Get memory usage

I'm trying to get the memory usage of the entire system.

// referance: https://www.jb51.cc/iOS/590624.html
public func memsize() -> UInt64 {
    var taskInfo = mach_task_basic_info()
    var count = UInt32(MemoryLayout<mach_task_basic_info>.size)
    let kerr: kern_return_t = withUnsafeMutablePointer(to: &taskInfo) {
        $0.withMemoryRebound(to: integer_t.self,capacity: 1) {
            task_info(mach_task_self_,task_flavor_t(MACH_TASK_BASIC_INFO),$0,&count)
        }
    }
 
    if kerr == KERN_SUCCESS {
        return taskInfo.resident_size
    }
    return 0
}

not working, apparently. When my system uses 15 GB it shows it's below 1 GB.

Do anyone have other ways to get memory usage of the device (better macOS)