I am building a chat. Everything seem to be quite ok but I bumped into sort of 'buggy' problem.
i got UIViewController with UITextView bar for entering message and UITableView.
They are in this constraint: "V:|-(64)-[chatTable][sendMessageBar]-(keyboard)-|".
When the keyboard is not out - the constant of this constraint is 0. and after keyboard is out - i increase the constant to keyboard height.
when the keyboard is not out:
self.table.contentSize = (375.0,78.5)
self.table.bounds = (0.0,-490.0,375.0,568.5)
self.table.frame = (0.0,64.0,375.0,568.5)
self.table.subviews[0].frame (UITableViewWrapperView) = (0.0,0.0,375.0,568.5)
self.table.subviews[0].frame (UITableViewWrapperView) = (0.0,0.0,375.0,568.5)
and when the keyboard comes out:
self.table.contentSize = (375.0,78.5)
self.table.bounds = (0.0,-274.0,375.0,352.5
self.table.frame = (0.0,64.0,375.0,352.5)
self.table.subviews[0].frame (UITableViewWrapperView) = (0.0,-137.5,375.0,137.5)
self.table.subviews[0].frame (UITableViewWrapperView) = (0.0,0.0,375.0,137.5)
So the UITableViewWrapperView, after I increase constraints constant, differs in size to its superview - UITableView. Is there a way to fix this ? I would assume that UITableViewWrapperView would change its frame and bounds according to UITableView but it does not.
Any ideas where is the problem or how could I work around it ?
ADDING:
After some more research - it seems that it happens somewhere between viewWillLayoutSubviews and viewDidLayoutSubviews. It is kinda weird tho:
override func viewWillLayoutSubviews() {
println("WrapperView Frame :991: \(self.table.subviews[0].frame)") \\ WrapperView Frame :991: (0.0,0.0,375.0,568.5)
super.viewWillLayoutSubviews()
println("WrapperView Frame :992: \(self.table.subviews[0].frame)") \\ WrapperView Frame :992: (0.0,0.0,375.0,568.5)
}
override func viewDidLayoutSubviews() {
println("WrapperView Frame :6: \(self.table.subviews[0].frame)") \\ WrapperView Frame :6: (0.0,-137.5,375.0,137.5)
super.viewDidLayoutSubviews()
println(">> viewDidLayoutSubviews")
}
So it seems that something happens there that messes up the UITableViewWrapperView
The following fixed it for me:
func fixTableViewInsets() {
let zContentInsets = UIEdgeInsetsZero
tableView.contentInset = zContentInsets
tableView.scrollIndicatorInsets = zContentInsets
}
override func viewWillLayoutSubviews() {
super.viewWillLayoutSubviews()
fixTableViewInsets()
}
I discovered that at viewWillAppear() that the insets were all 0. But at viewDidAppear(), they had been modified to apparently offset for navigation bar, etc. This makes the UITableViewWrapperView different from the UITableView.
I changed the insets in its own routine so that it was easier to experiment with calling it from different places. The viewWillLayoutSubviews() let it get changed before being presented - placing the change in viewDidAppear() caused the table to jerk.
I ran into this today and while the fix suggested by #anorskdev works nicely, it seems that the root cause of the issue is the automaticallyAdjustsScrollViewInsets property of UIViewController, which is true by default. I turned it off in my storyboard and the problem went away. Look for the "Adjust Scroll View Insets" checkbox in the View Controller inspector and make sure it's unchecked.
It seems that it is a bug (fighting with this bug took all day for me)
Finally this workaround helped:
for (UIView *subview in tableView.subviews)
{
if ([NSStringFromClass([subview class]) isEqualToString:#"UITableViewWrapperView"])
{
subview.frame = CGRectMake(0, 0, tableView.bounds.size.width, tableView.bounds.size.height);
}
}
After small investigation I have found this solution with setting all the safeAreaInsets and layoutMargins on the UITableView to zero:
Swift 4 snipset:
class CustomTableView: UITableView {
override var safeAreaInsets: UIEdgeInsets {
get {
return .zero
}
}
override var layoutMargins: UIEdgeInsets {
get {
return .zero
}
set {
super.layoutMargins = .zero
}
}
}
The main problem is safeAreaInsets introduced in tvOS 11.0 - the UITableViewWrapperView just took the properties from the parent view (UITableView) and renders the content with safeAreaInsets.
I was facing the same issue on tvOS 11.3, and neither of suggestions related with zero insets or scroll disable did the job, except looping through tableView's subviews and setting the UITableViewWrapperView's frame to the tableView's frame.
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
for view in tableView.subviews {
if String(describing: type(of: view)) == "UITableViewWrapperView" {
view.frame = CGRect(x: 0, y: 0, width: tableView.bounds.size.width, height: tableView.bounds.size.height)
}
}
}
In iOS 11 UITableViewWrapperView has gone, so this problem may occur only on later iOS versions. I faced it on iOS10 when I pushed custom UIViewController in UINavigationController stack.
