I have a collectionView which I need to animate height changes for, so it expands up from the foot of the screen, & back down again. It's hard to explain what's going wrong so I've attached a recording of the simulator. The animation is fine for expanding, but very odd for the collapse - the content partially disappears as it animates, then reappears when it's done. The animation code is triggered during the scrollView 'scrollViewDidScroll(_ scrollView: UIScrollView)' delegate method, with logic to determine whether to collapse or expand. The expand animation, whose code is pretty much identical, works fine.
Animation code -
private func collapseTable() {
guard self.isTableChangingSize == false else { return } // as the delegate method is triggered during the animation, we use a flag to prevent multiple collapse calls
guard self.tableHeightConstraint.constant != self.tableCollapsedHeight else { return } // don't collapse if we're already collapsed
self.isTableChangingSize = true
self.tableHeightConstraint.constant = self.tableCollapsedHeight
UIView.animate(withDuration: 0.5, animations: {
self.view.layoutIfNeeded()
}) { _ in
self.isTableChangingSize = false
}
}
Here are a couple of videos of what's happening -
Normal speed
Slow motion
After far too long messing about trying different approaches, & tweaking everything, it seems that the problem was allowing scrolling during the animation block. If you set -
self.collectionView.isScrollEnabled = false
before the animation block, and -
self.collectionView.isScrollEnabled = true
in the completion, all is good.
Related
I have an app with a build target of IOS 14 that is causing a problem regarding automatic positioning of the view on keyboard show.
I have a UITextView that is draggable and can be positioned partially outside of the main view that it sits within. If the field is large enough then it will extend beyond the parent view and safe area also. The parent view has clipsToBounds set as true so the overflow of the text view is not visible.
The problem is when the text field is positioned so that its right hand side is outside of the safe area and the keyboard is presented, the screen automatically scrolls left to include the far right edge of the text view, even though it is not visible due to clipsToBounds being set on its parent. I need to disable the behaviour that is causing this to happen but can't find anything that covers this for UIKit.
See below for a visual example. Can anybody please help?
Image 1
Image 2
Edit:
The structure of the screen is:
View Controller:
.....UICollectionView:
..........UICollectionViewCell:
...............UIView:
....................Elements (UITextView in this case)
func calculateCarouselOffset(formHeight: CGFloat) -> CGAffineTransform {
let carouselOffset: CGAffineTransform!
let currentElementMaxY = returnCurrentElementMaxY()
let elementMaxYTransformRemoved = currentElementMaxY + -self.scalingCarousel.transform.ty
let newFormOriginY = safeAreaFrame.height - formHeight
let topOfFormMargin: CGFloat = 20
if (newFormOriginY - topOfFormMargin) < elementMaxYTransformRemoved {
// Form will overlap element - move carousel view to compensate
let oldToNewLocDist = (newFormOriginY - topOfFormMargin) - currentElementMaxY
let moveScreenBy = self.scalingCarousel.transform.ty + oldToNewLocDist
carouselOffset = CGAffineTransform(translationX: 0, y: moveScreenBy)
} else {
// Form will not overlap element - reset carousel view
carouselOffset = self.formDeactivate
}
return carouselOffset
}
And it is called as below:
func textViewDidChage() {
let backgorundTransform = calculateCarouselOffset(formHeight: currentElementFormHeight)
let modifyBackground = UIViewPropertyAnimator(duration: 0.2, curve: .linear, animations: {
self.scalingCarousel.transform = backgorundTransform
})
modifyBackground.startAnimation()
}
It looks like this is (possibly new?) built-in behaviour for text fields. I reproduced this both with a collection view controller and a view controller holding a collection view. The text field moves itself to visible like this:
I found this by adding a symbolic breakpoint on contentOffset and then making a field editable - there are a lot of calls before you get to this point because it's also adjusting things for the keyboard coming up.
Unfortunately in your case, I think the scroll view is moving the text field's visible bounds into the visible area, which means you're scrolling horizontally since the text field is off screen.
You can't override scrollTextFieldToVisibleIfNecessary as it is private API. There are probably some hacks you can do by overriding becomeFirstResponder but they seem quite likely to either not work, or break other things.
My VC starts with stackView attached with Align Bottom to Safe Area .
I have tabBar, but in the beginning is hidden tabBar.isHidden = true.
