Key-value Observing or KVO is a technology for observing changes in object properties.
Questions tagged [key-value-observing]
1201 questions
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NSMutableAttributedString KVO Not Firing Notification
I'm having a dilemma that I can't seem to solve. I've applied some KVO through a binding to a property on a model, however, because I'm not assigning through dot notation the KVO doesn't get fired. Instead, I'm appending like so:
[[self…
Kieran Senior
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app crashes when [self setValue:forKey:] is called
.h File
...
@property(nonatomic,readwrite)NSNumber *isConnectionWithServerEstablished;
when ever i setValue for isConnectionWithServerEstablished the app crashes
CRASH POINT:
[self setValue:Number…
Yadnesh
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removeObserver fails with Core Data
I am observing a core data value with KVO, but when I remove the observer, I get the message:
Cannot remove an observer for the key path "flightname.value" from because it is not registered as an observer.
Code below called two times. First time…
János
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removeObserver for KVO with UINavigationController
I'm trying to use Storyboards and to reduce coupling between my classes using KVC. Like the Contacts app, I have editable fields that push new view controllers where you can edit data. Before I show one of my detailViewControllers, I do things…
Crystal
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Make NSDocument "edited" when a binded control changes
I have an array of NSDictionaries and a NSDictionary iVar (*selectedDictionary) that points to one of the array's objects. *selectedDictionary points to a different object every time the user selects a different row in a NSTableView. Several GUI…
Vassilis
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KVO notifications of app delegate stop unexpectedly
I have a key in my app delegate that I listen for changes using the following code:
[self addObserver:self forKeyPath:@"myKey" options:0 context:nil];
After some time though, the app delegate stops responding to changes to myKey. Why does this…
Matt
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Cocoa Touch Question. Using KVO in a touch sequence context
I would like to use KVO in the following context:
1) In touchesBegan:withEvent: I alloc/init an instance of an object that I then observe via KVO
My intent is to observe varous behaviors of the object throughout its life time.
2) In…
dugla
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CoreData register global observer for all objects and keys
how can / should I register a KVO observer for all entities and keys, regardless of their type?
The purpose of this is to monitor changes to objects and mark them as modified, so that I can provide sync functionality through a JSON API with a web…
George Penn.
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Automatically update NSOutlineView upon model changes without NSTreeController
If I changed my NSOutlineView from using bindings and an NSTreeController to having a data source and a delegate, how would I automatically update the NSOutlineView, if my model tree changes? Should I observe the childNodes property of every single…
DrummerB
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Is it possible to animate changes to data represented in CorePlot?
I'm looking to use CorePlot to show a bunch of data from an API, I'd like to observe changes so the graph can change dynamically. For the best experience, I'm thinking that the data should be animated.
I understand that it's entirely up to me to…
Roderic Campbell
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how .addObservers and observevalue method works in iOS Swift 5
I am using tableView.addObserver and observeValue method for my Swift project to give tableView Height according to its content. its working completely fine but I don't know how. can someone please explain me with this
here's my code.
…
aditya vaghela
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Why doesn't KVO observer get called on a sub object?
With the following Swift playground, why does the observer inside view never get called?
import Foundation
@objc class Person: NSObject {
@objc dynamic var name = "Taylor Swift"
}
let taylor = Person()
taylor.observe(\Person.name, options:…
lewis
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About KVO different behavior in iOS10 and iOS11 without `removeObserver:forKeyPath:`
Once I forgot to call "removeObserver:forKeyPath:" when I was using KVO. On iOS10 simulator, the simulator crashed. But on iOS11 simulator, everything was normal. There's no memory leak and no crash.
I'm confused why not calling…
Johnson
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About forKeyPath
I am following this tutorial to get to know KVC.
stated in that tutorial the following
[someObject.someProperty setText:@"This is a text"];
Using KVC:
[self setValue:@"this is a text"
forKeyPath:@"someObject.someProperty.text"]
my questions…
Amrmsmb
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SAPUI5 change detection mechanism
Hello I am writing a research paper on change detection(between model and view) mechanisms across JavaScript frameworks - Virtual DOM, Key-Value Observation, Dirty Checking(Angular JS). I am curious what kind of change detection mechanism is behind…
GeForce RTX 4090
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