Auto layout with UIScrollView using .xib - ios

I have enabled auto layout in my .xib but unfortunately, scroll view does not scroll anymore.
Constraints on my view:
Constraints on my scrollView:
Constraints on my contentView:
What I am missing here. Thanks for your help.

Try to set contentSize like
sview.contentSize = CGSizeMake(ScreenWidth, 1000);

The contentsize of the scrollView should be determined by the contentView's needed height automatically. Make sure the subviews of contentView have all vertical constraints so the contentView will adapt in height.
In your case you've set contentView.height == view.height. It should work if you remove this constraint and make sure contentView does expand(height) according to it's subviews.

Add one more constraint of Contentview height >= Current height
This will do the trick

You can refer this. It is a nice tutorial for Autolayout with ScrollView.

Related

Unexpected width of view

I have a UIImageView object which has constraints "equal width" and "equal height" to "superview" (ViewController's main view).
When I debugging, imageView's width and height isn't equal with ViewController's width and height. Am I missing something ?
The constraints are applied somewhere between after viewDidAppear and before viewDidLayoutSubviews. It is really frustrating as you don't have access to the correct size until the view is already visible to the user.
what you can do to cover the hole view is to add to the imageView trailing, leading, top and bottom constraints = 0 and remove the height and width constrains.
hope it helps.

UIScrollView does not Scroll completely

I have a ViewController. In it I put ScrollView with the View(contentView). Later I drag from contentView to View and set Equal Height. Now it scrolls, but not fully.
As you see there are it has continue below the textView, but it
doesn't scrolls. How can I fix it?
UIScrollView is able to automatically calculate it's content height and width, but you need to help it with this.
To do so you need to:
Bound contentView (in your case) to all sides of superview (which is Scroll View).
Let contentView to calculate it's sizes. Here is a small mistake in your approach. You've set height of the contentView equal to View's height. So basically Scroll View's contentSize.height is the same as View's height. Which is not really what you want with dynamic content.
Usually you want to set width of the contentView equal to View's width and do not set contentView's height. Instead you want to bind subviews of contentView to their superview in such a way that their superview (contentView) will calculate it's height automatically.
In your case I would bind:
pizza.jpg to left-top-right of superview (height of pizza.jpg will be set from intrinsic image size);
SAMPLE TITLE label - left-right to superview; top to pizza.jpg image;
Text View - left-bottom-right to superview; top to SAMPLE TITLE label; set a fixed height.
In this case contentView will define needed height by itself. Scroll View will set it's contentSize accordingly.
And your screen will be able to scroll vertically (it should be) ;)
You need to set the contentsize of the scrollview. Use the below code to do that:
func viewDidLayoutSubviews()
{
super.viewDidLayoutSubviews()
self.scrollView.contentSize = CGSizeMake(self.view.frame.size.width, self.contentView.frame.size.height);
}
To use Autolayout with UIScrollView is tricky.
In your code you have to update height constraint for your contentView by calculating height of subviews of contentView and that will automatically update the contentSize for your ScrollView and you can scroll through all subviews.
For more info to use Autolayout+UIScrollView your can read this.
According to this link (thanks to this Matt's answer first), UIScrollView acts differently with AutoLayout than the other views.
Subviews of a scrollView set their constraints from the contentView of the scrollView and not the scrollview directly. This allows the content to scroll.
So :
Add a UIView to your scrollView, this will represent the contentView of your scrollView. Add constraints to top, bottom, trailing, leading from the view to its superView
Interface Builder complains. Here you see the different between a basic view and a scrollView. The reason is a contentView has to be fill to know its size. So add a equal width from the contentView to the scrollView
The contentView knows now its width but not its height. So add your labels and your UIImage as subviews of the contentView. Add constraints from bottom to the top. Don't miss to add a height constraint to the UIImageView.
It should look like this :
Hope this helps
Read this (from Matt once again) for further informations

How to make uiscrollview only vertical scrolling for ios?

I'm trying to make layout inside scrollview using this one tutorial link
And get the following result link
It will be appreciated for any advices or tutorial links. It needs only vertical scrolling
I am sure there must be other ways to do this but a quick fix is :
1.) Create a width constraint on ContentView in Storyborad.
2.) IBOutlet that widthContraint and set its value to the view frame width in viewDidLoad.
Suppose the name of the constraint outlet is contentViewWidthContraint.
contentViewWidthContraint.constant = self.view.bounds.size.width;
Another alternative to do so from Storyboard, is to fix the Contentview width to the view's width from the storyboard or to the Scrollview, if Scrollview already has a Equal width contraint with superview . Add the "Equal Width" contraint from Contentview to either self.view or to Scrollview (if scrollview, already has the width contraint)
Have you set up the "ContentView" width to match with the scroll view width? I had the same problem and I fixed with "Equal Widths".
"Equal Widths" will tell to your "ContentView" to use the same width of the "Scroll View", which should be fitting the screen if you have set up the constrain properly.
You can do this easily on the storyboard.
Drag and drop, with right click (important!!!), from "ContentView" to "ScrollView"
Release the click, you will be prompted with a menu, select "Equal Widths".
This should fix your problem using the scrollview with AutoLayout from Storyboard editor.
You can find a full tutorial how to use ScrollView with Autolayout and Storyboard here.
I hope this is useful for you :)
In the Storyboard set the width of the elements contained in your UIScrollView equal to the width of this UIScrollView (by selecting all elements and the UIScrollView holding in the panel on the left of your Storyboard and then setting the 'Equal Widths' constraint under 'Pin' on the bottom of your Storyboard). Just pinning the right sides of the elements to that of the UIScrollView won't work as it will adjust the size of its "display view" to the width of the largest element and if this is smaller than the width of the UIScrollView all elements will just appear aligned to its left side.
There is also another possibility that offers a very good result.
You can mark a checkbox:
O programmatically:
scrollView.alwaysBounceVertical = true
Try to set it's width to 0 & height equal to content size like this:
self.scrollView.contentSize = CGSizeMake(0, self.scrollView.contentSize.height);
This will work as you want. Try it & tell if still facing any issue.
For disabling the horizontal scroll, you can set the content size in the -(void)scrollViewDidScroll method.
[self.scrollView setContentOffset: CGPointMake(0, self.scrollView.contentOffset.y)];
self.scrollView.directionalLockEnabled = YES;
This is because scroll view have no idea where your content should end.
But when at least one item inside your scroll view has its "trailing space" constraint attached to a view outside the scroll view (usually a view the scroll view is sitting in or some other view of a higher level, which "knows" its width) - the scroll view will automatically get an idea about your wanted width and won't scroll horizontally (unless that trailing constraint implies having your content outside the screen).
Better if all items inside scroll view have their "trailing space" constraints connected either to each other or to a view outside the scroll view. But not the scroll view itself.
No additional code or extra constraints needed for this to work.
Too set UIScrollView constraints as like below code so it will occupied whole screen.Not exceed the screen size.
Leading Space = 0 from mainView
Top Space = 0 from mainView
Bottom Space = 0 from mainView
Trailing Space = 0 from mainView
You need to set the width of UIScrollView equal to or less than the width of your Parent View. Two ways to do it:
1) You can do this in Storyboard via layout constraints
2) You can do this programatically:
self.scrollView.contentSize = CGSizeMake(self.view.frame.size.width, self.scrollView.contentSize.height);

ContentView in UITableView cell has offset

Doing it in a xib:
For some reason the contentView has an offset of 8px, although it has no constraints to it's parnet view (and I can't set one myself)
How can I set it to 0?
Constrain to margins. Set this property no. Its a new property. On constraint window.

UIScrollView not scrolling

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.

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