Later when the tabBar appears, it hides the stackView
So I need function that refresh constraints after tabBar.isHidden = false
When I start the app with tabBar.isHidden = false the stackView is shown properly.
Tried with every function like: stackView.needsUpdateConstraints() , updateConstraints() , setNeedsUpdateConstraints() without success.
Now I'm changing the bottom programatically, but when I switch the tabBarIndex and return to that one with changed bottom constraints it detects the tabBar and lifts the stackView under another view (which is not attached with constraints). Like is refreshing again the constraints. I'm hiding and showing this stackView with constrains on/off screen.
I need to refresh constraints after tabBar.isHidden = false, but the constraints don't detect the appearance of the tabBar.
As I mention switching between tabBars fixes the issue, so some code executes to detecting tabBar after the switch. Is anyone know this code? I tried with calling the methods viewDidLayoutSubviews and viewWillLayoutSubviews without success... Any suggestions?
This amateur approach fixed my bug... :D
tabBarController!.selectedIndex = 1
tabBarController!.selectedIndex = 0
Or with an extension
extension UITabBarController {
// Basically just toggles the tabs to fix layout issues
func forceConstraintRefresh() {
// Get the indices we need
let prevIndex = selectedIndex
var newIndex = 0
// Find an unused index
let items = viewControllers ?? []
find: for i in 0..<items.count {
if (i != prevIndex) {
newIndex = i
break find
}
}
// Toggle the tabs
selectedIndex = newIndex
selectedIndex = prevIndex
}
}
Usage (called when switching dark / light mode):
override func traitCollectionDidChange(_ previousTraitCollection: UITraitCollection?) {
super.traitCollectionDidChange(previousTraitCollection)
tabBarController?.forceConstraintRefresh()
}
If you want to update view's layout, you can try layoutIfNeeded() function.
after updating stackView constraints call this method:
stackView.superview?.layoutIfNeeded()
Apple's Human Interface Guidelines indicate that one should not mess around with the Tab Bar, which is why (I'm guessing) setting tabBar.isHidden doesn't properly update the rest of the view hierarchy.
Quick searching comes up with various UITabBarController extensions for showing / hiding the tab bar... but they all appear to push the tabBar down off-screen, rather than setting its .isHidden property. May or may not be suitable for your use.
I'm assuming from your comments that your VC in tab index 0 has a button (or some other action) to show / hide the tabBar?
If so, here is an approach that may do the job....
Add this enum in your project:
enum TabBarState {
case toggle, show, hide
}
and put this func in that view controller:
func showOrHideTabBar(state: TabBarState? = .toggle) {
if let tbc = self.tabBarController {
let b: Bool = (state == .toggle) ? !tbc.tabBar.isHidden : state == .hide
guard b != tbc.tabBar.isHidden else {
return
}
tbc.tabBar.isHidden = b
view.frame.size.height -= 0.1
view.setNeedsLayout()
view.frame.size.height += 0.1
}
}
You can call it with:
// default: toggles isHidden
showOrHideTabBar()
// toggles isHidden
showOrHideTabBar(state: .toggle)
// SHOW tabBar (if it's hidden)
showOrHideTabBar(state: .show)
// HIDE tabBar (if it's showing)
showOrHideTabBar(state: .hide)
I would expect that simply pairing .setNeedsLayout() with .layoutIfNeeded() after setting the tabBar's .isHidden property should do the job, but apparently not.
The quick frame height change (combined with .setNeedsLayout()) does trigger auto-layout, though, and the height change is not visible.
NOTE: This is the result of very brief testing, on one device and one iOS version. I expect it will work across devices and versions, but I have not done complete testing.
I have a UITableView with the same settings as a tableview on another view which decelerates correctly however this view is not.
It does work if I add :
self.tableView.bounces = true
self.tableView.alwaysBounceHorizontal = true
self.tableView.alwaysBounceVertical = true
But then the table will go off horizontally removing the alwaysBounceHorizontal will then stop the table from decelerating again and stop one the user stops touching.
Has anyone come across anything like this before, as I have the same content thats being displayed on a tableview on another view working normally.
