I have the following piece of code to add a QLPreviewController subview
{
QLPreviewController *preview = [[QLPreviewController alloc] init];
preview.delegate = self;
preview.dataSource = self;
[self addChildViewController:preview];
[self.view addSubview:preview.view];
[preview didMoveToParentViewController:self];
self.previewController = preview;
}
-(NSInteger) numberOfPreviewItemsInPreviewController:(QLPreviewController *)controller
{
return 1;
}
-(id) previewController:(QLPreviewController *)previewController previewItemAtIndex:(NSInteger)index
{
return self.url;
}
self.url is an NSURL that is located in NSTemporaryDirectory - file://localhost//.../blah.pdf
My issue is that when my laptop is connected to the internet, the document shows up as a subview, but when my laptop is not connected, numberOfPreviewItemsInPreviewController & previewItemAtIndex do not get called.
I've tried a vanilla program with a simple view controller, and it seemed to work fine. (My app is more complex than that).
When I try presenting the document as a modal view, it seems to work irrespective of whether or not the simulator is connected to the internet.
[self presentViewController:preview animated:NO completion:nil]; --> works consistently.
I need to get the subview working for online & offline modes, it would be great if someone could help!
You might be encountering strange behaviour because the QLPreviewController's view is not designed to be embedded in another view. From the QLPreviewController class reference overview:
To display a Quick Look preview controller you have two options: You can push it into view using a UINavigationController object, or can present it modally, full screen, using the presentModalViewController:animated: method of its parent class, UIViewController.
Having said that, you could try:
Forcing the QLPreviewController to (re)display its contents. Try adding [self.previewController reloadData]; to the end of your first method. This should force the data source method(s) to fire.
Forcing the view to "refresh" it's subviews: [self.view setNeedsLayout] (which may in fact force a reloadData like the first option).
Good luck!
Related
My app allows users to import video and perform a few other actions like send an email. When I call the standard code to present these view controllers (example below), the result is that scrollable elements appear underneath the status bar, which is hideous. My own View Controllers do not suffer from this glitch. The problem seems to occur in iOS 7 and 8.
I see many related questions, but most of them address dealing with the status bar in your own view controllers, and I've already done that. My question is about dealing with view controllers I get from the OS.
Any idea what we might be doing (e.g. in storyboard) to cause this? Did I forget or miss an obvious step? It's very ugly and distracting and a fix would be fantastic. I don't see this in any other app.
UIImagePickerController *mediaUI = [[UIImagePickerController alloc] init];
mediaUI.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
// Displays saved movies from the Camera Roll album.
mediaUI.mediaTypes = #[(__bridge NSString *)kUTTypeMovie];
mediaUI.allowsEditing = YES;
mediaUI.delegate = self; //with or without this, the glitch appears
[self presentViewController:mediaUI animated:YES completion:nil];
Here's what it looks like:
The only solution I could find was to remove the status bar. This might be possible via davidisdk's answer to this question, but I did it by subclassing UIImagePicker (and a few other classes) like this:
#interface NoStatusBarImagePickerController : UIImagePickerController
#end
#implementation NoStatusBarImagePickerController
- (BOOL)prefersStatusBarHidden {
return YES;
}
- (UIViewController *)childViewControllerForStatusBarHidden {
return nil;
}
#end
As part of my updating my apps to replace the deprecated presentModalViewController with presentViewController, I did some testing.
What I found was disturbing. Whereas presentModalViewController always works and there is no question about it working, I have found the presentViewController method often will not display my VC at all. There is no animation and it never shows up.
My loadView are called without problems, but the actual view does not appear.
So here is what I am doing:
User taps a button in my main view controller.
In the callback for that tap, I create a new view controller and display it as shown above.
The VC never appears (it is an intermittent problem though) but because this VC begins playing some audio, I know that its loadView was called, which looks like as follows.
My button-pressed callback is as follows:
- (void) buttonTapped: (id) sender {
VC *vc = [[VC alloc] init];
[self presentViewController: vc animated:YES completion: nil];
[vc release];
}
Here is my loadview in the VC class:
- (void) loadView {
UIView *v = [UIView new];
self.view = v;
[v release];
... create and addsubview various buttons etc here ...
}
Thanks.
Make sure the controller that calls the function has its view currently displayed (or is a parent to the one currently displayed) and it should work.
I am trying to get a popup effect and want to design the popup view in another view controller so i can use the xib to do it.
When i used the presentViewController or pushViewController and set the background to transparent, i end up seeing the Window's background color.
I tried this code to add subview to the navigation controller's view so that i can have the Info view cover the entire screen with a transparent background. I also have tab bar to cover up as well.
InfoVC *vc = [[InfoVC alloc] initWithNibName:#"InfoVC" bundle:nil];
[self.navigationController.view addSubview:vc.view];
My problem is inside my InfoVC when i try to dismiss it, the app will crash with some EXC_BAD_ACCESS message:
[self.view removeFromSuperview];
EDIT:
I found a way to stop it crashing but setting the InfoVC as a property in the MainVC. I think the reason for crash is when i call "self.view" in the action inside the InfoVC, it doesn't know that self is the InfoVC inside MainVC.
