src/Helpers/Request/FormatConverter.php
public function convertDateIcuToPhp($pattern, $type = 'date', $locale = null)
    {
        return $this->proxyWithLanguage(__FUNCTION__, [$pattern, $type, $locale]);
    }
public function convertDateIcuToPhp($pattern, $type = 'date', $locale = null)
    {
        return $this->proxyWithLanguage(__FUNCTION__, [$pattern, $type, $locale]);
    }
Converts a date format pattern from [ICU format][] to [php date() function format][].

The conversion is limited to date patterns that do not use escaped characters.
Patterns like `d 'of' MMMM yyyy` which will result in a date like `1 of December 2014` may not be converted correctly
because of the use of escaped characters.

Pattern constructs that are not supported by the PHP format will be removed.

[php date() function format]: http://php.net/manual/en/function.date.php
[ICU format]: http://userguide.icu-project.org/formatparse/datetime#TOC-Date-Time-Format-Syntax

@param string $pattern date format pattern in ICU format.
@param string $type 'date', 'time', or 'datetime'.
@param string $locale the locale to use for converting ICU short patterns `short`, `medium`, `long` and `full`.
If not given, `Yii::$app->language` will be used.
@return string The converted date format pattern.
@see \Reaction\Helpers\FormatConverter::convertDateIcuToPhp()