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.
Related
I have created a UIView that consists of 3 UILabels and 1 UIImageView as below -
The UILabels have lines set to 0 so that the height of the UILabels change dynamically
I have added constraints such that the height of the image depends on the height of the UILabels as shown below -
I have set width of the UIImageView to a constant of 100.
I would like to set a constraint on UIImageView such that the height of the UIImageView is equal to the height of the whole view.
I tried adding a "Equal Heights" constraint on the UIImageView and the whole view. I observed that the height of the whole view depends on the height of the UIImageView and not that the height of the UIImageView depends on the whole view as I want it to be.
Can anyone point out how I can add a constraint to the UIImageView such that its height is equal to its superview but the height of the superview is not dependent on the UIImageView?
Edit -
The below image shows the problem that I am facing. When an image is set to the UIImageView, the height of the view changes.
I want the height of the UIImageView to be equal to the height of the view, but I do not want the height of the view to be dependent on height of the UIImageView
Looks like you need to reduce the vertical content compression resistance on the image view.
Set it to something very low like 100 and try again.
I believe you haven't add the height constraint to the superview. Setup height constraint for the superview and then add a "Equal Heights" constraint on the UIImageView and the whole view.
In fact default compression resistance of your UIImageView is 750, while content hugging of root UIView is 250. This means AutoLayout engine layouts everything correctly. You can change vertical compression resistance to value lower then 250 (UILayoutPriority.defaultLow - 1) to achieve desired layout.
This is my setup:
I do not know what I am doing wrong. The image view is bigger than the size of the view and of the scroll view. The constrains are set al followed:
Scroll view: equal heights to View * 0,5, equal width to View, center Y and X to View.
View (inside Scroll view): pinned all zero's inside Scroll view, equal heights and width. I also tried instead of equal heights and widths to center X and Y inside Scroll view, but it won't scroll.
How can I let the Scroll view scroll? Thank you.
Add a leading, trailing and top constraint and equal height of UIScrollView to superview with 0.5 multiplier. Now to your contentView (the UIScrollView subview), add a leading, trailing , top and bottom constraint. Also add equal height and width to UIScrollView. Set the height to a priority of 250. Add constraints for UIImageView inside this contentView.
Since the contentView will have a fixed height of low priority equal to the UIScrollView height. This fixed height constraint will break once the UIImageView total height(based on the constraints you add) will get larger than the UIScrollView height and the content will become scrollable. So at the very least you will always have a view half the screen size and become scrollable once the content becomes too large vertically.
You need to give contentSize to scrollview.
ScrollView.contentSize = CGSize(width: 1000, height: 500)
Which constrains have you given to imageview?
set constraint of imageview:
Trailing ,leading,top,bottom - 0 and also give height constraint.
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
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);
I have 2 views(say topView and bottomView) in my UIViewController with topView at top. Both views grow with aspect ratio constraint. topView and bottomView has 0 vertical space between them. I want to hide bottomView in a particular case. But problem is that I don't have height constraint available for it. I only have Vertical Space constraint between topView and bottomView. So I decided to move bottomView under topView. I tried to do following in view controller's viewDidLayoutSubViews
self.verticalSpaceConstraint.constant = -1*[bottomView intrinsicContentSize].height;
and
self.verticalSpaceConstraint.constant = -1*[bottomView bounds].size.height;
The intrinsicSize always returns (1,1) and bounds always returns (0,0,320,568). How can I achieve this it?
You can add height constraint (with constant value 0) and aspect ratio constraint both at a same time to the view, but these constrains should have different priorities and non of these with priority 1000 (required). Then to hide view just set programmatically priority of aspect ratio constraint lower then height constraint or vice versa to show it. Hope this helps