InfoVC *vc = [[InfoVC alloc] initWithNibName:#"InfoVC" bundle:nil];
[self.navigationController.view addSubview:vc.view];
No no no no. Never never do that.
There is an elaborate dance that you must traverse in order to put a view controller's view inside another view controller's view (or remove it afterwards) if it doesn't come with built-in facilities for doing this (the way a UISplitViewController does, or the way a navigation controller manages the views of the view controllers that are pushed and popped within it).
Read up on customer container controllers. One of the examples from my book is here:
https://github.com/mattneub/Programming-iOS-Book-Examples/blob/master/ch19p556containerController/p476containerController/ViewController.m
Shouldn't you be using the following to remove the view from its superview?
[vc.view removeFromSuperview];
You can never have a UIView remove it's subviews, the subviews themselves must remove themselves from it's superview. You can easily loop through subviews and have them removed like so
for (UIView *view in vc.view.subviews) {
[view removeFromSuperview];
}
Docs for reference:
http://developer.apple.com/library/ios/#documentation/uikit/reference/uiview_class/uiview/uiview.html
After a "modally" presented view controller has appeared the views under the now presented view controller will be removed; this saves memory, and eases rendering. In your case, though, you also end up seeing the window behind the "modally" presented view.
The natural, and seemingly logical, next step is to simply take one view controller's view and cram it into another. However, as you have discovered, this is problematic. With the newly inserted view safely retained by the view hierarchy it is safe, but the new view controller is not so lucky, it is quickly deallocated. So when this new view tries to contact its controller you will get an EXC_BAD_ACCESS and crash. One workaround, again as you have found, is to simply have the original view controller keep a strong reference to the new view controller. And this can work... badly. There's still a good chance you will get an UIViewControllerHierarchyInconsistencyException.
Of course if you simply want to add a small view you create in IB you don't need to use a view controller as the "File's Owner" and there are many examples of creating an instance of a view from a xib file.
The more interesting question here is, "How would/does apple do it?" Apple consistently says that a view controller is the correct controller for an encapsulated unit of work. For example, their TWTweetComposeViewController, you present it, and it seems to float. How?
The first way of accomplishing this that comes to my mind is to have a clear background that isn't clear. That is, create an image of the screen before the presented view controller appears and set that as the background before the presenting view is removed. So for example(Explanation to follow):
QuickSheetViewController.xib
QuickSheetViewController.h
#import <UIKit/UIKit.h>
#interface QuickSheetViewController : UIViewController
- (IBAction)dismissButtonPressed:(id)sender;
#end
QuickSheetViewController.m
#import "QuickSheetViewController.h"
#import <QuartzCore/QuartzCore.h>
#implementation QuickSheetViewController {
UIImage *_backgroundImage;
}
-(void)renderAndSaveBackgroundImageFromVC:(UIViewController *)vc{
UIGraphicsBeginImageContext(vc.view.bounds.size);
[vc.view.layer renderInContext:UIGraphicsGetCurrentContext()];
_backgroundImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
}
-(void)viewWillAppear:(BOOL)animated{
[super viewWillAppear:animated];
// save an image of the current view, and set our background to clear so we can see the slide-in.
[self renderAndSaveBackgroundImageFromVC:self.presentingViewController];
self.view.backgroundColor = [UIColor clearColor];
}
-(void)viewDidAppear:(BOOL)animated{
[super viewDidAppear:animated];
// Time to use our saved background image.
self.view.backgroundColor = [UIColor colorWithPatternImage:_backgroundImage];
}
-(void)viewWillDisappear:(BOOL)animated{
[super viewWillDisappear:animated];
// Set our background to clear so we can see the slide-out.
self.view.backgroundColor = [UIColor clearColor];
}
- (IBAction)dismissButtonPressed:(id)sender {
[self dismissViewControllerAnimated:YES completion:nil];
}
- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation{
return (interfaceOrientation == UIInterfaceOrientationPortrait);
}
#end
The majority of this example hinges upon the renderAndSaveBackgroundImageFromVC: method. In which, we create a graphics context render the view we are about to cover into it, and then create a UIImage to later (in viewDidAppear) use as a background.
Now simply use it like:
QuickSheetViewController *newVC = [[QuickSheetViewController alloc] initWithNibName:nil bundle:nil];
[self presentViewController:newVC animated:YES completion:nil];
You will see through the background just long enough for the animation to happen, then we use our saved image to hide the removal of the presenting view.
I have an app that is loading a overlay controller (shows camera so I can scan). It works great on the iPhone and it works great on the iPad after I call it a second time. Let me explain.
I have a UIButtonBarItem that loads a view controller modally. There are several controls on in the controller, most buttons (defined using a nib). If I load the controller (by responding to the UIButtonBarItem action) on an iPhone, it loads and all the buttons work fine, every time.
