I'm adding content to the UIScrollView dynamically. The content size of the scroll view is increasing. How can I change the content size to fit the dynamically added content? See the code I'm using that is not working
extension UIScrollView {
func updateContentView() {
contentSize.height = subviews.sorted(by: { $0.frame.maxY < $1.frame.maxY }).last?.frame.maxY ?? contentSize.height
contentSize.height += 300
}
}
refer this question
I hope the above solves your problem but I'd prefer using a UITableView or a UICollectionView in place of this because everything is handled so smoothly in them. You just have to give the number of rows(return a variable which changes dynamically). That's it, your contentSize is adjusted internally.
But again if you have a different requirement please go with the reference link!
Related
I'm having this weird issue with UITableView that can't calculate it's content's height properly.
I have custom UITableView class that is embedded in another custom UITableView, I want it to auto-adjust it's height to fit content so I have already:
override var contentSize: CGSize {
didSet {
self.invalidateIntrinsicContentSize()
}
}
override var intrinsicContentSize: CGSize {
self.layoutIfNeeded()
return self.contentSize
}
And now when I use:
self.estimatedRowHeight = UITableView.automaticDimension // non-zero value like 40 isn't working either
self.rowHeight = UITableView.automaticDimension
the output is the frame that is not full height, when I turn "Scrolling enabled" in this TableView it's scrollable with full content (don't want that):
Now when I change
self.estimatedRowHeight = UITableView.automaticDimension
to:
self.estimatedRowHeight = 0
the output is exactly what I would want to have except the content text is cut...
Here's my CommentCell:
Console isn't showing any errors with autolayout in any case.
Do you maybe know what's going on? I have spent literally days trying to get those comments to work and that's the last thing I need.
If you need any more info please just tell me.
Edit:
If i change estimatedRowHeight to a large number for example 500 I get loads of empty space under cells:
So it looks like TableView can't fix the cell height to content. Maybe this will help someone.
Maybe it's about the textfield inside the CellView. Did you set it's Layout to wraps?
Also I would try to set it's intrinsic size value to 'placeholder' inside the Size Inspector.
I am tying to modify the height of a UITextView dynamically (up to a max height) while the user enters text. I am experiencing a very strange behavior when there are an even number of lines in the text view.
I am using autolayout and the text view has a height constraint. I respond to calls to the text view's delegate (textViewDidChange(_:)), where I calculate and adjust the height constraint based on the contentSize.
Here is the code:
func textViewDidChange(_ textView: UITextView) {
let newHeight = textView.contentSize.height
let newConstraintConst = max(MinTextViewHeight, min(MaxTextViewHeight, newHeight))
self.textViewHeightConstraint.constant = newConstraintConst
}
This works well, it resizes the frame up to MaxTextViewHeight and then the text view can scroll. However, when there are an even number of lines in the text view, the text view adds a kind of offset to the bottom of its NSTextContainer, causing the top line to be cut off:
However, when there are odd lines the NSTextContainer is no longer offset:
At first I thought it was somehow being controlled by the text view's textContainerInset but that is only used to pad the space inside the NSTextContainer, as setting it to .zero removes the space inside but does not affect the offset (and incidentally makes it even worse, as the top line almost completely disappears):
I have looked through the UITextView class reference and I don't see any property that would let me manipulate or even get the value of this offset.
As a workaround I am increasing the text container's top inset and removing the bottom inset:
textView.textContainerInset = UIEdgeInsetsMake(10, 0, 0, 0)
This works so far, but I arrived at a value of 10 by trial-and-error, and so far I've only tested it on a single device.
I am not interested in more hacky workarounds that require fragile, fixed values; I am trying to understand how this offset is being set and a proper way to fix it. I'm hoping that someone can provide some insight, thanks!
Just a speculation, but I think the problem is that the text view assumes that the height of itself does not change while calling textViewDidChange, so it scrolls when it thinks it has to, regardless of you changing its frame.
Not sure if you think my solution is too hacky, but this will stop it from scrolling when you don't want it. I simply pin the content offset to the top as long as the wanted content size is smaller than your max size.
