Static CKErrorRetryAfterKey 

pub unsafe static CKErrorRetryAfterKey: &'static NSString

Available on crate feature CKError only.

On some errors, the userInfo dictionary may contain a NSNumber instance that specifies the period of time in seconds after which the client may retry the request. For example, this key will be on CKErrorServiceUnavailable,``CKErrorRequestRateLimited,and other errors for which the recommended resolution is to retry after a delay.

See also Apple’s documentation