I am trying to add a UIView on top of the messagesCollectionView, but the collectionview seems to take up the whole screen making the UIView I want to add unable to be seen. I am looking at their documentation here: https://github.com/MessageKit/MessageKit/blob/master/Sources/Layout/MessagesCollectionViewFlowLayout.swift
My thoughts are to change something in the Layout delegate but I am unsure what and where to change... any thoughts on this would be appreciated!
Thanks!
If you want to have some sort of floating view above the messagesCollectionView, then you can just add it as a subview to the MessagesViewControler's view, just make sure to do it after you've called super.viewDidLoad() because that's where MessageKit adds the collectionView as a subview so if you add it before then, then your view will be behind the collectionView and won't appear. To prevent the cells overlapping with your view, you can use messagesCollectionView.contentInset property to add padding to either the top or bottom if your view is floating there, so that the user can still scroll to all of the messages. Something like this:
override func viewDidLoad() {
super.viewDidLoad()
let subview = UIView()
view.addSubview(subview)
// Either add constraints or set the frame manually
// ...
// Set the contentInset if you want to prevent the messages from overlapping your view
messagesCollectionView.contentInset.top = 10 // For example, if your view was stickied to the top and was height 10px
}
Another route you could go is to have a parent view controller where you add the MessagesViewController as a child VC to the parent, and then size and layout the messagesCollectionView how you want. You can see an example of this in the MessageKit example app, in the MessageContainerController class: https://github.com/MessageKit/MessageKit/blob/master/Example/Sources/View%20Controllers/MessageContainerController.swift
I have a ViewController with a ScrollView inside (pinned to edges, 4 constraints). Everything fine.
I then add a TableViewController as a ChildViewController to the ScrollView. The TableViewController is hardcoded to have 3 rows. The TableViewController's view is pinned to the full ScrollView.
#IBOutlet weak var SV: UIScrollView!
override func viewDidLoad()
{
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let TVC = storyboard.instantiateViewController(withIdentifier: "TVC") as! TVC
addChildViewController(TVC)
SV.addSubview(TVC.view)
TVC.didMove(toParentViewController: self)
TVC.view.translatesAutoresizingMaskIntoConstraints = false
TVC.view.topAnchor.constraint(equalTo: SV.topAnchor).isActive = true
TVC.view.leadingAnchor.constraint(equalTo: SV.leadingAnchor, constant: 100).isActive = true
TVC.view.trailingAnchor.constraint(equalTo: SV.trailingAnchor, constant: -100).isActive = true
TVC.view.bottomAnchor.constraint(equalTo: SV.bottomAnchor).isActive = true
}
If I open debugger, I see that the ScrollView layout is ambiguous and that override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell never gets called for the table view controller (why ?).
Instead, if I simply add a label within the storyboard or any other view, inside the scrollview, and add 4 constraints to it, then the TableView will be shown and override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell is called as expected.
What's up with this ? ScrollView shouldn't be ambiguous, because the TableView should calculate it's own intrinsic content size ? What's wrong with the tableview that it never populates itself if it's alone inside the ScrollView ?
I'm adding the whole sampleproject. If you run it, the result is expected, the tableview is shown. If you go to storyboard and remove the label from the ScrollView, then the TableView won't be populated at all.
I don't know how I can directly add the sampleproject here, so I uploaded it. Just run it, then remove the only label from storyboard and re-run it, no more table view.
https://wetransfer.com/downloads/e0a75a995992cdc2be9120224515549920181003074547/1083bc9a3cb34fe9b1ab8e513b1520f020181003074547/e68826
PS: ignore other things, like child view controlers in there. My only question is why the tableview is shown when the label exists inside the same ScrollView and not shown when the label is removed.
First of all, the constraints applied to the views inside a ScrollView are a little bit, let's say, special. They are not linked to the ScrollView's frame, they are sort of linked to the ScrollView's "contentSize". Normally, if you would have a View inside another view, and the inside view is pinned in all directions to the superView, it will either stretch to match the parent size (if the parent constraints are well defined to a different parent), or the parent will "wrap" the child size, if the parent constraints are not defined relative to another parent.
Now the ScrollView behaves a little bit different in this case, the ScrollView size will never "wrap" the child. The child constraints are added just to tell the ScrollView, what's the scroll area (contentSize).
Moreover, in your case the UITableView, you can think of it like a "special" ScrollView, can't provide enough information for the ScrollView in order to compute the scrollableContent. If you pin the tableView in all directions, it will just tell the TableView, "align with the parent in all directions" but the scroll view will not know "how much can I scroll".