So, the solution is to override property automaticallyAdjustsScrollViewInsets in custom view controller like this:
override var automaticallyAdjustsScrollViewInsets: Bool {
get {
return false
}
set {
}
}
Objective C version of this answer given by anorskdev
- (void) viewWillLayoutSubviews {
[super viewWillLayoutSubviews];
[tableView setContentInset:UIEdgeInsetsZero];
[tableView setScrollIndicatorInsets:UIEdgeInsetsZero];
}
edit: Turning off automaticallyAdjustsScrollViewInsets on the hosting ViewController, as suggested by Steve Roy in this answer, also worked and is the one I went with, as it seems cleaner to disable the behaviour rather than correcting it afterwards.
Related
I am updating my app to adapt it for iPhone X. All views work fine by now except one. I have a view controller that presents a custom UIView that covers the whole screen. Before I was using UIScreen.main.bounds to find out the size of the view before all layout was done (I need it for putting the correct itemSize for a collectionView). I thought that now I could do something like
UIScreen.main.bounds.size.height - safeAreaInsets.bottom to get the right usable size. The problem is, safeAreaInsets returns (0,0,0,0) trying on an iPhone X (Simulator). Any ideas? In other views, I get the right numbers for safeAreaInsets.
Thank you!
I recently had a similar problem where the safe area insets are returning (0, 0, 0, 0) as soon as viewDidLoad is triggered. It seems that they are set fractionally later than the rest of the view loading.
I got round it by overriding viewSafeAreaInsetsDidChange and doing my layout in that instead:
override func viewSafeAreaInsetsDidChange() {
// ... your layout code here
}
I already figure out the solution: I was doing all the implementation in the init of the view. safeAreaInsets has the correct size in layoutSubviews()
I've run into this issue too trying to move up views to make way for the keyboard on the iPhone X. The safeAreaInsets of the main view are always 0, even though I know the subviews have been laid out at this point as the screen has been drawn. A work around I found, as and mentioned above, is to get the keyWindow and check its safe area insets instead.
Obj-C:
CGFloat bottomInset = [UIApplication sharedApplication].keyWindow.safeAreaInsets.bottom;
Swift:
let bottomInset = UIApplication.shared.keyWindow?.safeAreaInsets.bottom
You can then use this value to adjust constraints or view frames as required.
I have a view which is a subview inside another view.
I found that I can't get safeAreaInsets correctly, it always return 0, in that view on iPhoneX even if I put it in layoutSubviews.
The final solution is I use following UIScreen extension to detect safeAreaInsets which can work like a charm.
extension UIScreen {
func widthOfSafeArea() -> CGFloat {
guard let rootView = UIApplication.shared.keyWindow else { return 0 }
if #available(iOS 11.0, *) {
let leftInset = rootView.safeAreaInsets.left
let rightInset = rootView.safeAreaInsets.right
return rootView.bounds.width - leftInset - rightInset
} else {
return rootView.bounds.width
}
}
func heightOfSafeArea() -> CGFloat {
guard let rootView = UIApplication.shared.keyWindow else { return 0 }
if #available(iOS 11.0, *) {
let topInset = rootView.safeAreaInsets.top
let bottomInset = rootView.safeAreaInsets.bottom
return rootView.bounds.height - topInset - bottomInset
} else {
return rootView.bounds.height
}
}
}
I try to use "self.view.safeAreaInset" in a view controller. First, it is a NSInsetZero when I use it in the controller's life cycle method "viewDidLoad", then I search it from the net and get the right answer, the log is like:
ViewController loadView() SafeAreaInsets :UIEdgeInsets(top: 0.0, left: 0.0, bottom: 0.0, right: 0.0)
ViewController viewDidLoad() SafeAreaInsets :UIEdgeInsets(top: 0.0, left: 0.0, bottom: 0.0, right: 0.0)
ViewController viewWillAppear() SafeAreaInsets :UIEdgeInsets(top: 0.0, left: 0.0, bottom: 0.0, right: 0.0)
ViewController viewDidLayoutSubviews() SafeAreaInsets :UIEdgeInsets(top: 44.0, left: 0.0, bottom: 34.0, right: 0.0)
ViewController viewDidAppear() SafeAreaInsets :UIEdgeInsets(top: 44.0, left: 0.0, bottom: 34.0, right: 0.0)
so you can choice the right method that you need the safeAreaInset and use it!
Swift iOS 11,12,13+
var insets : UIEdgeInsets = .zero
override func viewDidLoad() {
super.viewDidLoad()
insets = UIApplication.shared.delegate?.window??.safeAreaInsets ?? .zero
//Or you can use this
insets = self.view.safeAreaInsets
}
In my case I was adding a UICollectionView inside viewDidLoad()
collectionView = UICollectionView(frame: view.safeAreaLayoutGuide.layoutFrame, collectionViewLayout: createCompositionalLayout())
Unfortunately at this stage safeAreaLayoutGuide is still zero.
