EOActionAssociation
- Inherits from:
- EOAssociation : EODelayedObserver (EOControl) : NSObject
- Conforms to:
- NSCoding
- (EOAssociation)
- EOObserving (EODelayedObserver)
- NSObject (NSObject)
Declared in:
- EOInterface/EOActionAssociation.h
Class Description
An EOActionAssociation object allows you to set up an interface object, such as a button, to send a message to the objects selected in the association's display group when the interface object is acted on.
| Usable With |
| Any control object (NSControl, NSActionCell, and their subclasses) |
| Aspects | |
| action | Bound to a key that names the method to invoke on the
selected objects. If the argument aspect
isn't bound, the method must take no arguments. If the argument aspect
is bound, then the method must take exactly one argument. |
| argument | An object attribute or relationship of the selected object,
passed as an argument to the action method. (Usually bound to a
different EODisplayGroup than the one bound to action.) |
| enabled | A boolean attribute of the selected object, which determines whether the display object is enabled. |
| Object Keys Taken | |
| target | On receiving an action message from the display object, an EOActionAssocation sends its action to the selected objects. |
Examples
Suppose you have an application that manages member accounts, each of which has a restriction on the outstanding balance allowed. You want a user to be able to increase the restriction limit by selecting one or more members and then clicking a button. To do this, you define a boostRestrictions method in the Member class that increases the limit by 20%. In Interface Builder, control-drag a connection from the button to the Member display group. Select EOActionAssociation in the Connections inspector, and bind the association's action aspect to the "boostRestrictions" key.
In another scenario, one EODisplayGroup shows Members, while another shows video tapes available for rent. Here, you want a user to be able to select a member, select a video tape, and then click a Rent button that checks the selected tape out to the selected member. To do this, define a rentVideoTape: method in the Member class that takes a VideoTape as an argument and handles the accounting involved in a video rental. Then, in Interface Builder, control-drag a connection from the button to the Members display group. Select EOActionAssociation in the Connections inspector, and bind the association's action aspect to Member's rentVideoTape: action. Similarly, control-drag a connection from the button to the VideoTape display group. Select EOActionAssociation in the Connections inspector, and bind the association's argument aspect to the VideoTape display group. Now, when the user selects a Member, selects a VideoTape, and clicks the button, the selected Member is sent a rentVideoTape: message with the selected VideoTape.
Instance Methods
action:
- (void)action:(id)sender
Invoked when the receiver's display
object is acted upon. Sends the method identified by the receiver's action aspect
(with an argument, if the argument aspect
is bound) to the selected objects.