CATransition how to clip to bounds of UIView? - iphone

I'm using CATransition to slide subviews of UIView. But the problem is that the CATransition always appears in whole screen. And it looks like a mess because I have another UI elements in window that become overlapped while transitioning. How can I restrict frame of transition by UIView frame? I tried to set clipToBounds of my UIView to YES. Actually it doesn't help.

I'm not really 100% sure about this, but I think you're wrong about CATransition applying to the whole screen. It applies to the view you add the animation to.
The idea is that you apply the transition to the parent of the view you actually want to transition. So say you have the following structure.
UIViewController
view (main view of UIViewController)
view you're transitioning
What you need to do is add a "holding" or "container" view between the main UIViewController view and your actual targeted view, such that it looks like this:
UIViewController
view (main view of UIViewController)
"container" view <-- Apply transition here
view you're transitioning
Apply your transition to the container view and you'll be able to clip it, if you want. If it still goes out of bounds, then try turning on clipsToBounds on the containing view, or the layer's masksToBounds property

Related

Overlaying a UIView on a UIViewController

I have an application with 6 view controllers all working fine and switching between each other. However, I want to overlay one of them with a UIView of graphics (Histogram or Line Chart, etc) which has a transparent background. How do I do this? Or, alternatively how do I switch from a UIViewController to a UIView and back. There is no interaction from the graphic (UIView) so I could use a modalview. What's the best way to achieve either?
Let's say your overlay view is in overlayView variable. Simply put this line in your view controller ...
[self.view addSubview:overlayView];
... and do not forget to set frame or proper autoresizing mask.

UIView Subview Does not autoresize on orientation change

In my iPhone app, I have a view controller with two views (essentially, a front & back view). The front view is the main UIView, and the back view is a secondary UIView which is added as a subview using [self.view addSubview:backView] when showing the back and [backView removeFromSuperview] when hiding it. However, when the orientation changes, I have the following issue: the main UIView (frontView) rotates & all of its elements resize properly, but the secondary/subview UIView (backView) does not rotate & all of its elements do not resize properly. Does anyone have suggestions on how to make the secondary UIView autoresize properly according to the rules I have set in Interface Builder?
In the end, the solution I found was simply to separate my UIViews into separate UIViewControllers, and make sure that any views that I wanted to be able to rotate only had one UIView.
If I understand correctly, at the time of rotation 'backView' has been removed from it's superview, yeah? If so, that's the cause of the problem. The autoresize property determines how the view resizes relative to it's superview. If it doesn't have a superview it won't resize.
Perhaps using [backView setHidden:YES] instead of [backView removeFromSuperview] will be sufficient for your needs.
I had the same problem, here is how I fixed it based on imaginaryboy's
suggestions (thanks!)
Add the backview to the viewcontroller at viewDidLoad and hide it at the same time. Show it when needed, Hide it again. Set the resizing of the backview to UIViewAutoresizingFlexibleWidth in IB (or code I guess, I used IB)
Not that this is the same problem, but I found a similar problem when adding 2 subviews in my application:didFinishLaunchingWithOptions method. Since your reference above is using [self.view addSubview:view], I would understand that to mean that self is not your UIWindow. When adding an additional view controller to your App Delegate window (UIWindow), the second view controller will NOT receive any rotation events and will never rotate. Only the first view controller added to UIWindow will rotate. See:Technical Q&A QA1688 I believe this also affects views added after the first view where the first view is later removed from the superview.
I ended up following the suggestion I read elsewhere to use separate views for each orientation, thereby eliminating the need to worry about resizing behavior. As always, YMMV.
Or; if you want to avoid an additional controller, you can achieve the same effect by setting view.frame in willRotateToInterfaceOrientation:: like so
if(UIInterfaceOrientationIsLandscape([[UIApplication sharedApplication] statusBarOrientation])) ;//set stubborn view.frame for landscape orientation
else ; //set stubborn view.frame for portrait orientation
Although it feels like a hack; it's simple.

preventing a specific view from auto rotating... is that possible?

I have a view based app. Its self.view has several subviews and shouldAutorotateToInterfaceOrientation is returning YES.
When I rotate the device, all views rotate as expected.
Is that possible to prevent a subview from auto rotating even if the view's parent is auto rotating?
Keep in mind that it's the view controller that controls what happens during rotation and not the view itself. You can't stop a subview from rotating by setting a property, or something relatively easy, if its parent view's UIViewController is set to auto rotate. You can, however, have sibling views where one rotates and the other doesn't. It's probably possible to layout your views the way you want but not have the one that shouldn't rotate as a subview of a rotating UIViewController.
You could probably write some code that will reorient a subview so it appears not to rotate when the parent view does rotate, however.

