Swift implementation of function for measuring application launch time. Call it from start or end didFinishLaunchingWithOptions.

LaunchTimeMeasurer.swift

import UIKit

class LaunchTimeMeasurer {
    private let pid = ProcessInfo().processIdentifier
    private var currentTime = timeval(tv_sec: 0, tv_usec: 0)
    private var bootTime = timeval()
    private var size = MemoryLayout<kinfo_proc>.stride
    private var mib: [Int32]
    
    init() {
        mib = [CTL_KERN, KERN_PROC, KERN_PROC_PID, pid]
    }
    
    func processLaunchTime() -> Double {
        sysctl(&mib, u_int(mib.count), &bootTime, &size, nil, 0)
        gettimeofday(&currentTime, nil)
        
        return toSeconds(time: currentTime) - toSeconds(time: bootTime)
    }
    
    private func toSeconds(time: timeval) -> Double {
        let microsecondsInSecond = 1000000.0
        return Double(time.tv_sec) + Double(time.tv_usec) / microsecondsInSecond
    }
}

I was able to figure out what was wrong, and it might help @RagulChandra too. sysctl takes a kinfo_proc, not a timeval. Using a timeval will still return the correct value, but causes memory corruption later on in your app's life cycle.

Here are the modifications that should be made to avoid memory corruption:

...
private var kp = kinfo_proc()  // kp instead of bootTime
...

func processLaunchTime() -> Double {
  sysctl(&mib, u_int(mib.count), &kp, &size, nil, 0)
  gettimeofday(&currentTime, nil)

  let bootTime = kp.kp_proc.p_un.__p_starttime  // this is a timeval struct

  return toSeconds(time: currentTime) - toSeconds(time: bootTime)
}