I'm developing an app using a fork of LeavesViewController that changes to a two-page orientation when the device turns to landscape.
When using the Leaves controller alone, everything works fine.
When using the Leaves controller inside the view of my main UIViewController, it never gets any of the device rotation messages (however my main UIViewController does).
What can I do to make the Leaves controller reaceive the device rotation messages?
Thanks.
You're not supposed to nest UIViewControllers like that. In practice you can, but they're not managed by UIKit so you lose the functions that are usually called by the framework (viewWillAppear: and friends, I think).
You can forward the rotation methods yourself.
Related
I am trying to write an App for Apple tv4 (tvos). When my App starts, the view controller does receive touchesBegan events, as it should.
Without going into too many details, the App creates, moves, and deletes sub-views to respond to the user's interactions.
After a while, the view controller does not receive touchesBegan any more (this is the strange error that I am trying to debug).
Since I think the problem has something to do with the responder chain, I have made the following two experiments:
If I let the view controller override and return true from canBecomeFirstResponder, then the problem still occurs, but it occurs much less frequently.
If I do not override that function and instead check who is the first respnder, then I find that the App has no first responder, even before the strange error occurs. That is to say, the App has no first responder even when it is working properly!
Questions: What can prevent touchesBegan from being invoked? Is it related to the responder change? If so, please explain 2 above.
How exactly are you supposed to "touch" a view rendered on a non-touch screen enabled TV?
You're not.. tvOS doesn't work like iOS in the way that you cannot detect touches because there is no touch screen enabled input device supported on an Apple TV.
Instead, you use the UIFocusEngine to handle interactions with content presented within your view hierarchy.
Check out "Controlling the User Interface with the Apple TV Remote" from Apple's Developer Library for more information.
I created a new project "Single View Application" and designed the mainView with Storyboard. My main view contains a UIButton that opens the camera, the camera scans barcode and automatically goes to a website. Now I created a webView programmatically so that website can open and also created a UIButton inside the webView. Now I want that UIButton to act as home botton and return to mainview. I am unable to do that, please help.
ViewController.m code: http://cl.ly/FKj8
My storyboard looks like:
You really should look into the View Controller Programming Guide -- by switching around the contents of a single view controller, you're making a lot of extra work for yourself with little benefit. By using multiple view controllers when you want to have different "screens" in your app, you can take advantage of storyboarding for easier development, and you automatically get better memory management (read: less potential for crashes), too.
However, to more directly answer your question... if you're putting the WebView into the view hierarchy with [self.view addSubview:webView], you can remove it with [webView removeFromSuperview]. (This means you'll have to keep a reference to the WebView around so you can refer to it when you want to dismiss it.)
I also noticed in the code you posted to cl.ly an unrelated method -deviceModel which uses uname() to get device information. This is a bad idea, for two reasons:
uname() isn't guaranteed to do something useful on an iOS device (even if it currently does). Use the UIDevice class instead if you need this kind of info, or...
Generally, you don't want to test for the device name to enable functionality in your app; instead, you should test for the capabilities you need. (For example, if you look for a device name starting with "iPhone 4" to test for a Retina display, you'll miss the 4th-generation iPod touch, and the iPhone-5-or-whatever-they-call-what's-next. Instead, use the UIScreen class.)
Short version
If I'm writing my own custom split view controller, what do I need to do to make the child view controllers work as expected?
For instance: to send viewWillAppear: and so on.
Long version
Background
A while back I answered the following question:
Switch between UIViewControllers using UISegmentedControl
With the following answer:
The right way to do it is to have the controller handling the UISegmentedControl add the views of the controllers as subviews.
[self.view addSubview:controller.view];
It's your responsibility to send viewWillAppear: and so on.
However, tc. pointed out that this is not as trivial as it sounds:
No. View controllers are not meant to be used like that - controller will miss out on a lot of the UIViewController magic that's taken for granted (namely -view{Will,Did}{Appear,Disappear}: and -shouldRotateToViewOritentation:).
