key-value-observing Questions
5
Solved
I need to track the update in a variable of struct type.
Is it possible to add an observer on struct variable in Swift?
Example:
struct MyCustomStruct {
var error:Error?
var someVar:String?
}
...
Thebaid asked 17/1, 2019 at 8:29
4
I'm trying to use RxSwift for binding in MVVM.
I have a Enum:
enum Color : Int {
case Red = 0, Green
}
and class for test
class Test : NSObject {
var color: Color = .Red
dynamic var test: St...
Reeve asked 16/3, 2016 at 9:31
11
Solved
If you tell an Objective-C object to removeObservers: for a key path and that key path has not been registered, it cracks a sad, like:
Cannot remove an observer <observerObject> for the key ...
Grave asked 17/10, 2009 at 15:0
4
I'm getting the following in my output window when running a project:
An -observeValueForKeyPath:ofObject:change:context: message was received but not handled.
Key path: connection.messageQueue
Ob...
Domeniga asked 4/9, 2012 at 19:52
1
Solved
I've been looking for a way to trigger a method when the number of displays connected to a mac changes. I know I can get the value of NSScreen.screens.count, but I need to find a way to create a no...
Riannon asked 24/11, 2021 at 21:41
2
Solved
I am having trouble with the new observe API in Swift 4.
player = AVPlayer()
player?.observe(\.currentItem.status, options: [.new], changeHandler: { [weak self] (player, newValue) in
if let statu...
Gwenora asked 24/9, 2018 at 8:40
4
Solved
I have looked around all over for an answer to this and I have tried to implement it, but nothing is working. Basically, I need to be able to observe changes in a VC view's subviews array. If an ex...
Peachy asked 6/11, 2014 at 18:35
5
Solved
I'm rewriting parts of an app, and found this code:
fileprivate let defaults = UserDefaults.standard
func storeValue(_ value: AnyObject, forKey key:String) {
defaults.set(value, forKey: key)
de...
Robillard asked 14/5, 2017 at 11:13
6
Solved
I have some idea of which to use when but the exact usage is still not clear to me. Can someone explain with example?
Ahimsa asked 23/10, 2011 at 7:6
3
Solved
Is KVO on a computed property possible in Swift?
var width = 0
var height = 0
private var area : Double {
get {
return with * height
}
}
self.addOberser(self, forKeyPath: "area", ......
Wou...
Westing asked 11/4, 2016 at 17:37
4
Solved
There is the observationInfo method which returns information of bindings of an object. I have looked around but i do not know how to get the information from the dictionary. Can any one lead me in...
Slacken asked 11/7, 2013 at 16:40
2
Solved
If I store an observer like this:
let observer: NSKeyValueObservation = foo.observe(\.value, options: [.new]) { (foo, change) in
print(change.newValue)
}
How do I remove/disable/cleanup observe...
Paratrooper asked 5/10, 2017 at 17:33
4
Solved
I have a box that the user is able to pan around. For that, I add an observer to check if it's center has changed:
self.boxView!.addObserver(self, forKeyPath: "center", options: .old, context: &am...
Amyl asked 11/9, 2018 at 12:34
3
Solved
Apples documentation alludes to it, but how do you set up key-value observation for the loadedTimeRanges property of AVPlayerItem? That property is an NSArray that doesn't change, so you can't just...
Babul asked 25/1, 2012 at 0:27
3
I use the following code to add KVO on object.
[self.model addObserver:self
forKeyPath:@"userName"
options:NSKeyValueObservingOptionNew | NSKeyValueObservingOptionOld
context:nil];
Now I wan...
Seductive asked 27/1, 2013 at 0:45
2
Solved
I have a custom NSManagedObject subclass, say, Person. I also have a UIView registered with -addObserver:forKeyPath:options:context: to observe various properties of a Person, some of which are per...
Resuscitator asked 16/9, 2010 at 15:32
4
Solved
I have a class with a static var where the current online connection status is stored. I want to observe the value of ConnectionManager.online through other classes. I wanted to do this with KVO, b...
Theotokos asked 6/7, 2016 at 22:34
2
Solved
Why can't I observe the editing property of an instance of UITableViewController?
I'm using the following code:
[self addObserver:self
forKeyPath:@"editing"
options:(NSKeyValueObservi...
Typehigh asked 28/9, 2010 at 21:9
2
Solved
I am happy with the use of Key Value Observing (KVO), and how to register to receive notifications of property change:
[account addObserver:inspector
forKeyPath:@"openingBalance"
options:NSKeyVa...
Kostroma asked 21/11, 2012 at 10:40
3
Solved
Is it possible to add an observer to get notified if any of the monitored object properties is modified? For example:
@interface OtherObject : NSObject
@property (nonatomic) MyObject* myObject;
...
Onshore asked 1/10, 2012 at 12:33
9
Solved
I want to watch for changes in a UIView's frame, bounds or center property. How can I use Key-Value Observing to achieve this?
Togoland asked 2/2, 2011 at 12:8
3
I having some problems with the following crash logs retrieved from the "Crashes" section in Xcode. Only few devices are affected by this crash report.
I have analyzed the problem but I g...
Matchwood asked 11/5, 2015 at 10:17
11
Solved
If so, are there any key differences that weren't otherwise present when using key-value observation in Objective-C?
Paeon asked 7/6, 2014 at 0:5
4
Solved
I'm trying to observering collectionView.contentSize like this :
func startObserveCollectionView() {
collectionView.addObserver(self, forKeyPath: "contentSize", options: NSKeyValueObservingOption...
Topless asked 15/7, 2015 at 4:14
5
Solved
I am relatively new to KVO, so there is a good chance that I am violating some fundamental rule. I am using Core Data.
My app crashes with the following message: And what I can't understand is why...
Audile asked 8/11, 2010 at 0:46
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