I am working in Xcode 7, using Autolayout and targeting iOS 9.3. I have a Main View Controller that holds a Container View. The Container View holds a Child View Controller.
The Container View has a leading and trailing constraint of -20 so that it covers the Main View Controller fully in the horizontal.
When the Main View Controller loads for the first time, however, the content from the Child View Controller that is displayed inside the Container is slightly cut off on the left and the right (almost as if it does not recognize the constraint of -20 on the left and the right).
When I rotate the device to landscape and then back again to the original portrait orientation the Child View Controller suddenly scales correctly and is no longer cut off on the left and the right.
So it looks like some layout method is being called when rotating the device sideways and rotating it back again that does not get called when the view is first loaded. What method could this be? Is there a way that I can manually call this method to force an update on the layout/size when the child is first loaded so that it looks the same as after a rotation and backwards rotation?
First of all, you don't need to set the margin for -20. The 0 margin every side of container view is fairly enough to make the child view to spread out of the main container view. I have tried your idea but there is no problem. You can download the project from the github link below;
The link
I found a solution to the problem:
Instead of setting a leading and a trailing constraint of -20 on the Container View, I set a constraint on the Container View for the same width as the Main View and to center it horizontally in the container.
With these constraints it works on first load although I cannot quite explain why this would behave differently to the original constraints. I guess the lesson is that with Autolayout if one way of sizing your container behaves awkwardly under certain circumstances, try another set of constraints to achieve the same result.
Related
I am quite new in swift programming and I am developing an app which has multiple custom views, hope some one can help me here.
The issue is that I have a scrollView, inside I have a stackView with about 20 Views inside, every view has inferred constraints and every view has a fixed height, maybe not the best practice but most of the views show correctly (had to re-do about 3 times to get here), but one of my views (around the middle of the stack) is showing correctly in my story board, but somehow it's shrinking it's subviews when launching the app, not sure if I am missing something, I have even removed all the content of these subviews and left only the main views with their heights but still I have the same issue.
To be more detailed the section that fails is a view inside the vertical stackView, it contains a view (container) which has the same leading, trailing, top and bottom as the first one. This container view, contains 5 (sub)views which have the same height each (124), and have practically the same content: a label, a texfield and a custom slider (thought the slider was ruining everything because it's custom but after removing all from the design the error still occurs).
Here is an image of how it's shown in the story board:
views in story board
And here is how it's displayed in the emulator:
view in emulator
Does anybody now why can this be happening? I am not doing any layout stuff in the code only a couple of corner rounding in other views that are inside the stack view.
BTW, I also implemented this 5 slider views using a vertical stack and had the same issue, I switched and changed to simple views and separated by 10 each bottom with the next view top.
Thanks
Recently i was following a tutorial to create frameworks in Swift, Where they create reusable visual effect view just like we see in Xcode build success pop up. I was doing the UI step by step where they created a new xib file and dragged and dropped UIVisualEffectView into it.
In the above image we can see that the UIVisualEffectView doesn't contain any constraints. It only has auto resizing masks in size inspector(as expected).
But the following image from the tutorial suddenly contains all necessary constraints for it's root view.
I'm already aware that we CANNOT, by default set any constraints for the root view. But in the tutorial the author seems to have added constraints for the same. I'm just curious to know if it is possible to do that or am i missing any fundamental idea ?
EDIT:
Constraints for root view.
OK, found one way to do this...
Haven't done any testing, so I'm not sure if the constraints are really set correctly or will be used by auto-layout at run-time, but this will put them there.
Create a new "View" XIB - this is how it looks to start:
Add a Visual Effect view to this view, and give it width and height constraints of 230 / 230:
Now, drag that Visual Effects view *out of the plain view, onto an empty space:
You will see it maintains its constraints. Then delete the original view, and add the other elements:
As you can actually see on your screenshot the width/height constraints belong to the View (first subview of Visual Effect View).
Look at the green line:
I don't know what's going on your tutorial (and I have no intention of watching it), and I have no idea under what circumstances the screen shot was achieved. But I do know the rules for how a view controller's main view gets sized.