So because of the above problem, you usually add a UIView inside the ScrollView to act as a "container" and depending on the scrollDirection, you set the view width/height to be equal to the ScrollView or to the parent of the scrollView (again depending on the use case). Then all the content that you want to be inside the scrollView it's added inside the UIView. Also the content is pinned in such way, that it won't allow "compression" to force the parent view (aka container) to stretch to "wrap" the whole content, in this way, the scroll will know how much is the scroll area.
ScrollView shouldn't be ambiguous, because the TableView should calculate it's own intrinsic content size ?
This one is wrong, the intrinsic content size, defines the minimum size that the view needs in order to be drawn. Now think about this, how much space does a tableView needs in order to be drawn, if no other special implementation is added, the answer is 0. The tableView can have a width/height of 0, there's no constraints to prevent this.
Now to wrap it up, your implementation is a little bit wrong, to fix it, I suggest to have a close look over one of the many tutorials that shows how to implement a UIScrollView with auto-layout.
You'll see that most of the implementations will:
add a UIView inside the UIScrollView (aka "containerView)
then the view will be pinned in all directions to the UIScrollView
then either the width or the height of the container will be set to be equal to the scrollView or the parent of scroll view
then content will be added inside the "containerView"
then constraints will be applied to the content in such way that the container will have to wrap around the content.
I'm developing a little app in Swift 2.0. I have a View with the following hierarchy:
Now, the elements placed in this view can't be displayed entirely in it, so I would like to use a ScrollView in order to be able to scroll all the content.
How I can embed all the content of my Viewto a new ScrollView? Can I do this programmatically by code?
UPDATE: There's an easier way to do this which I didn't know when I posted this answer
1) Go to the viewcontroller on the storyboard and click on something in it and press Command + A. This will select all the elements in the view.
2) Go to Editor -> Embed In -> Scroll View. This will embed all the labels, views, etc into a scrollView.
3) Select the scrollview that you just embedded. Press Control and drag it to the respective class file of the viewcontroller and create an outlet scrollView.
4) Add this to your viewDidLoad()
scrollView.contentSize = CGSizeMake(self.view.frame.width, self.view.frame.height+100)
Make sure the height for the contentSize is more than the size of your view.
ADDING SCROLLVIEW MANUALLY
1) Drag and drop a scrollview from the Object Library onto your viewcontroller in the storyboard and create an outlet to your program as 'scrollView'.
2) Click on your viewcontroller and go to the size inspector and note down the width and height.
3) Click on your scrollview and set the width and height the same as the viewcontroller. and set the X and Y values to 0
4) Click on the scrollView and drag it a little bit to the side
5) Press Command+A to select all the elements including scrollView. Press Command and click on the scrollView to deselect the ScrollView
6)You will have all the elements except the scrollView selected now. Now click and drag them into the scrollView.
7) Now click on the scrollView and set the X and Y values to 0 from the Size Inspector.
8) Add this to your viewDidLoad()
scrollView.contentSize = CGSizeMake(self.view.frame.width, self.view.frame.height+100)
Make sure the height for the contentSize is more than the size of your view.
That should create a scrollView for your view. Some of the elements might be in a slightly different position. You can easily fix them by moving them on your storyBoard.
It can be done even simpeler than ebby94's answer.
1) Go to the viewcontroller on the storyboard and click on something in it and press Command + A. This will select all the elements in the view.
2) Go to Editor -> Embed In -> Scroll View. This will embed all the labels, views, etc into a scrollView.
3) Set the constraints of the Scroll View to the View's edges.
And you're good to go! No need for an outlet.
If you are using Snapkit or creating programmatically.
class ScrollViewController: UIViewController {
lazy var contentViewSize = CGSize(width: self.view.frame.width, height: self.view.frame.height + 320) //Step One
lazy var scrollView : UIScrollView = {
let view = UIScrollView(frame : .zero)
view.frame = self.view.bounds
view.contentInsetAdjustmentBehavior = .never
view.contentSize = contentViewSize
view.backgroundColor = .white
return view
}()
lazy var containerView : UIView = {
let view = UIView()
view.frame.size = contentViewSize
view.backgroundColor = .white
return view
}()
override func viewDidLoad() {
self.view.addSubview(scrollView)
self.scrollView.addSubview(containerView)
//Now Set Add your Constraints in the container View.
}
}
Above accepted answer explanation is enough to achieve the scroll view but I would prefer to create my complete application programatically and I don't use storyboards in my project. This code is for the folks who don't prefer to use storyboards.
Explanation
Step One: Determine your content Size. Here I am taking Exact width and adding 320 more to the height of the screen.
Step Two: Create a scroll view and add desire behaviour of the scroll view. Now, the contentSize of the scroll view should be same as the contentSize you've created above at step one.