I solved it by adding:
override func viewDidLayoutSubviews() {
collectionView.frame = view.safeAreaLayoutGuide.layoutFrame
}
the viewDidAppear(_:) method of the container view controller that extends the safe area of its embedded child view controller to account for the views in .
Make your modifications in this method because the safe area insets for a view are not accurate until the view is added to a view hierarchy.
override func viewDidAppear(_ animated: Bool) {
if (#available(iOS 11, *)) {
var newSafeArea = view.safeAreaInsets
// Adjust the safe area to accommodate
// the width of the side view.
if let sideViewWidth = sideView?.bounds.size.width {
newSafeArea.right += sideViewWidth
}
// Adjust the safe area to accommodate
// the height of the bottom view.
if let bottomViewHeight = bottomView?.bounds.size.height {
newSafeArea.bottom += bottomViewHeight
}
// Adjust the safe area insets of the
// embedded child view controller.
let child = self.childViewControllers[0]
child.additionalSafeAreaInsets = newSafeArea
}
}
I've come across the same problem. In my case the view I'm inserting would be sized correctly after calling view.layoutIfNeeded(). The view.safeAreaInsets was set after this, but only the top value was correct. The bottom value was still 0 (this on an iPhone X).
While trying to figure out at what point the safeAreaInsets are set correctly, I've added a breakpoint on the view's safeAreaInsetsDidChange() method. This was being called multiple times, but only when I saw CALayer.layoutSublayers() in the backtrace the value had been set correctly.
So I've replaced view.layoutIfNeeded() by the CALayer's counterpart view.layer.layoutIfNeeded(), which resulted in the safeAreaInsets to be set correctly right away, thus solving my problem.
TL;DR
Replace
view.layoutIfNeeded()
by
view.layer.layoutIfNeeded()
[UIApplication sharedApplication].keyWindow.safeAreaInsets return none zero
Just try self.view.safeAreaInsets instead of UIApplication.shared.keyWindow?.safeAreaInsets
Safe area insets seems to not fill on iOS 11.x.x devices when requested via application keyWindow.
View layout is never guaranteed until layoutSubviews or viewDidLayoutSubviews. Never rely on sizes before these lifecycle methods. You will get inconsistent results if you do.
To calculate safe area safeAreaInsets, try to obtain it in viewWIllAppear(), as in didLoad() the view have not been formed.
You will have the correct inset in willAppear!
In case you cannot subclass, you can use this UIView extension.
It gives you an API like this:
view.onSafeAreaInsetsDidChange = { [unowned self] in
self.updateSomeLayout()
}
The extension adds an onSafeAreaInsetsDidChange property using object association. Then swizzles the UIView.safeAreaInsetsDidChange() method to call the closure (if any).
extension UIView {
typealias Action = () -> Void
var onSafeAreaInsetsDidChange: Action? {
get {
associatedObject(for: "onSafeAreaInsetsDidChange") as? Action
}
set {
Self.swizzleSafeAreaInsetsDidChangeIfNeeded()
set(associatedObject: newValue, for: "onSafeAreaInsetsDidChange")
}
}
static var swizzled = false
static func swizzleSafeAreaInsetsDidChangeIfNeeded() {
guard swizzled == false else { return }
swizzle(
method: "safeAreaInsetsDidChange",
originalSelector: #selector(originalSafeAreaInsetsDidChange),
swizzledSelector: #selector(swizzledSafeAreaInsetsDidChange),
for: Self.self
)
swizzled = true
}
#objc func originalSafeAreaInsetsDidChange() {
// Original implementaion will be copied here.
}
#objc func swizzledSafeAreaInsetsDidChange() {
originalSafeAreaInsetsDidChange()
onSafeAreaInsetsDidChange?()
}
}
It uses some helpers (see NSObject+Extensions.swift and NSObject+Swizzle.swift), but you don't really need it if you use sizzling and object association APIs directly.
When I have text that does not fill the UITextView, it is scrolled to the top working as intended. When there is more text than will fit on screen, the UITextView is scrolled to the middle of the text, rather than the top.
Here are some potentially relevant details:
In viewDidLoad to give some padding on top and bottom of UITextView:
self.mainTextView.textContainerInset = UIEdgeInsetsMake(90, 0, 70, 0);
The UITextView uses auto layout to anchor it 20px from top, bottom and each side of the screen (done in IB) to allow for different screen sizes and orientations.
I can still scroll it with my finger once its loaded.
EDIT
I found that removing the auto layout constraints and then fixing the width only seems to fix the issue, but only for that screen width.
add the following function to your view controller class...
