Top "Key-value-observing" questions

Key-value Observing or KVO is a technology for observing changes in object properties.

KVO: How to get old / new values in observeValue(forKeyPath:...) in Swift?

I have created an observer with .Old | .New options. In the handler method I try to fetch before after values, …

swift key-value-observing
observeValueForKeyPath not being called

I have a ViewController creating an instance of a UIView, and then I register an observer with the instance, such …

iphone key-value-observing
How do I properly observe the contentOffset property of my scrollView subclass?

In my iOS app I am observing changes to the contentOffset property of my scrollView subclass. My observer handler looks …

ios uiscrollview key-value-observing cgpoint
key value observers were still registered with it when controller is deallocated

I added an observer in the code and then removed it in dealloc and viewWillDisappear but still i am getting …

ios objective-c memory key-value-observing dealloc
How can I use Key-Value Observing with Smart KeyPaths in Swift 4?

Could you help me how to manage to be notified when the contents of NSArrayController are modified, using Smart KeyPaths? …

swift key-value-observing swift4
Handling AVPlayer stalls

I'm trying to catch a moment when AVPlayer is unable to continue playback in case no more media available (too …

ios objective-c avplayer key-value-observing
KVO addObserver to CoreData object's one-to-many relationship

Hi everyone years reading StackOverflow, now I decided to join. I am struggling to get this resolved: I have a "…

ios objective-c core-data key-value-observing
Swift 4 (BETA 2) KVO crashing, based upon WWDC talk

I am trying to get something very similar to the example in the WWDC 2017 Foundation talk working for KVO observing. …

swift key-value-observing
Crash with removeObserver:forKeyPath: in Foundation

I having some problems with the following crash logs retrieved from the "Crashes" section in Xcode. Only few devices are …

objective-c crash key-value-observing