By Following Step one and Step Two. You Will be able to set a scroll view on the top of the view. But If you want to add a stretching behaviour then You should follow Step Three
Step Three: Create a container view of the same size of the contentView which you've calculated in step one and set it to the frame of the containerView. By doing this you'll be able to achieve stretching header and footer behaviour in your screen.
Please read make sure to add constraints in the same order as it is set.
Answer Edits are welcome.
I had the same issue. I needed to add scrollview to the existing view.But my main container view has a lots of view inside it. And they were connected to each other. So i was afraid. Finally i did it. the process given below.
Duplicate your View (root View). For this first select the root view then press Command + D
Now delete all the child view view inside the root view
Now add a scroll view to the root view and set constraint to 0,0,0,0
Now add the duplicate(That you duplicated) view to the scroll view and set constraints to 0,0,0,,0 also set the height that you want.
Set width of the duplicate view by equal width with the root view.
Now select the viewController, go the size inspector, select free form size. Then set the height that you entered with duplicate view.
You have almost done. Now you have to connect the child view with outlet or action that you gave in the viewController class.
Thats all.
Selecting all elements and embedding scroll view (editor->embed in->scrollView) works fine.
Adding constraint is much more easy by selecting the constraint warning (Add Missing Constraints).
It's simple. Command A and Command X to specific view controller in StoryBoard. After that take scroll view. On scroll view, just take one view with view controller view height and width equal to scroll View width. Again do Command V and rearrange the constraints. Your problem will be solved.
I have a UIScrollView which contains many UIImageViews, UILabels, etc... the labels are much longer that the UIScrollView, but when I run the app, I cannot click and scroll down...
Why might this be?
Thanks
It's always good to show a complete working code snippet:
// in viewDidLoad (if using Autolayout check note below):
UIScrollView *myScrollView;
UIView *contentView;
// scrollview won't scroll unless content size explicitly set
[myScrollView addSubview:contentView];//if the contentView is not already inside your scrollview in your xib/StoryBoard doc
myScrollView.contentSize = contentView.frame.size; //sets ScrollView content size
Swift 4.0
let myScrollView
let contentView
// scrollview won't scroll unless content size explicitly set
myScrollView.addSubview(contentView)//if the contentView is not already inside your scrollview in your xib/StoryBoard doc
myScrollView.contentSize = contentView.frame.size //sets ScrollView content size
I have not found a way to set contentSize in IB (as of Xcode 5.0).
Note:
If you are using Autolayout the best place to put this code is inside the -(void)viewDidLayoutSubviews method .
If you cannot scroll the view even after you set contentSize correctly,
make sure you uncheck "Use AutoLayout" in Interface Builder -> File Inspector.
You need to set the contentSize property of the scroll view in order for it to scroll properly.
If you're using autolayout, you need to set contentSize in viewDidLayoutSubviews in order for it to be applied after the autolayout completes.
The code could look like this:
-(void)viewDidLayoutSubviews
{
// The scrollview needs to know the content size for it to work correctly
self.scrollView.contentSize = CGSizeMake(
self.scrollContent.frame.size.width,
self.scrollContent.frame.size.height + 300
);
}
The answer above is correct - to make scrolling happen, it's necessary to set the content size.
If you're using interface builder a neat way to do this is with user defined runtime attributes. Eg:
Try to resize the content size to huge numbers. I couldn't understand why my scroll view doesn't scroll even when its content size seems to be bigger than control size. I discovered that if the content size is smaller than needed, it doesn't work also.
self.scrollView.contentSize = CGSizeMake(2000, 2000);
Instead of 2000 you can put your own big numbers. And if it works, it means that your content size is not big enough when you resize.
The delegate is not necessary for scroll view to work.
Make sure you have the contentSize property of the scroll view set to the correct size (ie, one large enough to encompass all your content.)
Uncheck 'Use Autolayout' did the trick for me.
Environment:
xCode 5.0.2
Storyboards
ios7
In my case I had to set delaysContentTouches to true because the objects inside the scrollView were all capturing the touch events and handling themselves rather than letting the scrollView itself handle it.
Set contentSize property of UIScrollview in ViewDidLayoutSubviews method. Something like this
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
scrollView.contentSize = CGSizeMake(view.frame.size.width, view.frame.size.height)
}
if you are getting a message (IOS8 / swift) that viewDidLayoutSubviews does not exist, use the following instead
override func viewDidAppear(animated: Bool)
This fixed it for me
The idea of why scroll view is not scrolling because you set the content size for scrolling less than the size of the scroll view, which is wrong.