Swift 3
override func viewDidLayoutSubviews() {
self.mainTextView.setContentOffset(.zero, animated: false)
}
Swift 2.1
override func viewDidLayoutSubviews() {
self.mainTextView.setContentOffset(CGPointZero, animated: false)
}
Objective C
- (void)viewDidLayoutSubviews {
[self.mainTextView setContentOffset:CGPointZero animated:NO];
}
UITextView is a subclass of UIScrollView, so you can use its methods. If all you want to do is ensure that it's scrolled to the top, then wherever the text is added try:
[self.mainTextView setContentOffset:CGPointZero animated:NO];
EDIT: AutoLayout with any kind of scrollview gets wonky fast. That setting a fixed width solves it isn't surprising. If it doesn't work in -viewDidLayoutSubviews then that is odd. Setting a layout constraint manually may work. First create the constraints in IB:
#property (weak, nonatomic) IBOutlet NSLayoutConstraint *textViewWidthConstraint;
#property (weak, nonatomic) IBOutlet NSLayoutConstraint *textViewHeightConstraint;
then in the ViewController
-(void)updateViewConstraints {
self.textViewWidthConstraint.constant = self.view.frame.size.width - 40.0f;
self.textViewHeightConstraint.constant = self.view.frame.size.height - 40.0f;
[super updateViewConstraints];
}
May still be necessary to setContentOffset in -viewDidLayoutSubviews.
(Another method would be to create a layout constraint for "'equal' widths" and "'equal' heights" between the textView and its superView, with a constant of "-40". It's only 'equal' if the constant is zero, otherwise it adjusts by the constant. But because you can only add this constraint to a view that constraints both views, you can't do this in IB.)
You may ask yourself, if I have to do this, what's the point of AutoLayout? I've studied AutoLayout in depth, and that is an excellent question.
Swift
self.textView.scrollRangeToVisible(NSMakeRange(0, 0))
Objective-C
[self.textView scrollRangeToVisible:(NSMakeRange(0, 0))];
i had same issue! Reset to suggested constrains and just put (y offset)
#IBOutlet weak var textContent: UITextView!
override func viewDidLoad() {
textContent.scrollsToTop = true
var contentHeight = textContent.contentSize.height
var offSet = textContent.contentOffset.x
var contentOffset = contentHeight - offSet
textContent.contentOffset = CGPointMake(0, -contentOffset)
}
For iOS9 and later the textview even on viewWillAppear: is coming with CGRect(0,0,1000,1000). In order for this to work you have to call in viewWillAppear:
[self.view setNeedsLayout];
[self.view layoutIfNeeded];
// * Your code here
After that the textview will have correct CGRect data and you can perform any scrolling operation you may need.
The problem with putting code in viewDidLayoutSubviews and viewWillLayoutSubviews is that these methods are called a lot (during device rotation, resizing views etc ...). If you're reading something from text view, and you rotate the device, you expect that the part of the content you're viewing stays on screen. You do not expect that it scrolls back to top.
Instead of scrolling the content to top, try to keep text view's scrollEnabled property set to NO (false), and turn it back on in viewDidAppear.
If you don't wanna mess with constraints:
override func updateViewConstraints() {
super.updateViewConstraints()
}
override func viewDidLayoutSubviews() {
self.textLabel.setContentOffset(CGPointZero, animated: false)
}
This is an interesting bug. In our project, this is only occurring on devices with an iPhone 5-size screen. It appears that the textview contentOffset changes at some point during the view controller lifecycle. In viewDidLoad and viewWillAppear the textview's contentOffset is 0,0, and by viewDidAppear it's changed. You can see it happening in viewWillLayoutSubviews. Constraints appear to be set up correctly.
This will ensure you don't call a scrolling method unless it's needed:
if textView.contentOffset.y > 0 {
textView.contentOffset = CGPoint(x: 0, y: 0)
// Or use scrollRectToVisible, scrollRangeToVisible, etc.
}
Swift
override func viewDidLoad() {
super.viewDidLoad()
textView.isScrollEnabled = false
}
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
textView.isScrollEnabled = true
}
For me this works in a different way, I tried all things mentioned above but none of the worked in func viewWillAppear(_ animated: Bool). Which eventually makes textView scrolled up, and in func viewDidAppear(_ animated: Bool) it would scroll after screen appeared.
Below worked for me but got some constraint related issue with keyboard up and down.
override func viewDidLayoutSubviews() {
self.textView.setContentOffset(.zero, animated: false)
}
Below worked as expectation:
override func viewDidLoad() {
super.viewDidLoad()
self.textView.scrollsToTop = true
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
self.view.layoutIfNeeded()
self.textView.setContentOffset(.zero, animated: false)
}
David Rectors answer in Objective C:
#import "TopTextView.h"
#implementation TopTextView
bool scrolled = NO;
- (void) layoutSubviews
{
[super layoutSubviews];
if (!scrolled) {
[self setContentOffset:CGPointMake(0, 0) animated:NO];
scrolled = YES;
}
}
#end
It seems like a terrible idea to handle this issue in code in the view controller because: A. The view controller isn't making any mistake or doing anything wrong, and B, if you have more than one view controller with a wrongly scrolled text view, you end up with redundant code. The solution should be to write code that exists in the text view class. My solution works with Interface Builder where I simply select a custom class for the UITextView and use this class:
import Foundation
import UIKit
class TopTextView: UITextView {
var scrolled = false
override func layoutSubviews() {
super.layoutSubviews()
if scrolled { return }
setContentOffset(.zero, animated: false)
scrolled = true
}
}
This worked for me. I happen to have a view controller with a child view with a UITextView as a child of that view, not with a UITextView as the child of the view controller. I don't know how well this works if the text view is under top or bottom bars but since no edge insets are touched, this should work.
