I am new to autolayout.
I have got a view hierarchy working fine with autolayout.
I got a container view displaying a menu. I am animating this view using Dynamics to make a pop effect: the view grows from a tiny size to its target size.
The effect is great. The problem is, since the view needs to be shrink to a tiny tiny size (like 5x5 at the beginning), all the first part of the animation cannot resolve my subviews constraints (like leading AND trailing space cannot be both 10 because the view itself is 10).
I don't care if at this minimum scale the layout is messy or exceeds the view frame but I don't know how to define my constraints to make it work.
Like, is there a way to tell autolayout:
This trailing space should be 10 but if you can't then ignore it
Or something like that. Since I know which constraint should be ignored it would be great if there is a way to tell it to autolayout instead of having the warning and letting the OS "guess" which constraint to drop.
I am sure I could do everything programmatically by skipping all these constraints before animation, animating, and putting them back but since it is a big table view with many rows there are so many table view cell inner contraints to consider that it would really be hard to achieve.
Any insight / help / pointer on this would be great.
This trailing space should be 10 but if you can't then ignore it
The above statement is ambiguous, we need to define when the drawing system needs to add constraint for trailing space to 10 and when to ignore it, specifically.
This is obviously possible through coding it programatically. But,
You can set constraints using inequalities like "greater than or equal to" or "less that or equal to", and that would hopefully solve you problem.
Related
I am working on an iOS 11+ app and would like to create a view like in this picture:
The two labels are positioned to work as columns of different height depending on the label content. The content of both labels is variable due to custom text entered by the user. Thus I cannot be sure which of the the two labels is higher at runtime and there is also no limit to the height.
How can I position the BottomView to have a margin 20px to the higher of the two columns / labels?
Both labels should only use the min. height necessary to show all their text. Thus giving both labels an equal height is no solution.
I tried to use vertical spacing greater than 20px to both labels but this leads (of course) to an Inequality Constraint Ambiguity.
Is it possible to solve this simple task with Autolayout only or do I have to check / set the sizes and margins manually in code?
You can add labels to stackView
One way to do this is to assign equal height constraint to both label. By doing this height of label will always be equal to large label (Label with more content).
You can do this by selecting both labels and adding equal height constraint as mentioned in screen short.
Result would be some think like below
The answer given as https://stackoverflow.com/a/57571805/341994 does work, but it is not very educational. "Use a stack view." Yes, but what is a stack view? It is a view that makes constraints for you. It is not magic. What the stack view does, you can do. An ordinary view surrounding the two labels and sizing itself to the longer of them would do fine. The stack view, as a stack view, is not doing anything special here. You can build the same thing just using constraints yourself.
(Actually, the surrounding view is not really needed either, but it probably makes things a bit more encapsulated, so let's go with that.)
Here's a version of your project running on my machine:
And with the other label made longer:
So how is that done? It's just ordinary constraints. Here's the storyboard:
Both labels have a greater-than-or-equal constraint (which happens to have a constant of 20) from their bottom to the bottom of the superview. All their other constraints are obvious and I won't describe them here.
Okay, but that is not quite enough. There remains an ambiguity, and Xcode will tell you so. Inequalities need to be resolved somehow. We need something on the far side of the inequality to aim at. The solution is one more constraint: the superview itself has a height constraint of 1 with a priority of 749. That is a low enough priority to permit the compression resistance of the labels to operate.
So the labels get their full height, and the superview tries to collapse as short as possible to 1, but it is prevented by the two inequalities: its bottom must be more than 20 points below the bottom of both labels. And so we get the desired result: the bottom of the superview ends up exactly 20 points below the bottom of the longest label.
For the last few months I have been doing all of my layouts in code to practice with autolayout.
I have decided to go back to Storyboards and am regretting it already :-). I have been trying to do a layout with multiple views including a UIStackView and was getting many errors. I thought maybe I was doing something wrong with the StackView so I decided to delete everything apart from a button and label.
