(iPhone SDK 7) UIScrollView subview touch problem

Question

New here, in fact new to the SDK but getting on well with it (plenty of previous coding experience to draw on). However, I've been hitting my head against a brick wall with UIScrollView and it making subviews, e.g. UIImageViews, no longer be touchable. When I move the image views outside the scroll view it's fine, so I know they're working and the touchesBegan:withEvent is processing as it should do.
Here's what I'm doing in the initWithFrame:
scroller = [[UIScrollView alloc] initWithFrame:CGRectMake(0,0,320,400)];
scroller.scrollEnabled = YES;
CGSize sz;
sz.width = 320;
sz.height = 800;
scroller.contentSize = sz;
scroller.tag = 400;
scroller.userInteractionEnabled = YES;
scroller.delaysContentTouches = YES;
scroller.canCancelContentTouches = NO;
[self addSubview:scroller];
(I've tried all different combinations of delaysContentTouches and canCancelContentTouches just to see if they made a difference, originally I hadn't got either in there. But they don't seem to alter anything)
And then the image views:
buttonPlay = [[UIImageView alloc] initWithFrame:CGRectMake(20,320,40,40)];
buttonPlay.image = [UIImage imageNamed:@"blah.jpg"];
buttonPlay.userInteractionEnabled = YES;
buttonPlay.tag = 100;
[scroller addSubview:buttonPlay];
buttonSettings = [[UIImageView alloc] initWithFrame:CGRectMake(80,320,40,40)];
buttonSettings.image = [UIImage imageNamed:@"blah.jpg"];
buttonSettings.userInteractionEnabled = YES;
buttonSettings.tag = 101;
[scroller addSubview:buttonSettings];
Basically no touch events are being generated anywhere I click within the scroll view and I'm at a loss to work out why.
Not sure if it's related either but I can't get a UILabel to respond to a touch either, even though I've enabled userInteractionEnabled for it - even trying a simple project I can't get a UILabel to generate a touch event at all.
Any help on the above scroll view issue would be appreciated as it's driving me nuts!
Cheers

Answer 1

UIScrollView must not pass these events up the responder chain. I'm not sure if this is intended behavior, but it seems like it might be (if so the docs should be updated). I took my test code and verified:
1. scroller's nextResponder points the UIView of the ViewController.
2. That UIView has a nextResponder pointing to the ViewController
This is what you would expect from the docs on the UIResponder Chain. However, it relies on each UIView subclass to pass the event up the responder chain +if it isn't handled fully+. UIScrollView must be making the assumption that "the buck stops here". Hence your touchesBegan: in your viewController never gets the message.
Further, a little more testing with this at the end of viewDidLoad:
BOOL status1 = [scroller canResignFirstResponder];
BOOL status2 = [scroller resignFirstResponder];
BOOL status3 = [self.view becomeFirstResponder];
showed me:
status1 = NO
status2 = NO
status3 = NO
I'd say UIScrollView likes the power it wields .