In my case I had to do it like this:
textView.setContentOffset(CGPoint(x: 0, y: -self.textView.adjustedContentInset.top), animated: false)
because the texview was underneath the navigation bar and had an adjusted inset
I'll get right to it. I have a UItextView placed in my view that when needs to scroll to see all the text (when a lot of text is present in the textView) the textView starts in the middle of the text sometimes and the bottom of the text other times.
Editing is not enabled on the textView. I need a way to force the textView to start at the top, every time. I saw some questions somewhat like this where other people used a content offset, but I do not really know how that works or if it would even be applicable here.
Thanks for your help.
That did the trick for me!
Objective C:
[self.textView scrollRangeToVisible:NSMakeRange(0, 0)];
Swift:
self.textView.scrollRangeToVisible(NSMakeRange(0, 0))
Swift 2 (Alternate Solution)
Add this override method to your ViewController
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
textView.setContentOffset(CGPointZero, animated: false)
}
Swift 3 & 4 (syntax edit)
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
textView.contentOffset = .zero
}
All of the answers above did not work for me. However, the secret turns out to be to implement your solution within an override of viewDidLayoutSubviews, as in:
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
welcomeText.contentOffset = .zero
}
HTH :)
In Swift 2
You can use this to make the textView start from the top:
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
myTextView.setContentOffset(CGPointZero, animated: false)
}
Confirmed working in Xcode 7.2 with Swift 2
Try this below code -
if ( [self respondsToSelector:#selector(setAutomaticallyAdjustsScrollViewInsets:)]){
self.automaticallyAdjustsScrollViewInsets = NO;
}
Or you can also set this property by StoryBoard -
Select ViewController then select attributes inspector now unchecked Adjust Scroll View Insets.
For Swift >2.2, I had issues with iOS 8 and iOS 9 using above methods as there are no single answer that works so here is what I did to make it work for both.
override func viewWillAppear(animated: Bool) {
super.viewWillAppear(animated)
if #available(iOS 9.0, *) {
textView.scrollEnabled = false
}
self.textView.scrollRangeToVisible(NSMakeRange(0, 0))
}
override func viewDidAppear(animated: Bool) {
super.viewDidAppear(animated)
if #available(iOS 9.0, *) {
textView.scrollEnabled = true
}
}
Update your UINavigationBar's translucent property to NO:
self.navigationController.navigationBar.translucent = NO;
This will fix the view from being framed underneath the navigation bar and status bar.
If you have to show and hide the navigation bar, then use below code in your viewDidLoad
if ([self respondsToSelector:#selector(edgesForExtendedLayout)])
self.edgesForExtendedLayout = UIRectEdgeNone; // iOS 7 specific
Hope this helps.
Xcode 7.2 7c68; IOS 9.1
My ViewController which contains UITextView is complicated, and changed a lot during the project (IDE version changed maybe 2~3 times too).
I've tried all above solutions, if you encounter the same issue, be PATIENT.
There are three possible 'secret codes' to solve:
textView.scrollEnabled = false
//then set text
textView.scrollEnabled = true
textView.scrollRangeToVisible(NSMakeRange(0, 0))
textView.setContentOffset(CGPointZero, animated: false)
And there are two places you can put those codes in:
viewDidLoad()
viewDidLayoutSubviews()
Combine them, you'll get 3*2=6 solutions, the correct combination depends on how complicated you ViewController is (Believe me, after delete just a view above textView, I need to find a new combination).
And I found that:
When put 'secret codes' in viewDidLayoutSubviews(), but textView.text = someStrings in viewDidLoad(), the content in textView will 'shake' sometimes. So, put them in the same place.
Last word: try ALL combinations, this is how I solve this stupid bug more than three times during two months.
With a lot of testing, i found must add below in viewWillLayoutSubviews() function to make sure the UITextView show up from the very beginning:
override func viewWillLayoutSubviews() {
super.viewWillLayoutSubviews()
textViewTerms.scrollRangeToVisible(NSMakeRange(0, 0))
}
UITextView scrolling seems to be a problem to a lot of people. Gathering from the answers here around (especially this) and the Apple Developer documentation, using some of my own wit, here is a solution that works for me. You can modify the code to suit your needs.
