apple.foundation.enums

Class NSKeyValueObservingOptions

java.lang.Object

apple.foundation.enums.NSKeyValueObservingOptions

public final class NSKeyValueObservingOptions
extends java.lang.Object

Options for use with -addObserver:forKeyPath:options:context: and -addObserver:toObjectsAtIndexes:forKeyPath:options:context:.

Field Summary

Fields

Modifier and Type	Field and Description
static long	Initial Whether a notification should be sent to the observer immediately, before the observer registration method even returns.
static long	New Whether the change dictionaries sent in notifications should contain NSKeyValueChangeNewKey and NSKeyValueChangeOldKey entries, respectively.
static long	Old Whether the change dictionaries sent in notifications should contain NSKeyValueChangeNewKey and NSKeyValueChangeOldKey entries, respectively.
static long	Prior Whether separate notifications should be sent to the observer before and after each change, instead of a single notification after the change.

Method Summary

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

New

public static final long New

Whether the change dictionaries sent in notifications should contain NSKeyValueChangeNewKey and NSKeyValueChangeOldKey entries, respectively.

See Also:

Constant Field Values

Old

public static final long Old

Whether the change dictionaries sent in notifications should contain NSKeyValueChangeNewKey and NSKeyValueChangeOldKey entries, respectively.

See Also:

Constant Field Values

Initial

public static final long Initial

Whether a notification should be sent to the observer immediately, before the observer registration method even returns. The change dictionary in the notification will always contain an NSKeyValueChangeNewKey entry if NSKeyValueObservingOptionNew is also specified but will never contain an NSKeyValueChangeOldKey entry. (In an initial notification the current value of the observed property may be old, but it's new to the observer.) You can use this option instead of explicitly invoking, at the same time, code that is also invoked by the observer's -observeValueForKeyPath:ofObject:change:context: method. When this option is used with -addObserver:toObjectsAtIndexes:forKeyPath:options:context: a notification will be sent for each indexed object to which the observer is being added.

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Constant Field Values

Prior

public static final long Prior

Whether separate notifications should be sent to the observer before and after each change, instead of a single notification after the change. The change dictionary in a notification sent before a change always contains an NSKeyValueChangeNotificationIsPriorKey entry whose value is [NSNumber numberWithBool:YES], but never contains an NSKeyValueChangeNewKey entry. You can use this option when the observer's own KVO-compliance requires it to invoke one of the -willChange... methods for one of its own properties, and the value of that property depends on the value of the observed object's property. (In that situation it's too late to easily invoke -willChange... properly in response to receiving an -observeValueForKeyPath:ofObject:change:context: message after the change.)

When this option is specified, the change dictionary in a notification sent after a change contains the same entries that it would contain if this option were not specified, except for ordered unique to-many relationships represented by NSOrderedSets. For those, for NSKeyValueChangeInsertion and NSKeyValueChangeReplacement changes, the change dictionary for a will-change notification contains an NSKeyValueChangeIndexesKey (and NSKeyValueChangeOldKey in the case of Replacement where the NSKeyValueObservingOptionOld option was specified at registration time) which give the indexes (and objects) which *may* be changed by the operation. The second notification, after the change, contains entries reporting what did actually change. For NSKeyValueChangeRemoval changes, removals by index are precise.

See Also:

Constant Field Values