ACF plugin support

[athlan]

It seems to be useful to support ACF Plugin fields.

Proposed scope:

• Multi checkbox value. Use all joined, first, last.
• Radio button
• Date picker and Date time picker: date with default format, date with custom format, extract part of date (day, month, year, hour, minute, second).
• Post object (postname, post id)

Consider as an extension to the plugin.

References:

• Plugin shows serialized value (ACF Checkbox) #26

[athlan]

Before complete:

• Support for single metadata generation hook #28
• Support for field usage attributes in permalink definition #29

[athlan]

https://github.com/athlan/wordpress-custom-fields-permalink-plugin/wiki/ACF-plugin-support