My use case is as follows: the same UITextView is used for different purposes, displaying varying content in different circumstances. What I want is that when the content changes, the old scroll position is restored, or at times, scrolled to the end. I don't want too much animation when this is done. Especially I don't want the view to animate like all the text was new. This solution first restores the old scroll position without animation, then scrolls to the end animated, if so desired.
What you need to do (or should I say can do) is extend UITextView as follows:
extension UITextView {
func setText(text: String, storedOffset: CGPoint, scrollToEnd: Bool) {
self.text = text
let delayInSeconds = 0.001
let popTime: dispatch_time_t = dispatch_time(DISPATCH_TIME_NOW, Int64(delayInSeconds * Double(NSEC_PER_SEC)))
dispatch_after(popTime, dispatch_get_main_queue(), {
self.setContentOffset(storedOffset, animated: false)
if scrollToEnd && !text.isEmpty {
let popTime: dispatch_time_t = dispatch_time(DISPATCH_TIME_NOW, Int64(delayInSeconds * Double(NSEC_PER_SEC)))
dispatch_after(popTime, dispatch_get_main_queue(), {
self.scrollRangeToVisible(NSMakeRange(text.lengthOfBytesUsingEncoding(NSUTF8StringEncoding) - 1, 0))
})
}
})
}
}
What this does is it updates the text, then uses a stored value of the UITextView.contentOffset property (or anything you pass as a parameter), and sets the offset of the view accordingly. If desired, after this, it scrolls to the end of the new, potentially changed content.
I'm new to iOS programming and I don't know why it works so well it does, if someone has some information on this it would be nice to know. Also the approach may not be perfect so I'm open to improvement ideas as well.
And of course thanks to NixonsBack for posting the answer behind the link above.
My first post :), cheers!
Put this one line of code in ViewDidLoad
self.automaticallyAdjustsScrollViewInsets = false
The following code should give you effect you want.
[self.scrollView setContentOffset:CGPointMake(0, -self.scrollView.contentInset.top) animated:YES];
You'll need to replace "self.scrollView" with the name of your scroll view. You should put this code in after you've set the text of the scroll view.
This worked for me:
override func viewWillLayoutSubviews() {
super.viewWillLayoutSubviews()
textView.scrollRectToVisible(CGRect(origin: CGPointZero, size: CGSizeMake(1.0, 1.0)), animated: false)
}
This worked for me with Xcode 8.3.3:
-(void)viewWillLayoutSubviews
{
[super viewWillLayoutSubviews];
[self.txtQuestion scrollRangeToVisible:NSMakeRange(0, 0)];
}
Create an outlet for your UITextView in the ViewController.swift file. In the ViewDidLoad section put the following:
Swift:
self.textView.contentOffset.y = 0
I have tried:
self.textView.scrollRangeToVisible(NSMakeRange(0, 0))
I translated zeeple's answer to MonoTouch/Xamarin (C#).
public override void ViewDidLayoutSubviews()
{
base.ViewDidLayoutSubviews();
myForm.SetContentOffset(new CoreGraphics.CGPoint(0,0), animated: false);
}
I had to implement two answers here to get my view working as I want:
From Juan David Cruz Serrano:
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
textView.setContentOffset(CGPoint.zero, animated: false)
}
And from Murat Yasar:
automaticallyAdjustsScrollViewInsets = false
This gave a UITextView that loads with the scroll at the very top and where the insets are not changed once scrolling starts. Very strange that this is not the default behaviour.
To force the textView to start at the top every time, use the following code:
Swift 4.2:
override func viewDidLayoutSubviews() {
textView.setContentOffset(CGPoint(x: 0, y: 0), animated: false)
}
Objective-C:
- (void)viewDidLayoutSubviews {
[self.yourTextView setContentOffset:CGPointZero animated:NO];
}
Swift 4.2 & Swift 5
set content offset both before and after setting the text. (on the main Thread)
let animation = false //or whatever you want
self.mainTextView.setContentOffset(.zero, animated: animation)
self.mainTextView.attributedText = YOUR_ATTRIBUTED_TEXT
self.mainTextView.setContentOffset(.zero, animated: animation)
In my case I was loading a textView in a Custom tableview cell. Below is what I did to make sure the text in a textview loads at the top of the text in my textview in my custom cell.
1.) In storyboard, set the textview ScrollEnabled = false by unchecking the button.
2.) You set the isScrollEnabled to true on the textview after the view loads. I set mine in a small delay like below:
override func awakeFromNib() {
super.awakeFromNib()
let when = DispatchTime.now() + 1
DispatchQueue.main.asyncAfter(deadline: when){
self.textView.isScrollEnabled = true
}
}
Regardless, if you are in my situation or not, try setting scrollEnabled to false and then when the view loads, set scrollEnabled to true.
Long time lurker - first time poster!
I am having an issue while recreating a bar with a UITextView like WhatsApp does it.
