My programe does drag and move a little imageview by touch. When the location is decided, press a button to pass imageview to its superclass.
-(void) sendPosition:(CGPoint)position ;
when I run program for first, it runs ok but after I rerun the same process right after that, it occurs error.
Uhm..
-(void) sendPosition:(CGPoint) position withImageView:(UIImageView*) imageView;
maybe? (Sorry if this sounds stupid but I'm not sure if I understand your question correctly)
Related
I've got a UIPageViewController set up paging my ImageViewController.
The ImageViewController contains a UIScrollView with a UIImageView inside. Nothing else.
I'm testing at the moment with 3 "items" in my datasource for the UIPageViewController (i.e. three pages).
It all works fine and I can scroll and zoom and then page for about 30 seconds and then suddenly I get this warning...
*** Assertion failure in -[_UIQueuingScrollView _didScrollWithAnimation:force:], /SourceCache/UIKit/UIKit-2372/_UIQueuingScrollView.m:778
I've got no idea where to start debugging it though as it doesn't point to any of my code and there isn't any of my code in the stack or anything.
Can someone give me a pointer as to where to start debugging this.
EDIT
I've done a bit more testing. It seems to happen if the scrollView is decelerating (i.e. after a flick) and then I try to transition the PageViewController to another ViewController as the scrollview is still moving.
The app crashes about 20% of the way through the transition to the next page.
EDIT 2
The error seems to stop on the line _cache_getImp (not sure if that's a capital i or lowercase L).
EDIT 3
This gets better. I just downloaded Apple's PhotoScroller sample app to see if they got round the problem a different way. Well, no, they didn't. The sample app crashes in exactly the same way mine does! You have to zoom and scroll and transition pages at the same time to make it more likely to crash but it happens on it's own too it just might take longer to happen.
Came up with a solution! In my case I have a UIPageViewController with UIPageViewControllerTransitionStyleScroll as well as next buttons that allow the user to advance through my viewpager by tapping. I am getting this crash when the user presses a next button and drags around slightly before releasing their finger (still within the frame of the button). It appears that the dragging within the button is interfering with UIPageViewController's pan gesture recognizer in this case, and that's what causes the crash.
While it's pretty unlikely that the user will get in this state, I've come up with a relatively simple solution the prevents my app from crashing if it does happen. I have a boolean that represents if the user is in a valid state to move to the next screen and set it to YES on touch down, then to NO if the user drags anywhere inside my button. Then, on touchUp (nextPressed) I check the boolean before moving my UIPageViewController programatically.
- (IBAction)touchDown:(id)sender
{
self.shouldAdvanceToNextScreen = YES;
}
- (IBAction)touchDragInside:(id)sender
{
self.shouldAdvanceToNextScreen = NO;
}
- (IBAction)nextPressed:(id)sender
{
if (self.shouldAdvanceToNextScreen) {
UIViewController *initialViewController = [self.storyboard instantiateViewControllerWithIdentifier:#"TutorialScreen2"];
NSArray *viewControllers = [NSArray arrayWithObject:initialViewController];
[self.pageViewController setViewControllers:viewControllers direction:UIPageViewControllerNavigationDirectionForward animated:YES completion:nil];
}
}
The downside is that nothing will happen even though the user still released their finger within the button frame. However, I prefer this over a crash and see this as a pretty rare edge case regardless. I'd expect the user would just tap again - this time without a tap & drag - and move forward successfully.
I'd welcome any ideas on taking this a step further and preventing the clash between the touch drag and the UIPageViewController altogether.
Have you tried disabling bouncing in the UIScrollView? That worked for me and solved my other problem too alluded to in my comment above.
I have been fighting with this all day.
My Conclusions:
If you have a scrollview as the showing ViewController and you are delegate of the scrolls: you're in trouble. Even with the PageViewController configured with Horizontal scrolling, a vertical scrolling on your view will trigger an event. -> this does not cause trouble if: you scroll back to the top of your view before (Not sure how to fix this).
There are good StackOverflow threads like this one.
Basically the solution is:
1 [yourView setViewControllers:yourControllers direction:UIPageViewControllerNavigationDirectionForward animated:NO completion:nil];
2 Use UIPageViewControllerTransitionStylePageCurl as the transition Style.
This fixed most of my problems.
If someone has a solution for the delegation problems with the scrolling, will be most wellcome
I had a similar problem. My setup was a UIPageViewController and I was loading view controllers with an UIImageView inside. When interacting while the UIPageViewController was scrolling I got the same crash log.
I fixed it by creating a UILongPressGestureRecognizer and add to the UIPageViewController's scroll view.