Managed to just about fix this, it turned out it was caused by the UIRefreshControl
It feels like a bit of a hack but I have the table scroll deceleration working normally now by adding:
func scrollViewWillBeginDecelerating(scrollView: UIScrollView) {
self.refreshControl.removeFromSuperview()
}
func scrollViewDidScroll(scrollView: UIScrollView) {
if scrollView.contentOffset.y < 10{
self.tableView.addSubview(self.refreshControl)
}
}
I have two states of UIView:
I have animation between them using #IBaction for button:
#IBAction func tapped(sender: UIButton) {
flag = !flag
UIView.animateWithDuration(1.0) {
if self.flag {
NSLayoutConstraint.activateConstraints([self.myConstraint])
} else {
NSLayoutConstraint.deactivateConstraints([self.myConstraint])
}
self.view.layoutIfNeeded() //additional line
}
}
Animation is working only when I add additional line:
But when I remove that line, then my UIView is updated but without any animation, it happens immediately.
Why this line makes such difference? How is it working?
As I understand it, changing a constraint doesn't update the layout of your views right away. It queues the changes, and they only take place the next time the system updates layout.
By putting layoutIfNeeded inside your animation block it forces the view changes to be applied during the animation block. Otherwise they take place later, after the animation has been set up.
Is there a way I can set my scrollview not to clip its contents? (Which is a NSTextView)
I have a subclass of NSScrollView and want its content not to be clipped to its bounds.
I have tried overriding:
- (BOOL) wantsDefaultClipping{
return NO;
}
in MyScrollView and in MytextView without any effect.
In the iOS I would simply would do: myuitextView.clipsToBounds=NO; how can I do this in Cocoa?
EDIT
This is an example of what I want to achieve but in the mac
The scrollview is white, the scroller will never go outside its bounds but the text does since I did myuitextView.clipsToBounds=NO
See picture here
EDIT2
I wouldn't mind clip my view like #Josh suggested. But the real behaviour I would like to have can be explained with this picture:
Do you see the word *****EDIT***** that has being cut in the very first line?
I want the text not to be cut this way, rather I want it to completely appear and I will put a semitransparent image so it looks like it fades off when it's outside the frame.
Q: Why don't I simply put a semitransparent NSImageView on it so it looks like what I want?
A: Because 1.Scroller will be faded as well. Even if I correctly place the semitransparent NSImageView so the scroller looks fine, the cursor/caret will be able to go underneath the semitransparent NSImageView again it does not look good.
I would like to be able to control the area is clipped by NSClipView. I think that would solve my problem. Is there any alternative I have? maybe I can control the caret position or scrolling position through NSTextView so caret will never go near the top/bottom frame limits? or any work-around?
Any advice is appreciated.
Now that it's 2016 and we're using vibrant titlebars with full size content views, I'll add my thoughts to how someone might accomplish this. Hopefully, this will help anyone who came here looking for help on this, as it helped me.
This answers the question in regards to scrolling under the titlebar, but you could easily modify this technique to scroll under other things using the insets and caret position.
To get a scroll view (with or without an NSTextView inside of it) to scroll behind a titlebar, you can use:
// For transparent title.
window.titlebarAppearsTransparent = true
window.styleMask = window.styleMask | NSFullSizeContentViewWindowMask
window.appearance = NSAppearance(named: NSAppearanceNameVibrantLight)
This effectively overlays the titlebar of the NSWindow onto the window's contentView.
To constrain something to the top of the window without knowing the height of the titlebar:
// Make a constraint for SOMEVIEW to the top layout guide of the window:
let topEdgeConstraint = NSLayoutConstraint(
item: SOMEVIEW, attribute: NSLayoutAttribute.Top,
relatedBy: NSLayoutRelation.Equal,
toItem: window.contentLayoutGuide,
attribute: NSLayoutAttribute.Top, multiplier: 1.0, constant: 0.0)
// Turn the constraint on automatically:
topEdgeConstraint.active = true
This allows you to constrain the top of an element to the bottom of the titlebar (and or toolbar + any accessory views it may have). This was shown at WWDC in 2015: https://developer.apple.com/videos/play/wwdc2014/220/
To get the scrollview to scroll under the titlebar but show its scrollbars inside the unobscured part of the window, pin it to the top of the content view in IB or via code, which will cause it to be under the titlebar. Then, tell it to automatically update it's insets:
scrollView.automaticallyAdjustsContentInsets = true
Finally, you can subclass your window and handle the cursor/caret position. There is a presumed bug (or developer error on my part) that doesn't make the scrollview always scroll to the cursor/caret when it goes above or below the content insets of the scrollview.