You should set the content size bigger than the size of your scroll view to navigate through it while scrolling.
The same idea with zooming, you set the min and max value for zooming which will applied through zooming action.
welcome :)
One small addition, all above are the actual reasons why your scroll view might not be scrolling but sometimes mindlessly this could be the reason specially when scrollview is added through code and not IB, you might have added your subviews to the parent view and not to the scrollview this causes the subview to not scroll
and do keep the content size set and bigger than parent view frame (duhh!!)
I made it working at my first try. With auto layout and everything, no additional code. Then a collection view went banana, crashing at run time, I couldn't find what was wrong, so I deleted and recreated it (I am using Xcode 10 Beta 4. It felt like a bug) and then the scrolling was gone. The Collection view worked again, though!
Many hours later.. this is what fixed it for me. I had the following layout:
UIView
Safe Area
Scroll view
Content view
It's all in the constraints. Safe Area is automatically defined by the system. In the worst case remove all constraints for scroll and content views and do not have IB resetting/creating them for you. Make them manually, it works.
For Scroll view I did: Align Trailing/Top to Safe Area. Equal Width/Height to Safe area.
For Content view I did: Align Trailing/Leading/Top/Bottom to Superview (the scroll view)
basically the concept is to have Content view fitting Scrollview, which is fitting Safe Area.
But as such it didn't work. Content view missed the height. I tried all I could and the only one doing the trick has been a Content view height created control-dragging Content view.. to itself. That defined a fixed height, which value has been computed from the Size of the the view controller (defined as freeform, longer than the real display, to containing all my subviews) and finally it worked again!
Add the UIScrollViewDelegate and adding the following code to the viewDidAppear method fixed it for me.
#interface testScrollViewController () <UIScrollViewDelegate>
-(void)viewDidAppear:(BOOL)animated {
self.scrollView.delegate = self;
self.scrollView.scrollEnabled = YES;
self.scrollView.contentSize = CGSizeMake(375, 800);
}
My issue was resolved by:
setting the contentSize on the scrollView to a large height
BUT also I had to fix top and/or bottom constraints on views within the scrollView, which meant the scroll indicators showed on screen but the content did not scroll
Once I removed top and/or bottom constraints bound to the safe area and/or superview, the views inside the scrollView could scroll again and didn't stay fixed to the top of bottom of the screen!
Hope this stops someone else from hours of pain with this particular issue.
yet another fun case:
scrollview.superview.userInteractionEnabled must be true
I wasted 2+hrs chasing this just to figure out the parent
is UIImageView which, naturally, has userInteractionEnabled == false
Something that wasn't mentioned before!
Make sure your outlet was correctly connected to the scrollView! It should have a filled circle, but even if you have filled circle, scrollView may not been connected - so double check! Hover over the circle and see if the actual scrollview gets highlighted! (This was a case for me)
//Connect below well to the scrollView in the storyBoard
#property (weak, nonatomic) IBOutlet UIScrollView *scrollView;
Alot of the time the code is correct if you have followed a tutorial but what many beginners do not know is that the scrollView is NOT going to scroll normally through the simulator. It is suppose to scroll only when you press down on the mousepad and simultaneously scroll. Many Experienced XCode/Swift/Obj-C users are so use to doing this and so they do not know how it could possibly be overlooked by beginners. Ciao :-)
#IBOutlet weak var scrollView: UIScrollView!
override func viewDidLoad() {
super.viewDidLoad()
view.addSubview(scrollView)
// Do any additional setup after the view
}
override func viewWillLayoutSubviews(){
super.viewWillLayoutSubviews()
scrollView.contentSize = CGSize(width: 375, height: 800)
}
This code will work perfectly fine as long as you do what I said up above
If none of the other solutions work for you, double check that your scroll view actually is a UIScrollView in Interface Builder.
At some point in the last few days, my UIScrollView spontaneously changed type to a UIView, even though its class said UIScrollView in the inspector. I'm using Xcode 5.1 (5B130a).
You can either create a new scroll view and copy the measurements, settings and constraints from the old view, or you can manually change your view to a UIScrollView in the xib file. I did a compare and found the following differences:
Original:
<scrollView clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="scaleToFill" directionalLockEnabled="YES" bounces="NO" pagingEnabled="YES" showsHorizontalScrollIndicator="NO" showsVerticalScrollIndicator="NO" translatesAutoresizingMaskIntoConstraints="NO" id="Wsk-WB-LMH">
...
</scrollView>
After type spontaneously changed:
<view clearsContextBeforeDrawing="NO" contentMode="scaleToFill" translatesAutoresizingMaskIntoConstraints="NO" customClass="UIScrollView" id="qRn-TP-cXd">
...
