make allow for subviews to interact with buttons in iPhone or iPod Touch

A line of code below can allow for subviews to interact with buttons.

[contentView setUserInteractionEnabled:YES];

I made a sample app with a button and compiled and run at simulator.
But button did not respond to button press.

I spent many hours to get button response.
Just a line of code make it possible.

A button in my app respond very well to avery button press.
I got a peace of mind.