Autolayout causing UI Elements to "snap" into place at runtime? - ios

I have a UIView with a UIImageView at the very top, a UILabel below it, a UIButton below that, and a UISegmentedControl that determines what determines what embedded UIview to display at the bottom (which also a choice to not show any at all).
I've run into the problem where I've set up all of my constraints in the interface builder, and everything seems to be fine when I switch between screen sizes in the storyboard. However when I actually run the project on a device or emulated, the UIimage at the top is briefly stretched before "snapping" into a size the fits the constraints. Also, it seems as if the label disappears for a brief second and reappears after the image has snapped into a size. After the "snap" has occurred, everything is in place and there are no problems.
This snapping occurs both when testing on a 4 and 3.5 inch display. I find this odd because I've designed the UI for the 4inch screen perfectly.
Does anyone know why this is happening?
Edit
Here's whats the constraints look like in IB.

This is potentially due to adjustments that you might be making to your UI elements (or constraints) from the view controller in code. For example, if you are programmatically setting a different UIImage into your UIImageView, and this code is happening too late in the view lifecycle (for example, in viewDidAppear) after a layout pass has already calculated view positions and sizes, then you will see a visible snap as views take on new positions based on the new intrinsic content size of the image view.
This could be caused by other adjustments such as injecting a localized string into a UILabel in code, which causes the label to have a smaller or larger intrinsic content size, which in turn affects the layout based on your constraints.
If you are making adjustments to your UI in code, make sure they are happening in viewDidLoad or viewWillAppear: so that they occur before the view's initial layout pass (and the view's animation onscreen).
If you're still seeing issues, you can try explicitly forcing an immediate layout pass to occur on the view controller's view at the end of viewWillAppear: by doing the following:
- (void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
[self.view setNeedsLayout];
[self.view layoutIfNeeded]; // forces an immediate layout pass
}

Spacing between the UIElements might be the problem . Specially when using Pickers

Got it, You have applied constraint for Picker to adjust along with segmented control. So when app runs on 4 inch screen , picker automatically fits properly, but for 3.5 Inch picker always starts from bottom of the screen and picker will push segmented control upwards and hence segmented control will push rest control automatically.
Remove picker and segmented control constraint.

Related

UIPickerView ignoring contraints

I have a view within my app that has a UIPickerView. The delegation and datasource is set up and the picker loads data correctly, however, it ignores storyboard constraints entirely and shifts to the top of the view regardless of what I've tried.
The screenshots below show the alignment in storyboard (the picker is aligned center vertical/horizontal to the blue view (which has a constraint of 30 on all sides) and the alignment when the app is run on a 6S.
Any idea what I'm doing wrong?
UIPickerView has a fussy implementation of setFrame: -it only allows itself to be rendered in a handful of sizes. The easiest way to control/overcome this is to put it in a container view and apply your constraints to that view. You could override layoutSubviews in that containerView in order to center the picker, perhaps even applying a transform to scale it. Don't try to set the size of the pickerview in this code, just query (get) it and then calculate around that value.
Remove [self.view addSubview:self.mouthpiecePicker]; This is re-adding the picker view, but it was already added with Storyboard. When you re-add it, it removed all constraints.

iOS - viewDidLayoutSubviews called before auto-layout completed on iOS7

We're currently having a problem that only seems to affect iOS7 devices.
Within our .xib file we have two views within a container view (i.e.: not at the top level of the view hierarchy) that need to be circular on display. The views have constraints applied to their position and horizontal spacing within the container, and an aspect ratio condition requiring they are square. The views should expand in width/height on larger screen sizes, respecting the constraints described.
In our VC, we have the following in viewDidLayoutSubviews to force these views to appear circular:
- (void)viewDidLayoutSubviews {
self.progressContentContainerView.layer.cornerRadius = self.progressContentContainerView.frame.size.width/2;
}
This seems to work fine on iOS8, however on iOS7 there is a period after the view has been displayed where the constraints have not yet been applied and the size of the view/views is incorrect (see attached screenshots). This resolves itself and correctly renders a circle after half a second. This only appears to happen when the views that we intend to be circular are NOT at the top level of the VC's view hierarchy which seems to imply that viewDidLayoutSubviews is called before the subviews of subviews have also been laid out.
My guess is that we could potentially fix this issue by subclassing UIView for the nested container, adding references to the circular view within this subclass and overriding viewDidLayoutSubviews here to make the cornerRadius adjustment. This seems like a bit of a workaround though and I'm interested to see if there are other options.
Is there a cleaner/more idiomatic solution to this problem?
I know this is an old question but have you tried calling either:
[self.progressContentContainerView setNeedsUpdateConstraints];
or:
[self.progressContentContainerView layoutIfNeeded];