I am using a custom UIView subclass, and lazily instantiating it on:
- (UIView *)inputAccessoryView
and returning YES on:
- (BOOL)canBecomeFirstResponder
Now, I want to change the size of the inputAccessoryView when the UITextView grows in size. On iOS 7, I would simply change the size of the frame of said view - and not it's origin -, and then call reloadInputViews and it would work: the view would be moved upwards so that it is fully visible above the keyboard.
On iOS 8, however, this does not work. The only way to make it work is to also change the origin of the frame to a negative value. This would be fine, except it creates some weird bugs: for example, the UIView returns to the 'original' frame when entering any text.
Is there something I am missing? I am pretty certain WhatsApp uses inputAccessoryView because of the way they dismiss the keyboard on drag - only in the latest version of the app.
Please let me know if you can help me out! Or if there is any test you would like me to run!
Thank you! :)
BTW, here is the code I am using to update the height of the custom UIView called composeBar:
// ComposeBar frame size
CGRect frame = self.composeBar.frame;
frame.size.height += heightDifference;
frame.origin.y -= heightDifference;
self.composeBar.frame = frame;
[self.composeBar.textView reloadInputViews]; // Tried with this
[self reloadInputViews]; // and this
Edit: full source code is available # https://github.com/manuelmenzella/SocketChat-iOS
I've been banging my head against the wall on this one for quite some time, as the behavior changed from iOS 7 to iOS 8. I tried everything, until the most obvious solution of all worked for me:
inputAccessoryView.autoresizingMask = UIViewAutoresizingFlexibleHeight;
duh!
To sum up JohnnyC's answer: set your inpitAccessoryView's autoresizingMask to .flexibleHeight, calculate its intrinsicContentSize and let the framework do the rest.
Full code, updated for Swift 3:
class InputAccessoryView: UIView, UITextViewDelegate {
let textView = UITextView()
override var intrinsicContentSize: CGSize {
// Calculate intrinsicContentSize that will fit all the text
let textSize = textView.sizeThatFits(CGSize(width: textView.bounds.width, height: CGFloat.greatestFiniteMagnitude))
return CGSize(width: bounds.width, height: textSize.height)
}
override init(frame: CGRect) {
super.init(frame: frame)
// This is required to make the view grow vertically
autoresizingMask = .flexibleHeight
// Setup textView as needed
addSubview(textView)
textView.translatesAutoresizingMaskIntoConstraints = false
addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "H:|[textView]|", options: [], metrics: nil, views: ["textView": textView]))
addConstraints(NSLayoutConstraint.constraints(withVisualFormat: "V:|[textView]|", options: [], metrics: nil, views: ["textView": textView]))
textView.delegate = self
// Disabling textView scrolling prevents some undesired effects,
// like incorrect contentOffset when adding new line,
// and makes the textView behave similar to Apple's Messages app
textView.isScrollEnabled = false
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
// MARK: UITextViewDelegate
func textViewDidChange(_ textView: UITextView) {
// Re-calculate intrinsicContentSize when text changes
invalidateIntrinsicContentSize()
}
}
The issue is that in iOS 8, an NSLayoutConstraint that sets the inputAccessoryView's height equal to its initial frame height is installed automatically. In order to fix the layout problem, you need to update that constraint to the desired height and then instruct your inputAccessoryView to lay itself out.
- (void)changeInputAccessoryView:(UIView *)inputAccessoryView toHeight:(CGFloat)height {
for (NSLayoutConstraint *constraint in [inputAccessoryView constraints]) {
if (constraint.firstAttribute == NSLayoutAttributeHeight) {
constraint.constant = height;
[inputAccessoryView layoutIfNeeded];
break;
}
}
}
Here's a complete, self-contained solution (thanks #JohnnyC and #JoãoNunes for pointing me in the right direction, #stigi for explaining how to animate intrinsicContent changes):
class InputAccessoryView: UIView {
// InputAccessoryView is instantiated from nib, but it's not a requirement
override func awakeFromNib() {
super.awakeFromNib()
autoresizingMask = .FlexibleHeight
}
override func intrinsicContentSize() -> CGSize {
let exactHeight = // calculate exact height of your view here
return CGSize(width: UIViewNoIntrinsicMetric, height: exactHeight)
}
func somethingDidHappen() {
// invalidate intrinsic content size, animate superview layout
UIView.animateWithDuration(0.2) {
self.invalidateIntrinsicContentSize()
self.superview?.setNeedsLayout()
self.superview?.layoutIfNeeded()
}
}
}
100% working and very simple solution is to enumerate all constraints and set new height value. Here is some C# code (xamarin):
foreach (var constraint in inputAccessoryView.Constraints)
{
if (constraint.FirstAttribute == NSLayoutAttribute.Height)
{
constraint.Constant = newHeight;
}
}
Unfortunately, iOS8 adds a private height constraint to the inputAccessoryView, and this constraint is not public.
I recommend recreating the accessory view when its frame should change, and call reloadInputViews so that the new one is installed.
This is what I do, and it works as expected.
Yep, iOS8 adds a private height constraint to the inputAccessoryView.