To fix this, you must manually find the caret position and scroll to see it when the selection changes. Forgive my awful code, but it seems to get the job done. This code belongs in an NSWindow subclass, so self is referring to the window.
// MARK: NSTextViewDelegate
func textViewDidChangeSelection(notification: NSNotification) {
scrollIfCaretIsObscured()
textView.needsDisplay = true // Prevents a selection rendering glitch from sticking around
}
// MARK: My Scrolling Functions
func scrollIfCaretIsObscured() {
let rect = caretRectInWindow()
let y: CGFloat = caretYPositionInWindow() - rect.height
// Todo: Make this consider the text view's ruler height, if present:
let tbHeight: CGFloat
if textView.rulerVisible {
// Ruler is shown:
tbHeight = (try! titlebarHeight()) + textViewRulerHeight
} else {
// Ruler is hidden
tbHeight = try! titlebarHeight()
}
if y <= tbHeight {
scrollToCursor()
}
}
func caretYPositionInWindow() -> CGFloat {
let caretRectInWin: NSRect = caretRectInWindow()
let caretYPosInWin: CGFloat = self.contentView!.frame.height - caretRectInWin.origin.y
return caretYPosInWin
}
func caretRectInWindow() -> CGRect {
// My own version of something based off of an old, outdated
// answer on stack overflow.
// Credit: http://stackoverflow.com/questions/6948914/nspopover-below-caret-in-nstextview
let caretRect: NSRect = textView.firstRectForCharacterRange(textView.selectedRange(), actualRange: nil)
let caretRectInWin: NSRect = self.convertRectFromScreen(caretRect)
return caretRectInWin
}
/// Scrolls to the current caret position inside the text view.
/// - Parameter textView: The specified text view to work with.
func scrollToCursor() {
let caretRectInScreenCoords = textView.firstRectForCharacterRange(textView.selectedRange(), actualRange: nil)
let caretRectInWindowCoords = self.convertRectFromScreen(caretRectInScreenCoords)
let caretRectInTextView = textView.convertRect(caretRectInWindowCoords, fromView: nil)
textView.scrollRectToVisible(caretRectInTextView)
}
enum WindowErrors: ErrorType {
case CannotFindTitlebarHeight
}
/// Calculates the combined height of the titlebar and toolbar.
/// Don't try this at home.
func titlebarHeight() throws -> CGFloat {
// Try the official way first:
if self.titlebarAccessoryViewControllers.count > 0 {
let textViewInspectorBar = self.titlebarAccessoryViewControllers[0].view
if let titlebarAccessoryClipView = textViewInspectorBar.superview {
if let view = titlebarAccessoryClipView.superview {
if let titleBarView = view.superview {
let titleBarHeight: CGFloat = titleBarView.frame.height
return titleBarHeight
}
}
}
}
throw WindowErrors.CannotFindTitlebarHeight
}
Hope this helps!
I would simply try to observe the document view's frame and match the scroll view's frame when the document resizes.
This is a little hairy. AFAIK, NSViews can't draw outside their own frame. At any rate I've never seen it done, and I was somewhat surprised when I realized that UIView allows it by default. But what you probably want to do here is not manipulate clipping rectangles (doing any such thing inside NSScrollView will probably not do what you want or expect), but instead try to cover up the vertically-truncated text lines with either layers or views that are the same color as the background. Perhaps you could subclass NSClipView and override viewBoundsChanged: and/or viewFrameChanged: in order to notice when the text view is being shifted, and adjust your "shades" accordingly.
You might consider using a translucent layer to achieve this appearance, without actually drawing outside your view. I'm not certain of the rules on iOS, but on the Mac, a view drawing outside its bounds can cause interference with surrounding drawing.
However, you can set the clipping region to be whatever you like inside your scroll view subclass's drawRect: using -[NSBezierPath setClip:]:
- (void)drawRect:(NSRect)dirtyRect {
[NSGraphicsContext saveGraphicsState];
[[NSBezierPath bezierPathWithRect:[[self documentView] frame]] setClip];
//...
[NSGraphicsContext restoreGraphicsState];
}
It might be possible (since you asked) to use this code in an NSClipView subclass, but there's not much info about that, and I think you may have a hard time making it interact properly with its scroll view. If it were me, I'd try subclassing NSScrollView first.