In the Facebook app, when you're on the feed, and you tap on a photo to view it, a few things happen:
The image animates/moves to the center of the screen, no matter where its current position in the table view (middle, partially off the screen towards the bottom, top, whatever)
As the image moves to the center of the screen, the rest of the table view is faded out (alpha = 0)
When you drag the image up or down, the alpha of the table view is restored proportionally (I think) to the offset of the image from the center of the screen
At this point you'll notice that in the Feed, the place where the image used to be, is now empty (giving you the impression that you 'brought' that image up front). You see this by dragging the image up/down and you can see the Feed/table view behind the image.
Following #2, if the image is already proportional (that is, the image's preview on the Feed/table view was a proportionally-scaled one without any cropping) then it just moves to the center. If the image was cropped at all (because it was too tall, etc to fit properly in the Feed) then the rest of the image is revealed at the same time that it is moved to the center of the screen.
Once the image moves to the center of the screen, the gallery view controller elements show up (Done button, Like/Comment buttons, etc)
Following #4, if you swipe to another image (swipe left/right in the full-screen image view to another image in the same album), and then attempt the drag up/down in #3, you'll see that the first image is back to where it was in the Feed.
Finally, if you drag the image up/down past a certain threshold, it is dismissed and the Feed is revealed again.
This is what I think is happening conceptually, and I'd like some confirmation if this is the right approach (these bullets below don't map to the bullets above):
When user taps on an image, add that imageView as a subview of the table view's container view, but add it at the exact same position so that the movement of the imageView from the cell into the main view is not seen.
Then animate the movement of that image to the center of the screen. At the same time, reduce the alpha of the table view so that it reaches 0 at the same time that the imageView reaches the center of the screen.
Once the image reaches the center of the screen, push a modal view controller without animating it, and add the imageView as a subview of the modal view controller's view (effect #6 above)
Any dragging of the image reduces the alpha of the modal view controller and increases the alpha of the Feed table view (effect #3 above) and dragging above a certain threshold triggers the animation that hides the gallery and shows the Feed again (effect #8 above)
Questions:
Am I on the right track? If so, how do I bring the imageView from the cell into the front view - and keep it at that very same position?
When you swipe to another image, the original image is 'restored' into its original location in the cell of the table view. Is this actually just moving one imageView from one view to the next? How the heck do you send it back to the original cell - keep a pointer to that cell when the user taps on the image, and then do something like customCell.imageViewContainerView addSubview:originalImageView? This then needs to be reversed if the user swipes back to the original image?
This whole thing to me seems like a non-trivial implementation, but I think the effect is awesome and I'm also damn curious as to how it's done. Am I overthinking it and there's actually a really easy way to do it, or am I right to give props to whoever wrote the FB app?
Am I on the right track? If so, how do I bring the imageView from the cell into the front view - and keep it at that very same position?
I think that you are right on the conceptual steps. It's not difficult to get the imageView from the cell and add it to the controllers view. You can use the methods like
- (CGRect)convertRect:(CGRect)rect toView:(UIView *)view
to get the correct position for the imageview.
When you swipe to another image, the original image is 'restored' into its original location in the cell of the table view. Is this actually just moving one imageView from one view to the next? How the heck do you send it back to the original cell - keep a pointer to that cell when the user taps on the image, and then do something like customCell.imageViewContainerView addSubview:originalImageView? This then needs to be reversed if the user swipes back to the original image?
I think that this is made by some kind of protocol between the gallery and the table view controllers. Maybe it just hide/show the image, and the images in the gallery are actually a different object.
Anyway, if you want to use the same imageview, you can send the object with the protocol between the two controllers.
Hope this helps a little ;) I think that key is in the convertRect methods.
Related
I have an UIImageView which covers all of my screen. The pictures that I'm displaying are bigger than it and the .contentmode is set to the.scaleAspectFill So the UImageView is just showing a cropped version of each picture.
In front of them is a CollectionViewController which consists
of multiple pages.
I've used scrollViewWillEndDragging to change my background picture when I move through the pages with a short animation ( each page has a specific background).
