Question

in my program there is a MainView and during the program user can add some subView.
for handling them i want to know which subView now are showing on top level.

NOTE: I do not remove subViews unless the user wants. and the subviews are in different sizes and may have overlap or not.

Answer 1

subviews

The receiver’s immediate subviews. (read-only)

@property(nonatomic, readonly, copy) NSArray *subviews

You can use this property to retrieve the subviews associated with
your custom view hierarchies. The order of the subviews in the array
reflects their visible order on the screen, with the view at index 0
being the back-most view.

From UIView Class Reference