i am having some very strange issue. Basically i am implementing a drag and drop view with a snap to the horizontal 1D grid. Well, so when i drag a view and its center coordinate X is bigger or smaller then a different view, the non-dragged view should be animated to the left or right of its original position.
This works fine most of the time. But in some special cases its not working. In some situations specific situations the view does not receive any gesture callbacks anymore. I can reproduce this issue and have found out that when i remove the code that applies the animation, everything its working fine.
Basically this is the code that is called when the dragged view is at a position where the view below should be moved to the left or right
/**
* Animate element to its saved position
*/
- (void)switchElement:(unsigned int)draggedIndex with:(unsigned int)otherIndex
{
// first animate
UIView *view = views[draggedIndex];
UIView *otherView = views[otherIndex];
// IF I COMMENT THIS OUT, EVERYTHING WORKS FINE
otherView.frame = [self getImageRectForIndex:draggedIndex];
// now switch internally
if(draggedIndex != otherIndex)
{
// switch views
views[draggedIndex] = otherView;
views[otherIndex] = view;
}
}
Any idea if there is something to have in mind if i animate UIViews and have gesture recognizers attached to them?
If somebody is willing, i can paste the whole class here to test it.
SOLUTION
I am having some "highlight" views in my design. And i have moved the relevant views behind those transparent background views by accident. So now i am not using addSubview: but insertSubview:atIndex: instead.
But marking #Anthonin C. answers as the right one. Because it pointed me in the correct direction (I found it out by overriding the hitTest: method)
Would you please track the otherView.bounds property to verify that your touch isn't out of bounds. I faced this issue recently and Apple documentation provide solution here : Delivering touch events to a view outside the bounds of its parent view
Sorry, I don't have enough reputation to comment your answer.
Related
Context
I am using this simple library to make an intro/walkthrough for my app (TL;DR, horizontal paging view controllers). I currently have 3 pages setup.
In the 3rd walkthrough page, I have a custom CALayer that animates a circle in an endless loop. I'd like to add that layer to a UIView in order to lay it out the way I want in IB (via auto layout).
In viewDidLoad (for the 3rd page) I create the circle layer and set its frame to be the same as the view I positioned, assuming the circle would be in the same spot as the view:
for v:UIView in [view1!, view2!] {
var pulse = PulseLayer()
pulse.frame = v.frame
pulse.cornerRadius = v.frame.width / 2.0
pulse.masksToBounds = false
view.layer.insertSublayer(pulse, above: v.layer)
}
Problem
When I run the app in the iPhone 6 simulator, the CALayers show up OUTSIDE their UIViews (see below).
One thing I noticed immediately is the layers are not misplaced the same way--one is above its view, and the other is to the left. I am assuming this is related to the constraints on the views, but I cannot figure out how to fix it.
Equally baffling to me is that when run on the iPhone 5 simulator, the layers appear exactly as I expect them to (see below).
I feel like I am misunderstanding some of the concepts at work here. How can I get the positioning to act the same? (Like the iPhone5 gif.)
Or, is there a better way to do what I am trying to do?
viewDidLoad is too soon. Remember, viewDidLoad is way early; the view is not in the interface yet and nothing has its ultimate size/position. If you're going to add the layers to view rather than as sublayers of the little views, you will have to run your layer-creation code much later, in order to get the position right. viewDidAppear: or viewDidLayoutSubviews will be safe - but of course you must use a bool flag so you don't do it too many times.
Personally I don't see why you don't add the layers to the little views. So you would just set pulse.frame = v.bounds and add as a sublayer to v, not to your view. It solves the positioning and gets the relationships right. And doing it in viewDidLoad would work, because when the views move, the layers move with them.
I'm having an issue with my app's layout which is a bit tricky to explain. When the app first starts, this is what I'm showing:
After the user taps "Create Profile", I animate those buttons and show a registration form instead:
Needless to say, the buttons are now not in their "natural" position. Note, however, that the text fields are - that's where I have placed them in the storyboard, but when the view first loads I hide them. The animations are working great, but then I needed to scroll my view up when the user gives focus to a text field and the keyboard hides the field. The details of how to trigger the bug are a bit hard to explain, so I managed to boil it down to what seems to be a redraw event, except that it isn't... Let me try and explain that.
First of all, here's what happens when the keyboard is about to show:
- (void)keyboardWillShow:(NSNotification*)notification
{
CGRect frame = self.view.frame;
frame.size.height -= 1;
self.view.frame = frame;
}
Notice that this is a test only, probably the minimal I found that would still trigger the bug. All it does is resize the view. I would expect the view to be exactly as it was, with one less pixel, right? Wrong. Here's what I get:
That is, all elements returned to their "natural" positions, completely ignoring their previous positions. My first guess was that it would seem that the window is redrawing, so I tried this:
- (void)drawRect:(CGRect)rect
{
[super drawRect:rect];
NSLog(#"View was drawn");
}
But this only triggers when the window is first drawn, not when this strange behaviour happens. To understand what I mean by "natural position", here's what I have in storyboard:
You can also see that I'm not using constraints and the underlying structure of my view:
The full code for the entire setup is quite extensive, so pretty much not practical at all to show. However, how I animate the subviews resumes to changing their frame as I did in keyboardWillShow, and setting their positions to whatever I need.
Any ideas?
So you're using storyboards and you have "Use AutoLayout" set to false for your entire storyboard?
In that case your app is using "struts and springs" style placement rules. You're going to have to debug those.
It's a bit hard to describe everything in a view controller in a post. It's easier to go over it in IB. Perhaps you can write a utility function that logs all the autoresizingMask values for the views in your view controller, and go over those, and perhaps post them here describing the autoresizingMask values for each view in your original post.