Created my own subclass of UIPageViewController (Solution is specific for my case but can easily used as a generic solution)
Find the inner UIScrollView of the UIPageViewController
- (UIScrollView *)findScrollView
{
UIScrollView *scrollView;
for (id subview in self.view.subviews)
{
if ([subview isKindOfClass:UIScrollView.class])
{
scrollView = subview;
break;
}
}
return scrollView;
}
Add the long tap gesture recognizer to the inner scroll view and point its action to a method or nil
/**
* On tap-hold the page view controller crashes as soon as it pages to a new view controller.
* Setting a long press gesture to ignore the hold.
*/
- (void)listenForLongPressGestureOnScrollView:(UIScrollView *)scrollView
{
UILongPressGestureRecognizer *longPressGestureRecognizer = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:nil];
[longPressGestureRecognizer setMinimumPressDuration:0.5];
[scrollView addGestureRecognizer:longPressGestureRecognizer];
}
It surely looks like a bug in iOS 8 and 9.
(and the "answers" down below attempt to work around that)
Feel free to file a ticket on bugreport.apple.com
Do be sure to specify how to crash PhotoScroller
Include all iOS versions you've seen it crash on
To date I've seen:
Assertion failure in -[XXX.TrackingPageViewController queuingScrollView:didEndManualScroll:toRevealView:direction:animated:didFinish:didComplete:], /BuildRoot/Library/Caches/com.apple.xbs/Sources/UIKit/UIKit-3512.60.12/UIPageViewController.m:2028
Assertion failure in -[_UIQueuingScrollView _didScrollWithAnimation:force:], /BuildRoot/Library/Caches/com.apple.xbs/Sources/UIKit/UIKit-3512.60.12/_UIQueuingScrollView.m:785
(lldb)
I'll keep the list updated (Despite the downvoting, however massive).
Stay tuned.
It does not look like our bug.
UPD 2016 09 27 (on Xcode 8 now):
Assertion failure in -[XXX.TrackingPageViewController queuingScrollView:didEndManualScroll:toRevealView:direction:animated:didFinish:didComplete:], /SourceCache/UIKit/UIKit-3347.44.2.2/UIPageViewController.m:1875
awesome
In my app I have a UIImageView and at runtime once I download the image I am changing the image through postnotification but the image was not getting changed and I checked all my connections in nib and everywhere and it looks fine for me but still the image was not getting displayed can anyone help me in this regard. And my uiimageview was inside a scrollview and the scrollview was inside my main view
the following method was called on postnotification
- (void) refreshimages:(NSNotification *)notofication {
if ([[notofication name] isEqualToString:#"DownloadImgBinary"]) {
[activityview stopAnimating];
[activityview removeFromSuperview];
[self.view bringSubviewToFront:scrollView];
[self.scrollView bringSubviewToFront:imgCamera];
self.imgCamera.image = td.imgPhoto;
}
}
You need to check two things.
First, make sure that you are actually receiving the notification.
Put a breakpoint in the observer's target method, or stick an NSLog in there. If, when you do this, you see neither of them, then your notification isn't getting received.
Second, make sure that the image is actually getting downloaded.
Either use a web debugging proxy (I use Charles but it costs a bit, there are alternatives), or again, breakpoint somewhere. Or stick in a manual button somewhere that on-press tries to set the UIImageView's image, run the app, and press the button after you're sure the image downloaded.
Finally, to make sure something fishy isn't going on, stick two images in your project, give the imageView a default image (something glaringly obvious like checkerboard pattern), and then in the notification (assuming it is firing), set it to something else that is also glaringly obvious. Then test. This way you know that the bring-subview-to-front is working, and that your IB links are working.
probably a very simple question but can't find the right answer anywhere. I am using XCode 4 and working on an iphone app, which probably sums up all the info that I need to provide.
Here it is:
- I created a ViewBasedApplication
- At some point depending on the user input, I load a TableView
But now how on Earth do I add a button or something to return? Note: I can't use a NavigationBased app, that would be easier but would not work for me.
Help anyone?
If you used a UITableViewController, you may want to use a UIViewController instead. In the UIVeiwController, you can add a UITableView along with your own UINavigationBar or, if you don't want to use a UINavigationBar, you could leave room for some type of custom UIButton. Either the UINavigationBar button or your custom UIButton action could trigger a close of your UIViewController.
If you add the UIViewController as a subview, then Cyprian's [self removeFromSuperView]; would work. If you present as a modal as Jamie suggests, you could use [self dismissModalViewControllerAnimated:YES];.
