" + "@apple.com"

0

Answer 2

Mr. Bruce Wayne OP

Jan ’19

Accepted Answer

It ended up being very simple. I looked at all of the options you guys showed me, but in the end my original function just needed to be modified a little.

func detectIfRecording(url: URL) -> Int {
        
        let keys: Set<URLResourceKey> = [URLResourceKey.fileSizeKey]
        let values1 = try! url.resourceValues(forKeys: keys)
        let bytes1 = Int64.init((values1.fileSize!))
        usleep(250000)
        let values2 = try! URL(fileURLWithPath: url.path).resourceValues(forKeys: keys)
        let bytes2 = Int64.init((values2.fileSize!))
        if bytes2 > bytes1{            
            return 1
        }else{
            return 0
        }
}

I only need to check the newest video, not every single one.

0