Add alpha to view VS Add alpha to UIColor

Question

Is writing this :

view.backgroundColor = UIColor.white.withAlphaComponent(0.9)

Equivalent to this:

view.backgroundColor = UIColor.white
view.alpha = 0.9

if not, what is the difference ?

Answer 1

Simple explanation

Case 1:

viewMain.backgroundColor = UIColor.white.withAlphaComponent(0.9)

it will reduce the alpha color of the particular view i.e. viewMain here.

Case 2:

viewMain.alpha = 0.5

It will reduce the opacity of the view and if viewMain have multiple views then all views alpha will be reduced that amount.

Example :

Let be your view hierarchy is like this

viewMain
     -> view1
         -> view2

Now from Case1, alpha of ViewMain will be reduced only. But in Case 2 alpha of viewMain, view1, view2 will be reduced.

If you have no hierarchy, then both are same.

If you have view hierarchy, then it makes effect like below