Xcode 6.1 IOS really long form

I am quite new to xcode.
I am trying to create a contact details form for an iPhone using the storyboard. The problem is that form is longer than the display and I can't work out how to design it using the storyboard.
Any ideas?
Tom
In IB, you can set the controller's size in Simulated Metrics to Freeform, then select the view and make it as tall as you want. Then, add a scroll view to take up the whole view, and add your UIElements, and lay them out how you want. When you run the app, the view controller will still only be as big as the screen (obviously), but the scroll view will be as big as you made the view in IB (you may need to increase its contentSize even more to be able to scroll to the bottom).
Such forms are often made in storyboards using a UITableView and setting the "content" of the table to be "Static Cells." You can set any number of cells and the contents of the cell you want. The table itself is scrollable inside the storyboard/Interface Builder editor and looks much the way it would when presented to a user.
First, select the tableView on the left
Then, you can move it simply scrolling (on mac, two fingers on the trackpad, or using the mouse wheel)
You should have a look at UIScrollView, it is designed to support content larger than screen size (like you see in web browser or settings)
Basic usage is:
//Set a size which will be able to cover all form elements
[yourScrollView setContentSize:CGSizeMake()];
//Your scrollView now extends from CGPoint 0,0 to contentSize.width,contentSize.height.
//Your subviews should be positioned according to scrollview's bounds not the viewcontroller.view or any other container view.
//Add all the form elements
[yourScrollView addSubview:...];
[yourScrollView setDelegate:self]; //If you need actions after user scrolled etc.
Have a look at the developer manual for more info. Most method names are quite self explanatory.
http://developer.apple.com/library/ios/#documentation/uikit/reference/UIScrollView_Class/Reference/UIScrollView.html

Using UIScrollview in iphone5 compatible app

I have a problem adapting my apps to the new iphone5 layout, I've made the following passes:
Added a retina 4" splash image
Modified the interface in my storyboard with "Size inspector" to change the anchoring of the widgets
Tested the app with iOS6 "retina 4" simulator.
The app works as expected except when the user pop up the keyboard to edit a text, I use the "stretching scrollview" method for this particular situation and this seems not compatibile with the "autosizing" properties of my widgets, here is an example, from iOS6 simulator, without and with keyboard:
And here is what happens:
I'm quite sure this is a coherent behaviour since my main view is stretched so the other items inside it are stretched following their anchoring, the fact is that I'd like to have the same behaviour of my previous fixed position (all widgets anchored to the top left corner) with the iphone5 gui expansion, is this possibile?
How do you solve the problem of showing a keyboard and scroll hidden content in an iphone 5 compatible way?
I have been having similar problems. From what I have found thus far, we may need to remove all constraints on the view within the scrollable view, because it appears that it's contents are being resized along with the frame of the scrollView. I know that setting the internal view's frame manually in viewWillAppear will work, but then you are stuck having a view that is the same size for both iPhone4 and iPhone5 (albeit it will scroll). Or you could "pin height and pin width" of the internalView right there in storyboard.
Two potential approaches that may work. Sorry I can't confirm these as I'm giving up and redesigning around this problem.
1. Programmatically add constraints to your internal view's subviews. The programmatic constraints will allow you to "spring" the distance between your elements proportionally. When adding constraints programmatically, you are given access to a factor called "multiplier" (not to be confused with priority), which I saw someone else on stackoverflow posting about.
2. You can design the internalView in Interface Builder as a separate viewController with it's .xib file, and then use storyboard to load it as an embedded viewController to a "containerView" object, which you would put in place as the new "internal view" of the scrollView. Perhaps then the .xib would first resize to the correct iOS device, and then you could use its frame to resize the containerView.
My advice is create a small test-case of these before implementing, else you end up like me, having spent hours down the wrong path and facing a dead-end.
UPDATE 12/4/12
Make your life easier by NOT setting the ScrollView as the main view of the ViewController.
--Instead, make ViewController.view a dummy/blank view, and embed a scrollView inside that view. Then, embed another view (my CustomView) in the ScrollView. CustomView contains all the visible controls and text boxes and buttons. There is NO HEIGHT CONSTRAINT on CustomView.

