Use the current date as BuildNumber on Xcode projects build with Bitrise.

getBuildNumberByDate.go

package main

import (
	"fmt"
	"os"
	"os/exec"
	"time"
)

// RunEnvmanAdd ...
func RunEnvmanAdd(key, value string) error {
	args := []string{"add", "--key", key, "--value", value}
	return RunCommand("envman", args...)
}

// RunCommand ...
func RunCommand(name string, args ...string) error {
	cmd := exec.Command(name, args...)
	cmd.Stdin = os.Stdin
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	return cmd.Run()
}

func main() {
	now := time.Now()

	// iso8601 time format (timezone: RFC3339Nano)
	// ex: 2015-07-07T16:34:05.51843664+02:00
	timeString := fmt.Sprintf("%v", now.Format("20060102"))
fmt.Println("Going to store BUILD_NUMBER_DATETIME:", timeString)
	if err := RunEnvmanAdd("BUILD_NUMBER_DATETIME", timeString); err != nil {
		fmt.Println("Failed to store BUILD_NUMBER_DATETIME:", err)
		os.Exit(1)
	}
}