</view>
So I replaced the <view> line with my original <scrollView> line.
I also replaced the view's close tag </view> with </scrollView>.
Be sure to keep the id the same as the current view, in this case: id="qRn-TP-cXd".
I also had to flush the xib from Xcode's cache by deleting the app's derived data:
Xcode->Window->Organizer->Projects, choose your project, on the Derived Data line, click Delete...
Or if using a device:
Xcode->Window->Organizer->Device, choose your device->Applications, choose your app, click (-)
Now clean the project, and remove the app from the simulator/device:
Xcode->Product->Clean
iOS Simulator/device->press and hold the app->click the (X) to remove it
You should then be able to build and run your app and have scrolling functionality again.
P.S. I didn't have to set the scroll view's content size in viewDidLayoutSubviews or turn off auto layout, but YMMV.
If your scrollView is a subview of a containerView of some type, then make sure that your scrollView is within the frame or bounds of the containerView. I had containerView.clipsToBounds = NO which still allowed me see the scrollView, but because scrollView wasn't within the bounds of containerView it wouldn't detect touch events.
For example:
containerView.frame = CGRectMake(0, 0, 200, 200);
scrollView.frame = CGRectMake(0, 200, 200, 200);
[containerView addSubview:scrollView];
scrollView.userInteractionEnabled = YES;
You will be able to see the scrollView but it won't receive user interactions.
adding the following code in viewDidLayoutSubviews worked for me with Autolayout. After trying all the answers:
- (void)viewDidLayoutSubviews
{
self.activationScrollView.contentSize = CGSizeMake(IPHONE_SCREEN_WIDTH, 620);
}
//set the height of content size as required
The straightforward programmatically way
To wrap it up
Create a UIScrollView
private lazy var scrollView: UIScrollView = {
let scrollView = UIScrollView()
scrollView.translatesAutoresizingMaskIntoConstraints = false
return scrollView
}()
Use a Single Child View to Hold All of Your Content Subviews
private lazy var contentView: UIView = {
let view = UIView()
view.translatesAutoresizingMaskIntoConstraints = false
return view
}()
Add your views
contentView.addSubview(firstSubView)
contentView.addSubview(lastSubView)
scrollView.addSubview(contentView)
view.addSubview(scrollView)
Usually, you only want your content to scroll in one direction. In most cases to scroll vertically. Therefore set the width of the content view to be the width of the scroll view.
NSLayoutConstraint.activate([
contentView.widthAnchor.constraint(equalTo: scrollView.widthAnchor)
Attach four constraints (top, bottom, left, right) from our single content view to the scroll view.
contentView.topAnchor.constraint(equalTo: scrollView.topAnchor),
contentView.leadingAnchor.constraint(equalTo: scrollView.leadingAnchor),
contentView.trailingAnchor.constraint(equalTo: scrollView.trailingAnchor),
contentView.bottomAnchor.constraint(equalTo: scrollView.bottomAnchor),
Make sure you have constraints attached to all four sides of the content view so that it will expand to the size of your content.
// After Adding your subviews to the contentView make sure you've those two constraints set:
firstSubView.topAnchor.constraint(equalTo: contentView.topAnchor),
.
.
.
lastSubView.bottomAnchor.constraint(equalTo: contentView.bottomAnchor),
])
Reference: Using UIScrollView with Auto Layout in iOS
After failing with the provided answers in this thread, I stumbled upon this article with the solution.
There are two things not intuitive about setting up the scrollview with autolayout:
The constraints you set up as margin between the contentview and scrollview do not influence the size of the contentview. They really are margins. And to make it work, the contentview should have a fixed size.
The trick to the fixed size is that you can set the width of the contentview equal to that of the scrollview's parent. Just select both views in the tree on the left and add the equal widths constraint.
This is the gist of that article. For a complete explanation, including illustrations, check it out.
I found that with this AutoLayout issue... if I just make the ViewController use UIView instead of UIScrollView for the class... then just add a UIScrollView myself... that it works.
I had the same issue in IB.
After setting the leading, trailing, top and bottom of the scrollView to its superView. I made the following changes to make the containerView scrollable, which worked.
To make the scrollView only scroll on horizontal direction make the constraint with scrollView's centerY = ContainerView's centerY
and to make it vertically scrollable make the scrollView's centerX = ContainerView's centerX
You don’t have to set the content size of the scroll view.
Technical Note TN2154
In case someone made the same mistake like me, I'd like to share my case.
In my case, I mistakenly add a constraint to one of the subviews of scrollview which makes the subview's space to the topLayoutGuide fixed, thus it's location can't be changed, so the scrollview can't be scrolled.