UIScrollView and CALayers

I have a custom UIView that is composed entirely of CALayers.
In the awakeFromNib method it creates and sets all the CALayers into their appropriate positions (CAGradientLayer, several CATextLayers, and a few custom CALayer subclasses). The custom UIView does not override the drawRect: method because there's no drawing done directly into the view (all of the drawing is done in the sublayers).
So I took this view and embedded it in a UIScrollView. The problem? No scroll bars appear and the view does not scroll. The view is clearly larger than the bounds of the scroll view, and instead of allowing me to scroll, it just cuts off at the scroll view bounds.
What could be wrong here?
You have to set the scrollView's contentSize.

Difference between directly setting a controller's view and adding view as a subview

I have just started learning objective-C and the iphone sdk and I have a question that I hope someone can help shed some light on.
What is the difference in the following:
self.view = someView;
and
[self.view addSubView: someView];
Say for example, in a simple app, where we have only one controller and one container view (has a few image subviews).
What is the difference between the two statements? The reason that I'm asking is because I was tinkering around in some sample code and I noticed the view was being initialized with images as subviews like so:
if (self = [super initWithFrame:CGRectZero])
{
//adds some images as subviews here
}
As I understand it the initWithFrame: CGRectZero, creates a frame with size at [0,0,0,0] (essentially invisible).
When I directly set the view with
self.view = someView;
I notice the view actually displays the image. But when I add the view to as a subview of controller's 'default' view, it doesn't. So basically my question is, whats going on behind the scenes? Why is the first method "resizing" the frame and the second one not doing the same thing.
What you see on the screen of your iPhone is almost always a hierarchy of views.
When you look at, say, your inbox in Mail, you're seeing a bunch of views. There's a big containing view.[1] Within that, there's a navigation bar view, a table view, and a toolbar view. Within the navigation bar view, there's a button view on each side and a label view in the middle. Inside the table view, there are a bunch of table cell views, and each of those cells has several label views. The toolbar has five button views. I could go further and talk about the views inside those buttons and so on, but I'm sure you get the idea.
The view above any given view is its superview; the views below it are its subviews. So a table cell view has a table view as its superview and a bunch of label views as its subviews. The top view, the one that has all the other views inside it, is called the root view.
Each view has its own drawing surface. The rectangle formed by that drawing surface is called the frame. The frame of a view is relative to the frame of its containing view. So if one of our table cell's label subviews has its frame at (0,0), that means it will be in the table cell's top left corner, even if the cell is halfway down the screen.
When you're writing a view controller, self.view is that root view I mentioned earlier; all the other views are subviews of that one (or subviews of its subviews, etc.). One of the features of a view controller is that it automatically resizes its self.view to fit the screen. (The available area will be smaller in the middle of a phone call: the status bar is twice as high then, so there's less space for your app. It will also be smaller if your view controller is being managed by a navigation controller or tab bar controller, but that's a different story.) But just because you resize its root view doesn't mean that the root view's subviews will automatically resize. To do that, you need to set their autoresizing mask (a property which tells the view how it should react when its superview changes size):
someView.autoresizingMask = UIViewAutoresizingFlexibleWidth
| UIViewAutoresizingFlexibleHeight;
(There's a graphical way to set up the autoresizing mask in Interface Builder—click the ruler icon in the inspector window and look at the "Autosizing" section.)
Even that's not enough, though, if someView isn't the right size to start with. To do that, adjust its frame before you add it as a subview of self.view:
someView.frame = CGRectMake(
0, // all the way to the left
0, // all the way at the top
self.view.frame.size.width, // same width as the root view
self.view.frame.size.height, // same height too
);
So why would you ever use subviews if you have to do all this twiddling that the root view does for you? Simple: you can only have one root view, but one view is almost never enough for what you need to do. If you really need only one view, of course, you can just set it as the root view and go on your merry way, but chances are, things are more complicated than that.
[1] I'm simplifying a bit here, but that's fine for right now.
When you add a view as a subview, you need to make sure that you're actually adding to an existing view.
self.view = view sets the controller's view. Without this (either in code or done with a XIB) you'll never see anything as the controller has no view to show.
[self.view addSubView: someView] assumes that self.view is already set. If it doesn't, you're adding someview as a subview of nil, and it will never get seen.
Basically, think of self.view as the big container, and all the subviews are just pieces inside of it. If you don't need any subviews, setting self.view to a UIImageView or UIWebView is fine. If you do need subviews, you'll need a big, empty container view in which to put them.
In your case, I'm betting self.view is never set, and you're adding your image views to nil.
Setting the view controller "view" property only changes the view it is managing.
Adding a view as a subview of another view, actually adds the subview underneath the other view.
They are very different things, as one adjusts a view controller and the other alters a view hierarchy.
As a guess, the reason you didn't see anything the first way was the frame for the subview you were adding was CGRectZero (0 in size).