Designing inside a scrollview in xcode 4.2 with storyboards

I have a vertically scrolling uiscrollview - imagine an 'about this app' page of a tab bar app which goes on a bit and requires a scrollview. It only contains a few images, a video and some text (only the video has been coded in - the rest have been placed in the GUI). In storyboard (Interface Builder?) Xcode 4.2, everything is set up as it should be and works fine, but the view is only as large as what you see on the screen, is it not possible to manually arrange in storyboard the items that are initially offscreen - that you need to scroll up to? The only way I've found so far is to design them on the visible view then navigate them down with the arrow keys..
In the storyboard select the viewController, then in Attributes inspector change 'size' to 'freeform'. Then change the 'height' of the view/scroll view to as big as you need. The default settings of struts and springs should take care of resizing the view back correctly when the app is run, but you should double check.
I feel your pain. The only way I found is to manually pan the scroll view in the size inspector to reveal the portion of the view that you wish to visually edit.
Use a UIView to contain elements so they are positioned relatively to this view. Add the view as a subview to the scrollview at 0,0.
pan: use the Y coordinate say to -200, then edit the contents.
to place more contents in the hidden part, pan again to reveal new real-estate
when finished, restore the values of the ScrollView's height and X,Y position.
Make sure the scroll view frame rectangle is smaller than the contained view.
New: 3/26/2013
I stumbled upon what I think is even simpler way of dealing with UIScrollView directly in storyboard.
No code needed, just storyboard settings. This maybe new in iOS6.1 / Xcode 4.6
No need to disable constraints (i.e. uncheck "Use autolayout" in File Inspector for storyboard file)
No need to add UIScrollView* scrollView; in .h
No need to add self.scrollView.contentSize = ... in overrides of viewWillAppear or viewDidLoad
Here is what I did (important parts highlighted with **): (see code)
Create a new project with storyboard enabled
Drop in a UIScrollView, set class in identity inspector for view controller
In attributes Inspector, change Size under simulated metrics to Freeform**
Select scroll View; In attributes inspector, turn on "scroll enabled" and "background" to "White" (you'll figure out why - if you don't)
Under Size Inspector (with scroll view selected) change the height to 900 for example**
Add buttons, one on top and one at the bottom
Add a default handler for buttonTouchUpInside for both buttons and simply Log sender.
See Code Select the View Controller and scroll view and check inspectors.
Just change the 'Simulated Size' of the view controller to freeform and set a height that is larger than the usual size, you will be able to see all the outlets you need to edit.
On iOS 6.0 you can drag a Container View inside your Scroll View. This will automatically create a new View for your content, outside of the current scene. You can then resize this view as big as needed to fit your content.
I believe you would still have to set the ScrollView content height at runtime, but at least you can design you content view at once without having to scroll up and down on IB.
Just uncheck the "Autoresize subviews" from any view that you're trying to resize and it should keep all your objects from resizing with it.
I've been struggling with this for a while now, and every single thing I've tried has failed.
Specifically, What I am trying to achieve is a freeform sized modal dialog with a scrollable view containing a container for another view. I have had a lot of varied results, including occasionally having it working correctly. Most often I get it looking exactly correct, but with no scrolling.
In finally downloaded Dickey Singh's code, which worked perfectly but had nothing special. (Excellent clean solution BTW). So, I added a container view to it, exactly as I had in my code, and it broke!
After some experimenting, I worked out what is going on. Just bear with me.
1) Using Auto Layout, the size of the scroll view seems to dictate what the scrolling bounds will be. Setting "contentSize" in "USer Defined Runtime Attributes" seems to have no effect on this, and neither does setting "contentSize" or "bounds" in "viewWillDisplay" or "viewDidLoad". Thus if the initial size of the scroll view is 800x800, that will be all the space that can be displayed. For this reason, when I want a scrollable region, I create a container view and then put the scrolling view inside the content.
2) Without Auto Layout, setting "contentSize" in "User Defined Runtime Attributes" works, as does by setting it programmatically in "viewDidLoad". I prefer to use "User Defined Runtime Attributes" because it keeps the size with the layout. This solution allows you to use scrolling view with more flexibility, since it can be any size at design time.
3) Regardless of Auto Layout, if any view within the scrolling region exactly matches EITHER the horizontal or vertical frame bounds, then the scroll view ceases to function as a scroll view. This applies to my own code and to Dickey Singh's code in every possible configuration that I have tried.
I have no idea what is causing (3), but it is clearly a bug.
I hope this helps everybody out there who is struggling to use scroll view. I imagine that some people are using them without any problem, and some (like me) have had noting but problems with them.
Here's my solution to design a ScrollView with a content larger than the screen entirely in Storyboard (well, except for 1 single line of code :-) :
https://stackoverflow.com/a/19476991/1869369
I'm currently developing an app for iOS 7, and I did exactly as #Dickey Singh's answer, but it doesn't work in the beginning.
After checking the storyboard, I found that we also need to add Auto Layout Constraints for the view controller who holds the scrollView.
It seems that such auto layout constraints would be added automatically before Xcode 5, but now we need to do it ourselves.
The way to add constraints: First select the view controller in the storyboard; Enter 'Editor' in the top menu; Select the 'Resolve Auto Layout Issues'; Select the 'Add Missing Constraints In Container'. Done :-)

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