iOS AutoLayout不适用于嵌入ScrollView的视图

Question

I'd like to embed views into each other (in the current case into a scrollview to allow displaying taller content than the screen's size) and use iOS 6.0's AutoLayout feature in order to avoid constant calculation of content size's.

I have the following ViewController's view, containing a UIScrollView:

I'd like to display my ChildVC's view in this scrollview:

Please notice that the label is multiline and contains a 'lot of' text, also auto-layout constraints are defined (escpecially with a greater-than-or-equal to the height property).

I create the childVC and add it to the main VC's view via the following code:

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.

    childVC = [[ChildVC alloc] initWithNibName:@"ChildVC" bundle:nil];    

    self.myScrollView.translatesAutoresizingMaskIntoConstraints = NO;
    childVC.view.translatesAutoresizingMaskIntoConstraints = NO;

    [self.myScrollView addSubview:childVC.view];

    NSDictionary *viewsDictionary = @{ @"subView" : childVC.view};

    NSString* constr = [NSString stringWithFormat:@"|-0-[subView(%f)]-0-|", self.myScrollView.frame.size.width];    
    [self.myScrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:constr options:0 metrics: 0 views:viewsDictionary]];

    [self.myScrollView addConstraints:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|-0-[subView]-(>=0)-|" options:0 metrics: 0 views:viewsDictionary]];
}

The constraints for the content-view (which I guess will be the childVC's view) are the only stuff set up in code, because I only want a vertical scrollbar, I want the child-view's content to (horizontally) shrink to be displayed in the scrollviewer.

And my output is this:

The UI is displayed, shrinked but my label does not resize vertically therefore it does not display the whole text :(

I tried to set up translatesAutoresizingMaskIntoConstraints to the label here and there without any success.

I'd appreciate any help because I'm struggling with this for days now :/

Answer 1

Personally, I think those constraints and the auto layout feature just don't always work exactly as we want them to. (Especially on different screen sizes).

So I normally add a few line of code in the viewDidLoad method to move certain objects around by a few pixels. You can also change sizes and so on.

Literally a simple movement like this does the trick without the user noticing any animations:

object_name.frame = CGRectOffset(object_name.frame, 0, -40.0f);