Taking into account that recreating whole inputAccessoryView and replace old one is can be really expensive operation, you can just remove constraints before reload input views
[inputAccessoryView removeConstraints:[inputAccessoryView constraints]];
[textView reloadInputViews];
Just another workaround
To fix this I used inputAccessoryView.autoresizingMask = UIViewAutoresizingFlexibleHeight;
But of course this caused my textview to collapse.
So adding a constraint to the toolbar and updating it when I have to, or adding the constraint to the textview itself and update it worked for me.
frist, get inputAccessoryView and set nil
UIView *inputAccessoryView = yourTextView.inputAccessoryView;
yourTextView.inputAccessoryView = nil;
[yourTextView reloadInputViews];
then set frame and layout
inputAccessoryView.frame = XXX
[inputAccessoryView setNeedsLayout];
[inputAccessoryView layoutIfNeeded];
last set new inputAccessoryView again and reload
yourTextView.inputAccessoryView = inputAccessoryView;
[yourTextView reloadInputViews];
Here is the problem:
I have a bunch of views that I put in a UIScrollView. The size and position of those subviews are defined by constraints. This works perfectly, and scrolling works too. So far so good.
However, I want my scrollview to scroll all the way to the bottom when I show the viewcontroller on screen for the first time, and this is where trouble starts. In order to know where the bottom is I need to know the position and size of the lowest element in my subviews. Should be easy too (since I have the reference to that UIView somewhere): get the frame of the UIView and voila.
I want to scroll the scrollview to the bottom before it appears on screen (so basically, in viewWillAppear:), but the constraints only get evaluated after viewWillAppear and before viewDidAppear: is called.
Getting the UIView frame in viewWillAppear gives me a zero sized CGRect. Doing the same in viewDidAppear gives me the correct CGRect. But viewDidAppear is too late for me, since the scrollview is on screen already so you see the content moving up.
Does anyone have a good solution for this? I tried putting the code in viewDidLayoutSubviews but that doesn't work either.
The problem with viewWillAppear is that it is called before the layout happens. You have to adjust the scroll view's content offset after it is laid out - in viewDidLayoutSubviews method. in Here is my solution:
#property (nonatomic, assign) BOOL shouldScrollToBottom;
- (void)viewDidLoad
{
[super viewDidLoad];
_shouldScrollToBottom = YES;
}
- (void)viewDidLayoutSubviews
{
[super viewDidLayoutSubviews];
// Scroll table view to the last row
if (_shouldScrollToBottom)
{
_shouldScrollToBottom = NO;
[_scrollView setContentOffset:CGPointMake(0, CGFLOAT_MAX)];
}
}
I was running into this problem too! The view didn't scroll to the desired page before viewDidAppear(). It had multiple subviews to be layed out by viewDidLayoutSubviews(), so doing it once in that function, like Thomas suggested, didn't work for me either. However, the viewDidLayoutSubviews() approach works, if you use a little trick:
You need to attempt to scroll to the desired point every time viewDidLayoutSubviews() is called during the creation of the view. Then, after the view is displayed, you don't want this to be called anymore. So you add a control variable that is changed in viewDidAppear(), after the initial layout. Here's the full example:
var needsFirstScroll = true
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
if(needsFirstScroll) {
var frame = CGRect() // placeholder, do your frame calculation here
scrollView.scrollRectToVisible(frame, animated: false)
}
}
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
needsFirstScroll = false
}
This is what I did and it works for me (cell height computed by autolayout):
class MessagesTableViewController: UITableViewController
{
var shouldScrollToBottom = false
override func viewDidLoad()
{
super.viewDidLoad()
...
shouldScrollToBottom = true
}
override func viewDidLayoutSubviews()
{
super.viewDidLayoutSubviews()
if(shouldScrollToBottom == true)
{
shouldScrollToBottom = false
goToBottom()
}
}
private func goToBottom()
{
if(data.count == 0)
{
return
}
let indexPath = NSIndexPath(forRow: tableView.numberOfRowsInSection(0)-1, inSection: 0)
tableView.scrollToRowAtIndexPath(indexPath, atScrollPosition: .Bottom, animated: false)
}
}
The solution I finally came up with was to:
Store all subviews of the scrollview in 1 contentview and not directly as child of the scrollview
observe when the bounds of that contentview change
each time they change do a scrollRectToVisible to the bottom of the scrollview
disable the auto-scroll-to-bottom as soon as a scrollViewWillBeginDragging delegate call is detected so the auto-scrolling stops when the user starts moving the scrollview
I found a solution to this problem, this might be useful to future visitors. You need to load the tableView in viewWillAppear before trying to scroll.
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
[self.tableView reloadData];
[self.tableView scrollToRowAtIndexPath:[NSIndexPath indexPathForRow:[self.tableView.numberOfRowsInSection:0] inSection:0] atScrollPosition:UITableViewScrollPositionBottom animated:animated];
}