Just add this:
func scrollViewDidScroll(scrollView: UIScrollView) {
if textView.contentSize.height <= MaxTextViewHeight && textView.contentOffset.y > 0.0 {
textView.contentOffset.y = 0.0;
}
}
Background
I am making a vertical label to use with traditional Mongolian script. Before I was just rotating a UILabel but there were some performance issues and other complications with this. Now I am working on making a label from scratch. However, I need the vertical label to tell auto layout when its height adjusts (based on string length).
What I have read
I read the Intrinsic Content Size and Views with Intrinsic Content Size documentation. These were more about how to use it, though, and not how to define it in a custom view.
Searching for "ios intrinsic content size for a custom view" only gives me
Proper usage of intrinsicContentSize and sizeThatFits: on UIView Subclass with autolayout
in Stack Overflow. This particular question didn't even need intrinsic content size because their view was just an assembly of standard views.
What I am trying
What I am trying is my answer below. I am adding this Q&A pair so that it won't take other people as long to find the answer as it took me with the search keywords that I used.
Setting the intrinsic content size of a custom view lets auto layout know how big that view would like to be. In order to set it, you need to override intrinsicContentSize.
override var intrinsicContentSize: CGSize {
return CGSize(width: x, height: y)
}
Then call
invalidateIntrinsicContentSize()
Whenever your custom view's intrinsic content size changes and the frame should be updated.
Notes
Swift 3 update: Easier Auto Layout: Coding Constraints in iOS 9
Just because you have the intrinsic content size set up in your custom view doesn't mean it will work as you expect. Read the documentation for how to use it, paying special attention to Content-Hugging and Compression-Resistance.
Thanks also to this Q&A for putting me on the right track: How can I add padding to the intrinsic content size of UILabel?
Thanks also to this article and the documentation for help with invalidateIntrinsicContentSize().
Example of a "view with intrinsic height" ...
#IBDesignable class HView: UIView {
#IBInspectable var height: CGFloat = 100.0
override var intrinsicContentSize: CGSize {
return CGSize(width: 99, height: height)
// if using in, say, a vertical stack view, the width is ignored
}
override func prepareForInterfaceBuilder() {
invalidateIntrinsicContentSize()
}
}
which you can set as an inspectable
Since it has an intrinsic height, it can (for example) be immediately inserted in a stack view in code:
stack?.insertArrangedSubview(HView(), at: 3)
In contrast, if it was a normal view with no intrinsic height, you'd have to add a height anchor or it would crash:
let v:UIView = HView()
v.heightAnchor.constraint(equalToConstant: 100).isActive = true
stack?.insertArrangedSubview(v, at: 3)
Note that in ...
the important special case of a stack view:
you set only ONE anchor (for vertical stack view, the height; for horizontal the width)
so, setting the intrinsic height works perfectly, since:
the intrinsic height indeed means that the height anchor specifically will be set automatically if needed.
Remembering that in all normal cases of a subview, many other anchors are needed.
This is a problem that has been bugging me for quite some time.
Assume a view that holds a tableView with X items. The goal is to make that view resize so that it is as high as the contents of the tableView.
An approach
Calculate the contents of the tableView in total ( e.g if there are 5 rows and each is 50 units high, its just a multiplication matter ). Then set the tableView constrained at a 0 0 0 0 into the view and set the view height to 250.
This works well for fixed height cell sizes. However!
a) How would the problem be approached for dynamic height cells though with complex constraints in a scenario where resizing happens automatically and the tableHeightForRow is set to UITableViewAutomaticDimension?
b) An idea could be using tableView.contentSize. However when would we retrieve that value safely in order to set the parent view frame accordingly? Is that even possible?
Thanks everyone
If you have a UITableView subclass, you can set up a property observer on the contentSize like this:
override var contentSize: CGSize {
didSet {
// make delegate call or use some other mechanism to communicate size change to parent
}
}
The most straightforward approach to this in my opinion is to use Autolayout. If you take this approach, you can use the contentSize to automatically invalidate the intrinsicContentSize which is what autolayout uses to dynamically size elements (as long as they don't have higher priority placement constraints restricting or explicitly setting their size).
Something like this:
override var contentSize: CGSize {
didSet {
self.invalidateIntrinsicContentSize()
}
}
override var intrinsicContentSize: CGSize {
return contentSize
}
Then, just add your table view to your parent view hierarchy with valid placement constraints and a content hugging/compression resistance of required.