Please Help on:
How can I make the background picture move with my touch move horizontally until the scrollViewWillEndDragging happens and move back to its original position if the scrollViewWillEndDragging didn't happen.
Thank you for your time.
Using Swift 4 in XCode, I have several image views on the screen. I have added a gesture recognizer to one, and am able to move that image around the screen with a pan action.
What I'd like is that when I move that image NEXT to another image view on the screen, it "snaps" into place right next to it. (imagine magnetic lego blocks - and when one gets close to the next one, it snaps and attaches) -- as opposed to, say, being able to drag the movable image on TOP of the static image.
Can anyone guide me toward an answer, as I don't know what this concept is called.
(I'm not really trying to use animation, as it should only move based on a user's swipe.) Any tutorial links would be appreciated! Thanks!
I want to create a page with a big image as background and buttons that users can interact with.
So imagine I put a big image such as a piece of map into the screen, but I only show a corner of the map in the display. So if a user wants to see other parts of the map, they have to "scroll" and navigate to wherever they want.
Meanwhile I also want to put a button they can tap on, and that button should lead to a php webpage (in-app, not opening in safari or else) or information page about sites and buildings in this location.
I am a rookie and I haven't have any code written down yet. I am thinking about using UIScrollView and UIButton, but am I on the right direction? Any advice?
Thanks in advance!
First you need a way to pinch zoom the image. In this mode, you can drag the image in any direction that you want. A common method can be found here. A scroll view can only scroll horizontally or vertically but with that image zooming, each image can be zoomed in and then dragged to any direction you want. You can have a scroll view with only one image.
After you have the image zooming ready, all you need to do is to create a subview on your screen to cover part of the image view or scroll view, whatever you used.
I have a UITableView and I would like that when they enter a certain area of the device, the cells' content view would appear to be reduced.
Only the part of the cell in this area would be scaled down. How can I achieve that?
I guess it has to use a UIView as an overlay view and apply a transform somehow to the underlying view that crosses it but I have no idea how to do it.
You can take a snapshot of the cell in question (before you leave the table view) by calling snapshotViewAfterScreenUpdates: with argument false on the cell. Now, as you say, you do whatever you want with the resulting snapshot view, including transforming it to be smaller.
Moreover, you can place the snapshot view into the interface and animate the change in its transform as part of the transition to the next view controller. That's what Apple is doing, for instance, in the Calendar app, when a year zooms into a month.
I want to create a view in which I like to have animation such as the one present in iOS 8 Weather app.
I try to explain more what I have done. If anything is incorrect please guide me.
In the top I put a label for the temperature. (The big one)
Below that label, I put another label to show some text. In the Weather app, there is the horizontal scrollview showing the hourly forecast.
Next is the Table view.
What I want to achieve is that when I start scrolling, the first label disappear smoothly and the second one go to top of the screen and the TableView stretches to show more content.
When I scroll back to the top, I want the whole process to revert.
What is the best way to do this?
I've recently re-created the iOS8 Weather app's scrolling effect for an app I'm creating.
The complete code is too long to post here but for anyone who's interested, I've put it on GitHub. You can download and run the project to see how it looks. Improvements to the code are welcome:
UIScrollView with masked content.
It works like this:
You have one scrollview (the size of the screen), which contains a subview (the mask) which in turn has a subview (the content). We also add a large label to the top of the screen (in the Weather app, this displays the temperature).
Then you use the scrollViewDidScroll delegate method to keep the mask fixed to the screen as the user scrolls. You also use this method to stretch the mask upwards at first.
Fixing the mask to the screen means that the mask's subviews (our content) also becomes fixed. But we want it to scroll, so we do the opposite to the content of what we did to the mask (again, using scrollViewDidScroll).
We need the mask to actually behave as a mask, so we set clipsToBounds = YES on the mask.
Finally, we use the scrollview's offset during scroll to move and fade the big label at the top of the screen.
To make it behave exactly like the iOS8 Weather app, we need to also do the following:
Cancel any scroll touches that happen above the mask, i.e. over the large temperature display.
Ensure that the initial scroll that moves the temperature display is completed programatically if the user doesn't complete it.
Add a sideways-scrolling subview which is anchored to the top of the mask.
I haven't done these yet, though.