Package apple.foundation.enums

Class 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 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.
        See Also:
        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