I'm trying to take a snapshot of a hidden view but am running into several issues. If I try unhiding it quickly, taking a snapshot, and then rehiding it, I sometimes get a quick flicker on the screen that is pretty jarring.
toCollectionViewCell.hidden = NO;
UIView *toPlaceHolderSnapshot = [toCollectionViewCell resizableSnapshotViewFromRect:toCollectionViewCell.bounds afterScreenUpdates:YES withCapInsets:UIEdgeInsetsZero];
toCollectionViewCell.hidden = YES;
I'm pretty sure the flicker is caused by the afterScreenUpdates:YES, but I can't imagine that is intended behavior.
I've also tried moving the cell/view off screen instead of hiding it, but I can't be certain when that cell might be reloaded and therefore moved back into its place prematurely.
Is there a way to take a snapshot of a hidden view or a more clever way to achieve this? I need this functionality during a custom transition animation where I am pulling a collection view cell out of the collection view and then returning it back into place on dismiss. I am taking snapshots of the before/after state and then transitioning between the two during the animation.
Thanks!
Add an extra container view to your view hierarchy. Hiding the container will have the same visual effect, but you'll be able to snapshot the content of a container with ease.
I've also tried moving the cell/view off screen instead of hiding it, but I can't be certain when that cell might be reloaded and therefore moved back into its place prematurely.
This approach is probably the simplest. As long as all of your work is done on the main thread, the cell won't move during your snapshot.
You could also try archiving and then unarchiving the view (to essentially copy it):
id copyOfView =
[NSKeyedUnarchiver unarchiveObjectWithData:[NSKeyedArchiver archivedDataWithRootObject:originalView]];
UIView *viewCopy = (UIView *)copyOfView;
viewCopy.hidden = NO;
(All views in the hierarchy will need to conform to the NSCoding protocol.)
Finally, you could draw your cell to a UIImage, and then display it in a UIImageView. Sample code here.
I know this has been probably asked before but I've seen many approaches and i don't know which is best for me, so plz don't send me a link to another post unless it addresses my problem directly.
I have a controller which has a uiview on the top (like a header) (this header is bigger than it seems because is partially hidden on top). on that view i have a uibutton which now with a touch up inside shows the entire header view and taping again returns it to its starting position (changing frame with animation). I want to also be able to drag the view but only changing position on the y axis(dragging up and down)... i was thinking of adding the dragInside/Outside event to the button but this doesn't give me the position of the finger... and also want to know when the user releases the drag so the view ends animation to any of its two possible states (showing or partially hidden). Is this a "touches began" , "touches moved" , "touches ended" thing? if it is please provide a code example. I also want to do this with another view but this is on the left side... same thing but this one moves on the X axis... any help is appreciated. or maybe it can be made with drag event if i only can save a CGpoint of last touch, maybe that's better, any other suggestions
Look at using a UIPanGestureRecognizer to detect the touch movements. Use the translationInView: of the gesture to set the view y position. The translation is the total movement since the start of the gesture so you don't need to remember and accumulate the offset position yourself.
The main thing to worry about while implementing this is bounding the y position of the view so that no matter how far the user drags the view won't go too high or low on the screen.
Use a UIPanGestureRecognizer, that's a class dedicated to handling such drag/pan gestures.
Everything is described here in Apple's documentation, including examples, so you should find your answer here.
There is also some sample code in Apple Developer Library that shows you how to use Gesture Recognizers if needed.
It was necessary to create a subclass of UIButton, lets call it subButton. These subButtons are instantiated one by one and dynamically added to an UIScrollView object.
Unfortunately the subButtons aren't reacting as expected. After scrolling away from the first dynamic generated subButtons and then returning back to them. They loose their reactivity to single tapping. I can not explain this behaviour. Can somebody explain why its behaving this way?
Many thanks.
Source code
self.subButton = [[SubButton alloc]initWithFrame:CGRectMake(69.5, y, 201, 114)];
[self.subButton setBackgroundColor:[UIColor blueColor]];
self.subButton.imageData = imageData;
self.subButton.videoPath = videoPath;
self.subButton.vidIndex = _indexVideo +1;
[self.subButton drawVidPreview];
[self.subButton setTag:(_indexVideo +1)];
[self.subButton addTarget:self action:#selector(handleSingleTap:) forControlEvents:UIControlEventTouchUpInside];
[self.videoScroll addSubview:self.subButton];
[_videoPreviews addObject:self.subButton];
The subButton method drawVidPreview adds some subviews to itself.
Do the buttons not respond at all, or just not to single-tap? That might help us help you.
If they don't respond at all, I would check your view hierarchy to make sure no other view (perhaps invisible) are sitting above your buttons. Or, perhaps are the buttons not being added to the parent view you think?
Please make sure you are not adding the same UIGestureRecognizer instance to all of the UIButtons, instead for each UIButton you need to add a separate instance, however all gesture instance can point to the same target.
At last, i could solve the problem. The reason why the first subButtons did not respond to single tapping with UIControlEventTouchDown is because the uiScrollview content offset was set to a negative y value. This first of all was not necessary and was done out of pure laziness. I corrected it by giving it a positive value.
So my conclusion is, if you do not set the content offset or content size of the scrollView correctly, some dynamically added buttons to the scrollView might not respond to tapping appropriately. This is even the case if all Buttons are placed completely on a uiScrollview object.
This I could confirm by playing around with the content size of the uiScrollview instance too. I changed size of the y value of uiScrollviews instance just by few points and then some of the last buttons did not respond to tapping anymore.
Just by increasing the content size of the y value again, made the buttons responsive again.