EODisplayGroupDelegate

(informal protocol)

NSObject

Declared in: EOInterface/EODisplayGroup.h

Category Description

The EODisplayGroupDelegate informal protocol defines methods that an EODisplayGroup can invoke in its delegate. Delegates are not required to provide implementations for all of the methods in the informal protocol. Instead, declare and implement any subset of the methods declared in the informal protocol that you need, and use the EODisplayGroup method setDelegate: method to assign your object as the delegate. A display group can determine if the delegate doesn't implement a delegate method and only attempts to invoke the methods the delegate actually implements.

Fetching objects

- displayGroupShouldFetch:

- displayGroup:didFetchObjects:

- displayGroup:shouldRefetchForInvalidatedAllObjectsNotification:

Inserting, updating, and deleting objects

- displayGroup:shouldInsertObject:atIndex:

- displayGroup:didInsertObject:

- displayGroup:createObjectFailedForDataSource:

- displayGroup:didSetValue:forObject:key:

- displayGroup:shouldDeleteObject:

- displayGroup:didDeleteObject:

Managing the display

- displayGroup:shouldDisplayAlertWithTitle:message:

- displayGroup:shouldRedisplayForChangesInEditingContext:

- displayGroup:displayArrayForObjects:

Managing the selection

- displayGroup:shouldChangeSelectionToIndexes:

- displayGroupDidChangeSelection:

- displayGroupDidChangeSelectedObjects:

Changing the data source

- displayGroupDidChangeDataSource:

displayGroup:createObjectFailedForDataSource:

Invoked from insertObjectAtIndex: to inform the delegate that aDisplayGroup has failed to create a new object for aDataSource. If the delegate doesn't implement this method, the EODisplayGroup instead runs an alert panel to inform the user of the failure.

displayGroupDidChangeDataSource:

Informs the delegate that aDisplayGroup's EODataSource has changed.

displayGroupDidChangeSelectedObjects:

Informs the delegate that aDisplayGroup's set of selected objects has changed, regardless of whether the selection indexes have changed.

displayGroupDidChangeSelection:

Informs the delegate that aDisplayGroup's selection has changed.

displayGroup:didDeleteObject:

Informs the delegate that aDisplayGroup has deleted anObject.

displayGroup:didFetchObjects:

Informs the delegate that aDisplayGroup has fetched objects.

displayGroup:didInsertObject:

Informs the delegate that aDisplayGroup has inserted anObject.

displayGroup:didSetValue:forObject:key:

Informs the delegate that aDisplayGroup has altered a property value of anObject. key identifies the property, and value is its new value.

displayGroup:displayArrayForObjects:

Invoked from updateDisplayedObjects, this method allows the delegate to filter and sort aDisplayGroup's array of objects to limit which ones get displayed. objects contains all of aDisplayGroup's objects. The delegate should filter any objects that shouldn't be shown and sort the remainder, returning a new array containing this group of objects. You can use the added NSArray methods filteredArrayUsingQualifier: and sortedArrayUsingKeyOrderArray: to create the new array.

If the delegate doesn't implement this method, the EODisplayGroup uses its own qualifier and sort ordering to update its displayed objects array.

See also: - sortOrderings, - qualifier, - displayedObjects

displayGroup:shouldChangeSelectionToIndexes:

Allows the delegate to prevent a change in selection by aDisplayGroup. newIndexes is the proposed new selection, an array of NSNumbers . If the delegate returns YES, the selection changes; if the delegate returns NO, the selection remains as it is.

displayGroup:shouldDeleteObject:

Allows the delegate to prevent aDisplayGroup from deleting anObject. If the delegate returns YES, anObject is deleted; if the delegate returns NO, the deletion is abandoned.

displayGroup:shouldDisplayAlertWithTitle:message:

Allows the delegate to prevent aDisplayGroup from displaying an attention panel with title and message. The delegate can return YES to allow aDisplayGroup to display the panel, or NO to prevent it from doing so (perhaps displaying a different attention panel).

displayGroupShouldFetch:

Allows the delegate to prevent aDisplayGroup from fetching. If the delegate returns YES, aDisplayGroup performs the fetch; if the delegate returns NO, aDisplayGroup abandons the fetch.

displayGroup:shouldInsertObject:atIndex:

Allows the delegate to prevent aDisplayGroup from inserting anObject at anIndex. If the delegate returns YES, anObject is inserted; if the delegate returns NO, the insertion is abandoned.

displayGroup:shouldRedisplayForChangesInEditingContext:

Invoked whenever aDisplayGroup receives an EOObjectsChangedInEditingContextNotification, this method allows the delegate to suppress redisplay based on the nature of the change that has occurred. If the delegate returns YES, aDisplayGroup redisplays; if it returns NO, aDisplayGroup doesn't. aNotification supplies the EOEditingContext that has changed, as well as which objects have changed and how. See the EOEditingContext class specification for information on EOObjectsChangedInEditingContextNotification.

See also: - redisplay

displayGroup:shouldRefetchForInvalidatedAllObjectsNotification:

Invoked whenever aDisplayGroup receives an EOInvalidatedAllObjectsInStoreNotification, this method allows the delegate to suppress refetching of the invalidated objects. If the delegate returns YES, aDisplayGroup immediately refetches its objects. If the delegate returns NO, aDisplayGroup doesn't immediately fetch, instead delaying until absolutely necessary. aNotification is an NSNotification. See the EOObjectStore and EOEditingContext class specifications for information on this notification.