What is Key-Value-Coding and Key-Value-Observing in Objective C?

Question

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 Docum

Answer 1

Key Value Coding is simply accessing a property of an object through a string instead of the literal syntax.

// Here is a new instance of an object
Foo *foo = [[Foo alloc] init];
// Accessing a property called someValue with literal syntax:
[foo someValue];
// Accessing the same property with dot notation
foo.someValue;
// Accessing the same property with Key-Value coding:
[foo valueForKey:@"someValue"];

The power of KVC is that you can specify any arbitrary string at runtime (obviously this could be very dangerous too).