Swift: UnsafeMutablePointer.deinitialize fatal error with negative count when appending to array

Question

The code below generates this error (appending to exporters):

fatal error: UnsafeMutablePointer.deinitialize with negative count

Answer 1

I had a similar error, the issue was caused by multiple threads modifying the array at the same time. Wrapping the append calls in a serial dispatch queue solved it for me.

    let serialQueue = DispatchQueue(label: "myqueue")

    serialQueue.sync {
        exporters.append(exporter)
    }