By "magic", I'm referring to everything UIKit does behind the scenes. You also forgot -parentViewController (which is important for things like modal view controllers). Additionally, somewhere in the depths of UIKit, it automatically calls -viewSomethingSomething: for you, so you might get -viewDidDisappear: twice! (I can't remember the exact details, but there's another user reporting that all you need to do is call -viewWillAppear: and the other three methods happen automatically.) The key issue is that Apple doesn't document the "magic" or how it changes between OS updates.
Since then I've been thinking that one should compile a guide for what needs to be present in the parent view controller in order for the child view controllers to work as expected. Apple's documentation doesn't cover this and Google didn't help much either, so now I'm hoping to find this knowledge within the stackoverflow community.
I've written several controllers like this and they all seem to work, but I can't help but wonder if I'm missing out on important view controller magic.
I think the best solution is "don't do that". Instead of hoping that you can duplicate all of UIViewController's behavior without being rejected for using private API calls why not create non-UIViewController controller objects to manage your subviews? A "controller" is not necessarily a UIViewController.
At a minimum you would need to override or mix in replacement getters for parentViewController, splitViewController, navigationController, tabBarController, and interfaceOrientation (and probably also modalViewController). For each property you would need to make sure that any private setter called by UIKit still works as expected and any changes to those values made by modifying UIViewController ivars directly are also correctly reflected in your implementations.
You're also going to need to figure out how UIKit determines which UIViewController is currently active and should receive view controller lifecycle methods because you need to make sure that these are sent to your container view controller and not only to one of it's children.
You will also have to hope that you haven't just constructed a situation which isn't supported by any of Apple's view controller classes. For example will any of them break if they have a parentViewController but their navigationController, tabBarController, and splitViewController are all nil?
Finally you'll need to keep up with any changes to these private implementation details with every iOS release.
I'm trying to implement auto-rotation in my application that is basically UINavigationController with lots of UIViewControllers that get pushed onto it.
I've copy-pasted this in my first UIViewController (that gets pushed into UINavigationController):
- (BOOL)shouldAutorotateToInterfaceOrientation:
(UIInterfaceOrientation)interfaceOrientation {
return YES;
}
Everything worked fine... However, if I paste in that code into second UIViewController (that first one pushes on top after some button click) - autorotation won't work. shouldAutorotateToInterfaceOrientation gets called when UIViewController is first initialized, but after it is visible and I rotate device - nothing happens.
So result is: first view gets rotated well - portrait/landscape... but after I click button and get into second view I remain stuck into that portrait or landscape, whatever was active.
I tried subclassing UINavigationController and setting shouldAutorotateToInterfaceOrientation there, but that also doesn't work.
What am I doing wrong?
There's a bug in the API that doesn't cause it to work for the second view. I solved it originally using setOrientation, but that's a private API and thus not a reasonable solution. I haven't released any new versions of the application while I try to figure out alternatives (and I don't think having customers upgrade to OS 4.0 is a solution). I'm thinking I'll need to manually keep track of the orientation and rotate my views manually to counteract the effects of the wrong rotation.
You need to implement this method in all views in the hierarchy
What are single-state and two-stage animation for rotating an iPhone window?
This is the "error" message I get in the Debugger Console (nothing crashes):
Using two-stage rotation animation. To use the smoother single-stage animation, this application must remove two-stage method implementations.
I was working through the book "Beginning iPhone Development: Exploring the iPhone SDK" by Apress (Dave Mark, Jeff LaMarche) on the Swap Project.
Everything is explained in the UIViewController Class Reference. Especially check out the View Rotation section near the top.
From the reference:
Handling View Rotations
By default, the UIViewController class
displays views in portrait mode only.
To support additional orientations,
you must override the
shouldAutorotateToInterfaceOrientation:
method and return YES for any
orientations your subclass supports.