But... if I load the same view controller using an UIPopoverController, none of the buttons will respond the first time I load it. So, I touch the screen somewhere outside of the controller and dismiss the controller. Then, I touch the same action button again and now when the controller loads, all the controls in the the view controller work great. REALLY WEIRD!
[POSSIBLE HINT]
The buttons were placed all over the place in weird positions when I loaded it the first time. Each subsequent call had the buttons showing in the right places. I got this to work by disabling "Autoresize subviews" in the nib. The buttons are now in the right places but they still won't respond when I load this popover the first time.
Here's the code I'm using to respond to the UIButtonBarItem.
-(void)launchOverlayController:(id)sender
{
if([pickerControllerPopover isPopoverVisible])
{
[pickerControllerPopover dismissPopoverAnimated:YES];
pickerControllerPopover = nil;
return;
}
// Deselect any selected cell
[self.tableView deselectRowAtIndexPath:self.tableView.indexPathForSelectedRow animated:NO];
// Working code that shows the overlay (camera on) but the overlay takes the whole screen
SRSScanVINViewController *scanVINViewController = [[SRSScanVINViewController alloc] init];
[pickerController setOverlay:scanVINViewController];
UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:scanVINViewController];
[navController setModalPresentationStyle:UIModalPresentationFormSheet];
[navController setModalTransitionStyle:UIModalTransitionStyleFlipHorizontal];
[[UIApplication sharedApplication] setStatusBarHidden:YES];
if([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPad)
{
pickerControllerPopover = [[UIPopoverController alloc] initWithContentViewController:pickerController];
[pickerControllerPopover setDelegate:self];
[pickerControllerPopover setPopoverContentSize:CGSizeMake(320.0f, 460.0f)];
[pickerControllerPopover presentPopoverFromBarButtonItem:sender permittedArrowDirections:UIPopoverArrowDirectionAny animated:YES];
}
else
{
[self presentViewController:pickerController animated:YES completion:nil];
}
}
I'm totally out of ideas. I can't see why the controls within the overlaycontroller would work fine every time I call it except for the first time.
Thanks for anyones help in advance.
So the answer is that the superclass is mucking with your view. I'm going to guess it was not designed to be subclassed, but no way to know for sure. What it does in one of the 'view..' methods is to override self.view with its own view, and make your view a subview of that view. The first time around it makes the frame of your view have zero dimensions. The next time it leaves it as it was before - maybe some persistent flag. It also inserts the view at different places in its subviews, which seems odd but if you have the code you'd probably see why.
Soooo - the solution to the problem is to just move your view's subviews to the superView (the subclass's view), then set your view's frame to the null frame:
- (void) viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated]; // StackOverflow says to add this TCL?
// Set the initial scan orientation
[self setLayoutOrientation:self.parentPicker.orientation];
if ([self.parentPicker hasFlash])
{
[flashButton setEnabled:YES];
[flashButton setStyle:UIBarButtonItemStyleBordered];
[self.parentPicker turnFlash:NO];
} else
{
[flashButton setEnabled:NO];
}
textCue.text = #"";
viewHasAppeared = NO;
// move the subviews
while([self.view.subviews count]) [self.view.superview addSubview:[self.view.subviews objectAtIndex:0]];
self.view.frame = CGRectMake(0,0,0,0);
}
PS: note that you were missing a superView call here but it didn't seem to matter much (you don't know which method your complex superclass may want so I'd be sure to send them everything you intercept.
I'm attempting to embed an editable UITextView inside a UIPopoverController, with... strange results. The steps I've taken are:
Create a custom UIViewController class, and create a .xib file with that controller with a UITextView inside it.
When the UI action that should bring up the controller occurs (touch up inside), I instantiate the controller and its view from the .xib file.
I create a new UIPopoverController, with the view controller I just instantiated as the content view.
I present it with presentPopoverFromRect:inView:permittedArrowDirections:animated:
Here's some example code:
- (void)noteButtonPressed:(id)sender {
self.noteview = [[MyTextPopupViewController alloc] initWithNibName:#"MyTextPopupViewController" bundle:nil ];
UIPopoverController *popoverController = [[UIPopoverController alloc] initWithContentViewController:self.noteview];
self.popover = popoverController;
self.popover.delegate = self;
[self.popover presentPopoverFromRect:((UIView*)sender).frame
inView:self.view
permittedArrowDirections:UIPopoverArrowDirectionAny
animated:YES];
}
Then, inside MyTextPopupViewController, I make sure the the text view is the first responder to bring up the keyboard:
- (void)viewDidAppear:(BOOL)animated {
[self.view becomeFirstResponder];
[super viewDidAppear:animated];
}
And that all works... right until it doesn't. Sometimes, it works perfectly; other times, either immediately or after a few keystrokes, the application crashes by exiting the main event loop (!). No exception is thrown (at least not that the lldb catches), but the application simply stops, both on the simulator and on hardware.
Any thoughts? Has anyone gotten this working successfully, or knows for sure that it does not?
I think the UIPopoverController instance needs to be a property in your code.