Menu
Can someone explain in simple terms what is Key-Value-Coding and Key-Value-Observing? Please don't provide links to Apple Developer's reference Document. I have gone through them. I expect an explanation in very simple terms.
916
KVO and KVC or Key-Value Observing and Key-Value Coding are mechanisms originally built and provided by Objective-C that allows us to locate and interact with the underlying properties of a class that inherits NSObject at runtime.
About Key-Value Coding. Key-value coding is a mechanism enabled by the NSKeyValueCoding informal protocol that objects adopt to provide indirect access to their properties. When an object is key-value coding compliant, its properties are addressable via string parameters through a concise, uniform messaging interface.
Key-value observing is a Cocoa programming pattern you use to notify objects about changes to properties of other objects. It's useful for communicating changes between logically separated parts of your app—such as between models and views. You can only use key-value observing with classes that inherit from NSObject .
Key-value observing provides a mechanism that allows objects to be notified of changes to specific properties of other objects. It is particularly useful for communication between model and controller layers in an application.
Key-Value-Coding (KVC) means accessing a property or value using a string.
id someValue = [myObject valueForKeyPath:@"foo.bar.baz"]; Which could be the same as:
id someValue = [[[myObject foo] bar] baz]; Key-Value-Observing (KVO) allows you to observe changes to a property or value.
To observe a property using KVO you would identify to property with a string; i.e., using KVC. Therefore, the observable object must be KVC compliant.
[myObject addObserver:self forKeyPath:@"foo.bar.baz" options:0 context:NULL]; If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