If the autoresizing properties of your
views are configured correctly, that
may be all you have to do. However,
the UIViewController class provides
additional hooks for you to implement
additional behaviors as needed.
To temporarily turn off features that
are not needed or might otherwise
cause problems during the orientation
change, you can override the
willRotateToInterfaceOrientation:duration:
method and perform the needed actions
there. You can then override the
didRotateFromInterfaceOrientation:
method and use it to reenable those
features once the orientation change
is complete.
If you want to perform custom
animations during an orientation
change, you can do so in one of two
ways. Orientation changes used to
occur in two steps, with notifications
occurring at the beginning, middle,
and end points of the rotation.
However, in iPhone OS 3.0, support was
added for performing orientation
changes in one step. Using a one-step
orientation change tends to be faster
than the older two-step process and is
generally recommended for any new
code.
To add animations for a one-step
orientation change, override the
willAnimateRotationToInterfaceOrientation:duration:
method and perform your animations
there. To use the older two-step
method, override one or both of the
willAnimateFirstHalfOfRotationToInterfaceOrientation:duration:
and
willAnimateSecondHalfOfRotationFromInterfaceOrientation:duration:
methods to configure your animations
before each step. You must choose only
one technique and override just the
methods associated with that
technique. If you override either
method associated with the two-step
technique, the view controller uses
that technique by default.
I have found the culprit in my case to be the UIImagePickerController (I also do not override any rotation animation):
[self presentModalViewController:imagePicker animated:YES];
Replacing imagePicker with a generic UIViewController doesn't generate any warnings.
I changed from willAnimateFirstHalfOfRotationToInterfaceOrientation:duration: method to willAnimateRotationToInterfaceOrientation:duration: method and warning gone.
Thanks.
Ed Marty's answer is the correct one. The reason it will happen if you are not overriding any of the rotation animation is probably that you reply "YES" to shouldAutorotate.. for some view. If you do not implement rotation at all, then you should just not override the shouldAutorotate.. method. If you do override that method, then just override the single step rotation method as well and pass it along to the super.
If you're using iOS 4 and you're getting this warning, I found a way to get rid of it. In your info.plist, there is an item called "Supported interface orientations." Select which orientations your application supports and two-stage warnings will go away when bringing up the imagePicker.
#plumiscles answer didn't quite work for me - there was no item called 'Supported Interface Orientations', probably b/c it is an old project. But you can get the same effect by editing the .plist file directly and adding this:
<key>UIInterfaceOrientation</key>
<string>UIInterfaceOrientationPortrait</string>
Need to add UIImagePickerController as a subview to solve this error
[self.view addSubview:picker.view];
[self presentModalViewController:picker animated:NO];
I've had this issue after creating a tabbarcontroller with no view controllers inside (no tabs), this warning disappeared once I attached at least one view controller to it.
I wasn't over riding any of those two-step functions, but I was calling my own function when I received orientationChanged notifications, and I had this line of code in it. Commenting it out got rid of the warning and allowed the auto rotate to work properly. Auto rotate still worked with this line of code until iOS 4.2, then it broke completely. Spent a lot of time looking for why the built in autoRotate stopped working in 4.2. Maybe this will help someone else.
Commented out this line to make it work:
[[UIApplication sharedApplication] setStatusBarOrientation:currentOrientation animated:YES];
I've delete from plist "Supported interface orientations" row and warning disappears.
I just had the same problem. In my case was a silly mistake that I'm putting here just in case anyone else falls into that same issue.
In my tabbed app I remove one of the original ViewControllers and added a new one with Storyboard to create a "Settings" section.
This new VC had to be a table view VC and even I designed, compiled and run it without a problem, when I changed the orientation of the app I kept getting this “Using two-stage rotation animation” error.
My problem was that I forgot to change in the original .h file interface "UIViewController" for "UITableViewController".
Once this was done I changed on the Storyboard identity badge the class from the general value to my SettingsViewController and that was the end of it.
I hope it can help someone else. It took me a while to get to bottom of this.
Cheers,