I am having lots of trouble with this setup. So basically I am displaying some labels with variable height then a button and at the end of the view i need a WebView to display some HTML formatted text.
I resize the web view height constraint when the content is loaded as follows.
func webViewDidFinishLoad(webView: UIWebView) {
nContentViewHeight.constant = webView.scrollView.contentSize.height
}
When the view is first loaded, this works perfectly. The scrolling is good and all the web view content is visible.
But when I rotate the device I don't know how to properly resize the web view. I tried loading the content again in
override func didRotateFromInterfaceOrientation(fromInterfaceOrientation: UIInterfaceOrientation)
so that webViewDidFinishLoad would trigger again and resize the web view. But that doesn't work at all because the contentSize of the scrollview inside the web view doesn't change.
Not knowing why I attempted very ugly solution and that is this:
func fitWebAndScrollView(){
let newRect = CGRectMake(nContentWebView.frame.minX, nContentWebView.frame.minY, self.view.frame.width, 10)
let newWebView = UIWebView(frame: newRect)
newWebView.delegate = self
newWebView.tag = -12
newWebView.scrollView.scrollEnabled = false
self.view.addSubview(newWebView)
newWebView.loadHTMLString(contentHtml, baseURL: nil)
}
override func didRotateFromInterfaceOrientation(fromInterfaceOrientation: UIInterfaceOrientation) {
fitWebAndScrollView()
}
func webViewDidFinishLoad(webView: UIWebView) {
nContentViewHeight.constant = webView.scrollView.contentSize.height
if webView.tag == -12 {
webView.removeFromSuperview()
nContentViewHeight.constant *= 1.1 // longer the content is more of it is clipped
}
}
And this sort of works, but in some instance the bottom of the WebView content is clipped as if the inner scrollview content size is calculated incorrectly.
Has anybody dealt with this before? I always assumed that this sort of thing wasn't an extra special use case.
Thank you for your ideas.
Aright so I managed to solve it this way
func fitWebAndScrollView(){
if let strH = nContentWebView.stringByEvaluatingJavaScriptFromString("document.getElementById(\"cnt\").offsetHeight;"),
numH = NSNumberFormatter().numberFromString(strH){
nContentViewHeight.constant = CGFloat(numH)+20
}
}
override func didRotateFromInterfaceOrientation(fromInterfaceOrientation: UIInterfaceOrientation) {
fitWebAndScrollView()
}
func webViewDidFinishLoad(webView: UIWebView) {
fitWebAndScrollView()
}
The problem was actually with the HTML code I was using as a wrapper.
let htmlWrapperString = "<html><head>\n<style type=\"text/css\">body {font-family: \"%#\"; font-size: %#;-webkit-text-size-adjust: none;}</style></head><body><div id=\"cnt\">%#</div></body></html>"
So before I didn't have that wrapping div in the body and when I queried the height of body tag it always returned the whole view port size and not just the text height that was in body.
Now it works reliably.
First of all, if the code is really as shown, you are assigning the width of the content to the height constant. This would definitely cause the issue. (Apparently it is not as shown; please show actual code instead of typing in new "similar" code into the question…)
Second, it is not a very reliable way to detect the content height by only doing it in webViewDidFinishLoad. On some sites it may take a long time before this is actually called but the content may still be usable, and of course any action by the user in the browser may change it, and many websites append more content to the end of the page on the fly (e.g., as the user scrolls down).
Also, I hope you realize that scrollView.contentSize is the size of the content itself (not the visible part), and its height won't change on rotation unless the width is changed in a way that makes the content layout change.
Overall I think you may be trying to do something that UIWebView is simply not suited for. You should only autolayout the size of the webview itself, not have it inside an external UIScrollView (if I read the title correctly and that's what you are doing). Its inner scrollView will then handle the content scrolling for you automatically, instead of conflicting with your external scrollView. You can set yourself up as the delegate of the inner scrollview if you need to react to events from it, etc.
To resize the UIWebView itself on rotation, set up constraints to bind the distance from each of its edges to the surrounding views (or use the simpler autoresizingMask). There should be no need to do anything in didRotateFromInterfaceOrientation (and if you do need manual layout, do it in viewWillLayoutSubviews and/or viewDidLayoutSubviews).