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.
Related
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.
In storyboard, I have buttons attached to main view as siblings to SCNView(both buttons and SCNView are subviews of main view). At launch time, the buttons appear on screen before the SCNView does. This is quite unfortunate. Do you have any idea how to fix this?
//edit: added button programatically in viedDidLoad: as a subview of SCNView..Still the same problem.
SettingsButton and View appear before SceneView. This happens on iPhone 5,5c and lower and on iPads.(3 for sure, don't know for others)
Code for adding view programatically:
let uv = UIView(frame:myFrame)
uv.backgroundColor = UIColor.blackColor
sceneView.addSubview(uv)// scene view from storyboard
Thats it. How can iOS take 5-10s to load an app, but than rushes with adding views to the screen in an unpredictable order.. Couldn't it just take 0.2s more and present view properly? Really stupid problem
I imagine if you check via debugger breakpoints or logging in viewDidLoad, you'll find that the SCNView instance is indeed in the view hierarchy immediately.
What you're seeing is that said view's SceneKit content does not appear immediately. Depending on what you're doing with SceneKit, it may take some time to load content and prepare for rendering, and during that time the rest of the view hierarchy remains visible. That delay is probably unavoidable — you might be able to minimize it by optimizing asset formats, reducing the amount of stuff in your scene, etc. So it sounds like the key issue here is getting your app launch experience to look the way you want while accounting for the delay.
A good way to do that might be to show a splash image of some sort until SceneKit is ready to display. You could put a UIImageView in your storyboard, set up to obscure everything with a splash screen (possibly the same launch image iOS displays before your app takes over), then hide that image view (with a fade out even?) when SceneKit starts rendering.
To find out when SceneKit starts rendering, make one of your objects the scene renderer delegate and implement renderer:didRenderScene:atTime:. That method gets called on every frame, so you can use it to catch when the first frame has been rendered (and then ignore it for subsequent frames).
So here's the situation:
I have let's say 20 views who are all subviews of the same view. Now I want to remove and add new views in an animated matter.
I previously did this by using regular UIView animations and fading them out or in respectively. The problem is though that the animation isn't flawless when the new subview who is to be inserted overlaps with the subviews who are fading out. So I tried using the +[UIView transitionFromView:toView:...] animation block to make the animation cross dissolve. This works well, animation looks good.
This basically solves my issue. The only problem is that it might be that I want to replace 2 subviews with one bigger subview. This doesn't really work out as I can't just pas nil to the transition method.
So my question basically is how I can simultaneously cross dissolve multiple subviews no matter how many views are animated?
Thanks for your help!
Have you tried putting the views to remove inside a transparent bigger view? So you just call transitionFromViewToView using the container with the 2 little ones inside and the big one that is entering?
You can use + [UIView transitionWithView:duration:options:animations:completion:], passing the common superview (usually self.view of your view controller) to perform all animations at once.
Excerpt from the doc:
This method applies a transition to the specified view so that you can
make state changes to it. The block you specify in the animations
parameter contains whatever state changes you want to make. You can
use this block to add, remove, show, or hide subviews of the specified
view. If you want to incorporate other animatable changes, you must
include the UIViewAnimationOptionAllowAnimatedContent key in the
options parameter.
I am developing a little MS tweak that adds a view on the Springboard. I want it to be constantly updated so I called it into the
- (void)showSpringBoardStatusBar
Then I create and add the view using this:
[[UIApplication sharedApplication].keyWindow addSubview:view1];
Is this the right way?
But the problem is this view uses a low alpha level to be transparent and every time the view is updated by the showSpringBoardstatus bar another UIView is added onto of it eventually just making the view solid. This also is uneconomical in terms of memory. so then I went back an added what I thought would remove the code:
view1 = nil;
[view1 removeFromSuperview];
But it seems like this doesn't make a difference as it is still there and nothing changes.
I have been searching for the last few days for anything to help me with this but got nothing out of it. All I can think of is that I can't remove an added subview from a key window like I would from a normal view or I just don't how to do it correctly.
Any help would be appreciated. Thank you.
Setting view1 to nil and than calling "removeFromSuperView" might be a bad idea. How about adding the view only once, keeping a reference and updating this reference constantly without adding it to keyWindow again?
My app needs to save an image to disk. I do this in a separate thread, so the UI is still responsive, BUT, I do not want the user to add a new image until the first one is saved (about 1 second.)
At the moment, I'm disabling the 'take another picture' button and greying it out, but I'm wondering if there is a method that will disable the whole view, greying out the buttons and darkening the background, like what happens when a UIActionSheet is presented.
I've looked through the UIView docs and don't see anything like this, but it seems like such a useful pattern that is frequently used by Apple that I figured I'd ask, just in case there was such a thing.
Obviously I could do it manually, but why reinvent the wheel if its already part of the API.
TIA: John
set whatever view (main view, subview, etc.) you want to appear disabled to
view.userInteractionEnabled = NO
and also
view.alpha = 0.3f
and maybe even
view.backgroundColor = [UIColor grayColor]
to boot. These last two can be animated, b.t.w.
Present another view with the shadow and the gradient etcetera over this view thus giving it an effect of graying out with shadows. You may even create an image if you know your photoshop. Just show that image on a UIImageView over this view to be blocked. Give the image some nice translucency, shadows etc etc