What are the fundamental differences between set and didSet?

Question

I understand that one is a setter and the other is a property observer. My question is how do they differ in behavior and when would you use one over the other. Don\'t they

Answer 1

One more thing. :)

set {} is calling when you initialise value, but not disSet {}

var x : Int = 0 {
  set {
    print(x)
  }
}
...
x = 1

produce "0" and "1" output.

But didSet not so.

var x : Int = 0 {
  didSet {
    print(x)
  }
}
...
x = 1

have not call before you change value. Only "1" result will be printed, not "0" and "1"

It can be as useful, so bug source.