Swift Combine: What does objectWillChange do?

What will happen in sink { } block?


objectWillChange.sink is not showing you the latest value

Sample App
TextField and Button
What would viewModel.text print?
What would happen?

Strange Result

This prints out the previous value.
Instead of “value changed to Hello World”, it’s just “Click to change value”!

Set up ObservableObject without @Published

Set up ObservableObject without @Published


  1. ObservableObject gives you objectWillChange property.
  2. You can access objectWillChange and subscribe.
  3. objectWillChange is called before actually changing the value!



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KD Knowledge Diet

KD Knowledge Diet


Software Engineer, Mobile Developer living in Seoul. I hate people using difficult words. Why not using simple words? Keep It Simple Stupid!