Well I don't know you code but you could always call
[self removeFromSuperView];
So in my app delegate I add a call add the myViewController.view to the main window:
1. [window addSubview:myViewController.view];
In myViewController I do the following code in the viewDidAppear method:
2. [self presentModalViewController: yourViewController animated: YES];
In my yourViewController class I do the following to try and go back to the main window
3. [self dismissModalViewControllerAnimated:YES];
My main windows view appears with buttons in all, but the buttons won't react to any click or anything. It's like there is something over them that I can't see.
Also, the main windows button works before this process but doesn't after the process.
Any help would be appreciated.
If the dismiss method call is in the modal view controller (not the parent that presents it), then you actually want to call [self.parentController dismissModalViewControllerAnimated:YES];
There are a number of reasons why things might not be responding to your touches. Here are two that have happened to me:
The frame of the view you want to touch is too small. UIViews can draw outside of their frames, so it might look ok, but not respond if the touch is technically outside of the frame -- you also have to check that all the superview's up the hierarchy also have a large enough frame.
If anything in your view is a UIImageView or child thereof, it won't respond to user touches because UIImageView has userInteractionEnabled set to NO by default. You can fix this just by setting myImageView.userInteractionEnabled = YES;
Edit: Oli pointed out in the comments that dismissModalViewControllerAnimated: should work if called on either self.parentController or simply self, since that method is smart enough to call the parent if needed, according to the docs. The docs also make it sound like this might behave differently if you have multiple model views open at once, though, so I would still consider it cleaner code to call the method on self.parentController directly.
I am trying to add an info button to my app to provide custom help.
Instead of adding the button to the nib and linking the event (touchUpInside) to the controller, I decided to add the button programmatically. The button shows up. When I add the target event handler to be executed when the button is touched, it does not work. That my method(doHelp) is not being called on touching the button.
When I debugged it, the event is not registered with the button! Although the code does not throw any exceptions.
Here is the code snippet FROM the view:
// Create a Button to get Help
UIButton *helpButton = [UIButton buttonWithType:UIButtonTypeInfoDark ] ;
buttonRect = helpButton.frame;
// CALCulate the bottom right corner
buttonRect.origin.x = rect.size.width - buttonRect.size.width - 8;
buttonRect.origin.y = rect.size.height - buttonRect.size.height - 8;
[helpButton setFrame:buttonRect];
[helpButton addTarget:self action:#selector(doHelp:) forControlEvents:UIControlEventTouchUpInside];
[helpButton setEnabled:TRUE];
[self addSubview:helpButton];
........
// Another METHOD ELSEWHERE in the VIEW object
-(void)doHelp:(id)Sender
{
[self setHelpNeeded:TRUE];
[self setNeedsDisplay];
}
What am I doing wrong please?
I have looked at the SDK help and samples and am really flummoxed!
Am hoping another pair of eyes will help! :-)
This code snippet is in the View Object in case you need to know.
I just added the doHelp to help the first 2 responders... thanks.
**UPDATE 6/4/09 ** -
I have been trying all night and nothing worked. I think there is something wrong in the way I have set up the method selector as my method never gets called. Everything else looks fine. Even using a NIB file does not work. I have tagged the button, retrieved it and added the method selector but to no avail. There is something fundamental which I am doing wrong... Argh!!!
Any ideas, anyone?
Resolved it finally!!! and learnt something in return. Did cost me a few days to figure this out.
The reason my UIButton object was not working was because I found that in case of a UIIMageView object:
"initWithImage: This method adjusts the frame of the receiver to match the size of the specified image. It also disables user interactions for the image view by default."
AND my UIButton had been assigned as a subview of a UIImageView control !!!
There was no errors / warnings. It just gets disabled quietly.
Solution: Created a container UIView object which now contains the UIImageView AND the button so that the button appears as overlayed on the Image but it is actually a sibling of the image and a subview of the dummy container UIView.
It's been awhile, but I think your addTarget needs to take the object that contains the doHelp: selector, like so:
[helpButton addTarget:self action:#selector(doHelp:)];
assuming somewhere in that same View you have:
- (void)doHelp: { }
passing nil to addTarget means that you're sending that selector to no recipient.
The problem is your addTarget:nil there. The selector you gave it for action is just a message it'll send to its target. You didn't give it a target, so it doesn't know what to do with that message. You probably want to pass in self instead of nil there.
I came across this while googling for a solution to the same problem. At least with the 3.x SDK, all you have to do is set the UserInteractionEnabled property of the UIImageView to YES.
Thanks for posting your discovery about the problem, I wouldn't have even thought to look at that one.
I had a similar problem where Buttons were outside of the view and did not receive tap messages
what helps is to set background colour of the parent view, to see that button is outside of it:
...
[buttonParentView addSubview: myButton];
buttonParentView.backgroundColor = [UIColor cyanColor];