UIViewController viewDidLoad

Question

I've got a new project and I can work with iOS 5+ feature, so I choose to use both AutoLayout and UIViewController childControllers capabilities.

The screen I'm trying to create is simple : 1. The top area has lot of "complex" controls. 2. The bottom area is a tableview to visualize results.

What I want

I want the controls area to take all necessary place (ie the place I gave into Interface Builder). The TableView will shrink as needed.

Problem

When loaded from a XIB the UIViewController.view frame has ALWAYS a size of 0x568. I was expected 0x200 (if 200 was the size I configured in Interface Builder).

What works : with AutoLayout

I created a XIB with all my element. I did the outlet on the "root view" and I did outlet and all views containers.

Then in my viewDidLoad method I added the containers and configured constraints.

-(void) setupConstraints
{
    NSMutableArray *constraints = [NSMutableArray arrayWithCapacity:1];

    // Views dictionary.
    UIView *topView = self.topView;
    UIView *table   = self.tableTracks;
    NSDictionary *views = NSDictionaryOfVariableBindings(topView, table);

    // Views metrics.
    NSNumber *topViewHeight = [NSNumber numberWithFloat:self.topView.frame.size.height];
    NSDictionary *metrics = NSDictionaryOfVariableBindings(topViewHeight);

    // Pin the topView to the top edge of the container.
    [constraints addObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[topView(==topViewHeight)][table]|" options:0 metrics:metrics views:views]];

    // Pin the topView edges to both sides of the container.
    [constraints addObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[topView]|" options:0 metrics:nil views:views]];

    // Pin the table edges to both sides of the container.
    [constraints addObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[table]|" options:0 metrics:nil views:views]];

    [self.view addConstraints:constraints];
}

With this, I can simple resize the topView view with Interface Builder and the TableView will be resized as needed (no compression resistance, I don't care if we can't see the table).

What DO NOT works : with AutoLayout and ChildControllers

Then for simplicity I choose to use ChildControllers (lot of outlet required to perform custom UIFont setup, too bad XCode can't handle them yet!). I made the following modifications :

1. Created HomeTopViewController classes + XIB. Created HomeTableViewController classes + XIB.
2. Copied all views from the origin to the correct XIB. Add the UIViewController references + wired the outlets.
3. The root container of HomeTopViewController is configured to 200px height.
4. Wired my containers to the view outlet of my childs controllers.

Then I updated my setup code to the following :

-(void) _addChildViewControllersAndSetupConstraints {
    // Get required metrics variables
    NSNumber *topViewHeight = [NSNumber numberWithFloat:self.topViewController.view.frame.size.height];

    CFShow(self.topViewController.view);
    // log is : <UIView: 0xa209c20; frame = (0 0; 320 568); autoresize = W+H; layer = <CALayer: 0xa2097e0>>
    NSLog(@"self.topViewController.view.frame.size.height = %f", self.topViewController.view.frame.size.height);


    // Informs controllers the ADD operation started
    [self addChildViewController:self.topViewController];
    [self addChildViewController:self.tableViewController];

    // Add view to the view's hierarchy
    self.topViewController.view.translatesAutoresizingMaskIntoConstraints = NO;
    self.tableViewController.view.translatesAutoresizingMaskIntoConstraints = NO;

    [self.view addSubview:self.topViewController.view];
    [self.view addSubview:self.tableViewController.view];


    // Setup constraints
    NSMutableArray *constraints = [NSMutableArray arrayWithCapacity:1];

    // Views dictionary
    UIView *topView = self.topViewController.view;
    UIView *table   = self.tableViewController.view;

    NSDictionary *views = NSDictionaryOfVariableBindings(topView, table);

    // Views metrics dictionary
    NSDictionary *metrics = NSDictionaryOfVariableBindings(topViewHeight);

    // Pin the topView to the top edge of the container.
    [constraints addObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"V:|[topView(==topViewHeight)][table]|" options:0 metrics:metrics views:views]];

    // Pin the topView edges to both sides of the container.
    [constraints addObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[topView]|" options:0 metrics:nil views:views]];

    // Pin the table edges to both sides of the container.
    [constraints addObjectsFromArray:[NSLayoutConstraint constraintsWithVisualFormat:@"H:|[table]|" options:0 metrics:nil views:views]];

    // Adds constraints
    [self.view addConstraints:constraints];


    // Informs controllers the ADD operation ended
    [self.topViewController didMoveToParentViewController:self];
    [self.tableViewController didMoveToParentViewController:self];
}

Problem

No matter how I size the UIView container in HomeTopViewController the line CFShow(self.topViewController.view); will always give me frame = (0 0; 320 568) when I expected 200px.

I did configure the layout size to "Freeform" or "None".

What I want to avoid as much as possible

I would hate having to create other outlets then View on HomeTopViewController and HomeTableViewController and storing the initial frame / height into a UIViewController property.

Questions

1. At load time, are all controller.view.frame property sized on the screen ? (be it 3,5 or 4 inches)
2. How can I solve this without hardcoding the size somewhere // creating additionnal outlets ?

Answer 1

This would be easier if you used a storyboard. You can add container views to you main controller's view and size them how you like, and you automatically get view controllers embedded in these container views that are set to the correct size. These container views (next to the regular UIView in the object list) are only available from a storyboard, not xibs. This will require almost no code, and you probably won't have to add any constraints manually.