Any view controller's main view must expect to be resized as it is placed into the interface. The size in the storyboard is therefore meaningless. That is why you cannot give it a size with auto layout.
If a view in a xib or storyboard is to be used as the main view of a view controller, it is meaningless (and would be wrong) to set constraints on it, because it will be the task of the view controller's parent (or, in the case of the window's rootViewController, of the window) to set the size of the view when it places it into the hierarchy.
If a view controller wants to vote on the size of its view when it is placed into the view hierarchy (for example, as a popover), that is what the content size (preferred explicit size) is for. But even then, the parent is the one who controls what actually happens.
In my iOS app, my parent view has a child view which, in turn, has a number of UIButtons as children. Without constraints, touches on the buttons are recognized by the topmost view controller. However, when I add a constraint to center the child view (the one containing the UIButtons) horizontally within the parent, the parent stops recognizing the touches.
First of all, is this the correct/preferred way to do this (centering a group of views - e.g. buttons - by putting them in a View)? Should I be using a Container View, or stacked Stack Views, instead? (I tried a Container View, but (a) it generated its own controller, and (b) for some reason, I couldn't move the buttons into the container.)
Second, how do I get the view to recognize the touches while maintaining the constraint?
Apparently, the problem was, I needed to set a fixed width and height as well in order to get the layout set up correctly. Once I did that, it worked correctly.
I am using ios7 and I am enabled iAds with "self.canDisplayBannerAds"
The iAd basically reshapes the view when it shifts in or when it shifts out. However, When the banner shifts, my view Moves off screen!
In my story board, I put my view outside of the screen. And when the user presses a button, I set its frame property so that it exists inside of the screen. But when the iAd shifts in or out, the View travels back to its original place in the story board.
How can I prevent my view from sliding off the screen?
Update:
I tried simply adding a view programatically. and placed it in the same place as the one I made in Interface Builder. Initially they both move offscreen and on screen when commanded. however, once the iAd shifts in and out, the view I made in interface builder will slide out. The view I made programatically will stay put.
My best guess at this point was Auto layout or something to do with constraints. The IB view was sliding out rather than simply disappearing and It definitely was not using UIView's animation methods. Thus the only other thing that I could think of that could cause animations to happen are constrains. (eg rotating a view with view's that have constriaints will automatically resize in a smooth fashion.
so I took a look at the constraints of the view by calling the constraints method in an NSLog. It printed out a huge list of constraints. I did not add these explicitly, which means they were added automatically.
There may be a connection between these constraints. The question now is, why is the iAD banner triggering the view to basically spring back to its former place?
When the banner shifts in and out, it will layout the subviews. Views without any constraints are given automatic constraints. These constraints place it in the same location as it's place in the xib.
You can try changing the constraints.
I hate iOS scroll views with auto layout, they are driving me crazy!:-D
I have found a method which works perfectly on iOS 7 to use scroll views:
I put the scroll view directly in the main view, attaching the scroll view to the edges of the super view(top,bottom leading and trailing space equals to 0).
Then I put a UIView into the scroll view attached to the edges of the scroll view, (top,bottom leading and trailing space equals to 0).
Then I set the height constraint of the most internal view, I link it at my ViewController class, and I modify its value programmatically.
Or, if the view it's 'static' I put every component using the storyboard into the internal UIView, starting with the one at the Top attached to the top of the super view, the one under, attached with the constraint 'Vertical Spacing' referred to the one over him..and so on... Until the last, which is also attached to the bottom of the UIView..
Everything works fine in iOS 7, it's perfect, but iOS 6 is messing around with the constraint.
When I first launch the view everything is perfect, but it seems to recalculate the constraints even on the didappear(and in a bad way), in fact, if I leave my view while it's scrolled down, when I come back to it(let's say we are in a navigation controller) , is like it's everything 'moved up' and the components at the top are hidden.
Is there a way to make scroll views work in both iOS 6 and iOS 7, I'n thinking at two storyboards as the only solution, please tell me there is another way... :-)
thanks everyone, I post two images explaining my problem, taken from the top of the screen:
Well uncheck use AutoLayout in file inspector and try.