PSPDFAnnotationPlaceholderState

NS_CLOSED_ENUM(NSInteger, PSPDFAnnotationPlaceholderState) {
    /**
     The placeholder is still dormant.

     Its `progress` and `error` properties are both `nil`.
     */
    PSPDFAnnotationPlaceholderStateIdle,

    /**
     The placeholder has become active.

     Its `progress` property is populated with an object that can be used to display the progress of
     replacing the placeholder with actual content. The placeholder’s `error` property is `nil`.
     */
    PSPDFAnnotationPlaceholderStateProgressing,

    /**
     The process of replacing the placeholder with actual content has failed.

     The `progress` property is `nil`. The `error` property holds an object detailing why/in which
     way replacing the placeholder with actual content failed.
     */
    PSPDFAnnotationPlaceholderStateFailed,

    /**
     The process of replacing the placeholder with actual content has been cancelled.
     */
    PSPDFAnnotationPlaceholderStateCancelled,

    /**
     The actual content has become available.

     The placeholder has become obsolete, so neither its `progress`, not its `error` property matter
     anymore.
     */
    PSPDFAnnotationPlaceholderStateCompleted,
}