The simple view with a label and button can be seen below:
As you can see, the constraints on the label are very simple. The button in the top right (where the blue is) just has top space and trailing space. However when I run the app the label is not seen:
I am also constantly getting: An internal error occurred. Editing functionality may be limited.
Has anyone else experienced this odd behaviour?
You have set the leading and trailing of the label . This will definitely happen because you have set the wrong constraints. Check the size of your view Controller where you have set the constraints, its (Any width , Any height).
Now, check in which size you are running, its (Compact width, Regular height). If you run it in a iPad you will find your label. Since, you have not fixed the width of your label, the label gets compressed when it is run. Try setting the width of your label and remove either the leading or the trailing constraint.
Else instead you can fix your width and select either the leading and trailing and set it to "less than equal to " rather than "equals to".
While designing imagine yourself holding the object keeping in mind about all possibilities that can occur and then set the constraints accordingly. A user can run your application in any size iPhone and iPad. So, the design should be such that it doesn't affect your objects in it.
If any problem occurs try view debugging then you can definitely find out where you have done wrong.
You may need to remove label's leading & trailing space, and add add constraint call "Center Horizontally in Container" if you want to center the label.
You can learn more about autolayout in here if you do not know it well.
You have hard coded leading and trailing constraint constants. They add up to 518. That probably makes your label width negative. You don't see it in Storyboard because you're using the inferred simulated metrics. You'll see it right away if you change to an 3.5 inch iPhone.
I think a better approach would be to remove the leading and trailing constraints and center the label horizontally in the superview. You can set a fixed width on your label if you want.
I have previously worked in Windows phone and see that every control in windows phone has an Auto property, meaning occupy the size of the content.
I see that in iOS such a property does not exist. When there are dynamic data to be bound to a UILabel, I always need to calculate the height of the data and then assign to the UILabel. This takes a good amount of time and bit painful. Is not there an Auto property or am I missing anything here?
iOS has AutoLayout which is really helpful, get familiar with it.
Click on the Label
Click on the pin constraints button (little square button)
Add your custom LEFT, RIGHT, TOP margins or LEFT, RIGHT, BOTTOM margins
Click on "Add 3 Constraints"
Set number of Lines to 0 which means as much lines as view needs
Then you probably got warning lines, but you can solve them
Just click on fix constraints button (little triangle button)
Click update frames
UPDATE
Important: the answer to your question is to PUT NUMBER OF LINES TO 0 you can use that UILabel with 0 lines(which is autosizing) with frames and AutoLayout. AutoLayout is just a friendly suggestion that can be helful to setup views. Also put Line Breaking Word Wrap
Here you go also with some useful links for working with AutoLayout. AutoLayout is great because you don't care anymore what size is the screen, what orientation has the device at that moment. You just need to setup everything correctly and everything works amazingly but if your setup is wrong then AutoLayout might become your enemy. So start learning and experiencing right now.
Very good point to Begin learning AutoLayout
If Your are being lazy, start from video tutorial series
Great iOS7+ table view tutorial with autoresizing cells
Also check out this Stack Overflow discussion
You need to familiarize yourself with Auto Layout:
Auto Layout dynamically calculates the size and position of all the
views in your view hierarchy, based on constraints placed on those
views.
Just give top, left and right constraints and make label's numberOfLines to 0. That's it. Label's height will resize automatically.
I'm wondering if xCode auto layout / constraints are really as frustrating as I think, or am I just not understanding them. For example, I started with this basic label in the view controller:
Fair enough. A box with text that has equal margins on the left/right and a smaller top margin. Now when I run any size device, that gets skewed/cut off from the device view. So right away for some reason Xcode thinks that despite me putting the entire label in the view controller, it things it should display halfway off the screen. Don't get it but okay, so I went ahead and added auto layout constraits to the right, left and top margins. The result is:
So it centered it, which is nice, but now it just ignores the fact that I made the width larger and it just shrinks it down anyways? For something so simple this seems to be very...unreliable. I then added the "aspect ratio" constraint and it seemed to look fine in all of the devices...finally!
