interop.Reference returns undefined value

Hi everyone,

I need your help to understand why the vmStatRef.value.free_count in the below code returns undefine value.

I am using NativeScript 8.1. The platform is iOS.

  "devDependencies": {
    "@nativescript/android": "~8.1.1",
    "@nativescript/core": "~8.1.4",
    "@nativescript/ios": "~8.1.0",
    "@nativescript/types": "~8.1.1",
    "@nativescript/webpack": "^3.0.0",
    "prompt": "^1.2.0",
    "rimraf": "^3.0.2",
    "semver": "^7.3.5",
    "ts-node": "^10.4.0",
    "ts-patch": "^1.4.4",
    "tslint": "^6.1.3",
    "typescript": "~4.4.4"
  }

The git repository is https://github.com/DeepakArora76/nativescript-dna-deviceinfo

Here is a 64-bit implementation

  static freeMemory(): number {
    const KERN_SUCCESS = 0;
    const HOST_VM_INFO = 2;
    const hostSize = new interop.Reference(interop.sizeof(vm_statistics64)/interop.sizeof(interop.types.int64));
    const hostPort = mach_host_self();

    const pageSize = new interop.Reference(0);
    host_page_size(hostPort, pageSize);

    const vmStat = interop.alloc(interop.sizeof(vm_statistics64));

    let freeMem = -1;
    if (host_statistics64(hostPort, HOST_VM_INFO, vmStat, hostSize) === KERN_SUCCESS) {
      const vmStatRef = new interop.Reference<vm_statistics64>(vm_statistics64, vmStat);
      freeMem = vmStatRef.value.free_count * pageSize.value;
    }
    return freeMem;
  }

I also tried vm_statistics instead of vm_statistics64 and that too failed as well!

32-bit implementation

  static freeMemory(): number {
    const KERN_SUCCESS = 0;
    const HOST_VM_INFO = 2;
    const hostSize = new interop.Reference(interop.sizeof(vm_statistics)/interop.sizeof(interop.types.int32));
    const hostPort = mach_host_self();

    const pageSize = new interop.Reference(0);
    host_page_size(hostPort, pageSize);

    const vmStat = interop.alloc(interop.sizeof(vm_statistics));

    let freeMem = -1;
    if (host_statistics(hostPort, HOST_VM_INFO, vmStat, hostSize) === KERN_SUCCESS) {
      const vmStatRef = new interop.Reference<vm_statistics>(vm_statistics, vmStat);
      freeMem = vmStatRef.value.free_count * pageSize.value;
    }
    return freeMem;
  }

Beginne damit, das gemeldete Verhalten rund um interop.Reference, vm_statistics64, vm_statistics, host_statistics64 und host_statistics auf NativeScript iOS 8.1 zu reproduzieren. Vergleiche die allokierten vmStat-Daten mit dem über vmStatRef.value.free_count bereitgestellten Wert. Als abgeschlossen gilt die Aufgabe, wenn identifiziert wurde, warum das zurückgegebene Feld undefined ist, und ein funktionierendes Ergebnis für den freien Speicher auf der gemeldeten Plattform bestätigt wurde.