I curiously also simply tried to get rid of all those, and simply add the "aspect ratio" constraint and the "horizontal center in container" constraint. On the main storyboard preview (not the simulator) it looked like this:
Not what I'm looking for, as it's not stretched downward like I want, they shrunk it again. However...when actually running it in the simulator...it looks perfect, the way I want it to in the first picture of the view controller.
Why the preview and simulator differed, I suppose (from reading other questions) it's because there were a few warnings after I added these. One was that the horizontal and vertical positions are one initially and will be different at run time. But when I ran it, it definitely held the initial ones and not the ones they said it would be at run time. It also told me that vertical position was ambiguous...well yeah I only set a center and aspect ratio...pretty obvious and not sure how I'd even solve that error. It solves it when I delete the horizontal center...but now it's not centered which is a step back from what I wanted.
Long story short, how do I deal with this. My previews and simulations aren't accurate with each other even for the simplest auto layout specifics. Apps nowadays are so complicated and on every device they scale and work beautifully, and this seems to not agree with even just one label.
Does anybody have any good articles, advice, or anything that would help me? This auto layout stuff seems to be so picky and that's really all I know so I have to deal with it. And don't even get me started on why the text doesn't scale with the label...why would I want the text on an iphone 4 to be the same on an ipad even when my label is increasing in size with the device?
A lot to go through, but it's just very frustrating and I can't see myself doing much else before I try to understand these basics. Thank you and much appreciated.
I think you have to understand constraints first...without that you always made things frustrating....For understand the constraints you can check this links
http://www.raywenderlich.com/50317/beginning-auto-layout-tutorial-in-ios-7-part-1
http://mathewsanders.com/designing-adaptive-layouts-for-iphone-6-plus/
It takes a bit of experience to get used to it, but once you get it, you get it for good and it's very easy.
Basically the rule of thumb is don't trust exactly what you see in storyboard when it comes to the size of the actual object. Say you have a UIView centered horizontally and vertically in the main view. True it will try to keep the size of that UIView but center it in any size device, but I would never just leave it at that. I would either:
Add width and height constraints
Add a width/height constraint and an aspect ratio constraint
Add a width constraint and top and bottom constraints
Add a height constraint and leading and trailing constraints
Add top, bottom, leading, and trailing constraints
In other words, the exact size of the object should always be determined via the constraints, and not by the UIView itself. This gets away from the finicky behavior and also ensures that it's displayed on any device exactly the way you intend it to.
I have been struggling for days with this implementation, and even though I have tried to do every tutorial I found on the web, I still cannot make things work the way I want.
Basically, I am trying to put my login form in a scrollview, so that it takes the whole screen at first (and on all iPhones / iPads), and if the keyboard appears everything should move. The problem IS, my view doesn't take the whole screen... Either it is too large, or too high, even though in Interface Builder everything seams correct (from layout to constraints). Below and image of the layout I want to achieve (I am using an universal storyboard, with Size Classes and Autolayout enabled):
http://img4.hostingpics.net/pics/829115app.png
Can someone point me out on achieving this layout ?
Thanks in advance.
I would suggest pinning top, leading and trailing spaces of your scroll view to its superview. And set a bottom space constraint less or equal to the keyboard's height if you set it to 0, the scroll view won't be able to resize.
With your form layout set vertical center constraints and top space to superview constraints for your top label being more or equal than the distance you set in the IB, and then you can set relative space constraints between each of the components.
Hope I answered your question.
Edit: Just the provided project and got it working. I think the problem is caused by it being a containerView inside a scrollView. And both the container and the scrollViews content view adapt to the size of its subviews. Because of that, setting relative constraints won't help.
What I did was to set an explicit size (screen's size) to the containerView and setting setTranslatesAutoresizingMaskIntoConstraints(true) to it.
I modified your project and uploaded it here