I want to add code to the back button presented in UINavigationController. But, I want the back button to look identical to what Apple presents.
I have this all setup to use my graphic in the leftBarButton, but am unable to get the graphic to look perfect. To that end, is there a way that I can use the internal iOS back button in my own custom button?
Unfortunately the navigation bar's back button is not very customizable. There is no simple way to access this image.
If you're familiar with Sketch or Photoshop, I suggest you take a screenshot of the back button and trace your image over the exact location.
If you can't do this, you technically can access the back buttons image through some minor UI manipulation. You'll have to first have a back button which is on screen. Once you know it's on screen, such as in your viewDidAppear, you'll want to look through the subviews of your leftBarButtonItem. One way you can do this is by calling navigationBar.subviews and navigating until the view. Another way is to expose the items target view.
extension UIBarButtonItem {
var targetView: UIView? {
guard let view = value(forKey: "view") as? UIView else {
return nil
}
return view
}
}
Now you can call leftBarButtonItem.targetView.subviews. Your for-loop would look something like,
for subview in leftBarButtonItem.targetView.subviews {
if let imageView = subview as? UIImageView {
self.image = imageView?.image
}
}
All of this is pseudo code and untested. Typically UIKit will use the standard classes (such as UIImageView) when building their views. However in older classes, they have been known to draw images manually. So if there is no image, you can always resort to taking a snapshot of the view with the arrow.
view.snapshotView(afterScreenUpdates: false)
Once you have your image / view, you'll save it in a property (most likely in your custom navigation controller) and then you'll have access to it whenever you push new view controllers.
Related
What I want to to: I want to drag down the whole view of a viewController to dismiss to the parent viewController using a pan gesture recognizer.
The Problem: When I drag the view down, the navigationBar decreases its height and does not look good. When the view returns to its original position, the navigationBar returns to the default size. I want the navigationBar to stay at its size. I also tried to use the new large titles and some other properties of the navigationController/-bar, but that did not solve it.
Note: Everything worked fine already before iOS 11.
My code:
override func viewDidLoad() {
super.viewDidLoad()
let panGesture = UIPanGestureRecognizer(target: self, action: #selector(dragViewDown(_:)))
navigationController!.view.addGestureRecognizer(panGesture)
}
#IBAction func dragViewDown(_ gesture: UIPanGestureRecognizer) {
if let dragView = gesture.view {
let translation = gesture.translation(in: dragView)
dragView.center.y = (dragView.center.y + translation.y)
gesture.setTranslation(CGPoint.zero, in: dragView)
}
}
This test project only has one viewController and does not provide the dismissal, but the problem is the same as in my working project.
I also uploaded the project to GitHub: https://github.com/maddinK7/navitationBar-pull-down-problem
Does anyone have an idea how to solve this? Thanks in advance.
I want the navigationBar to stay at its size
It is staying at its size. If you check the navigation bar's bounds size height before, during, and after the drag, you will see that it remains the same (probably 44) at all times. What's changing is the drawing extension that causes the drawing of the nav bar to extend up behind the status bar. It can't do that when you pull the whole thing away from the top of the screen, because it is not at the top next to the status bar any more. iOS 11 is more strict about the way it performs this drawing extension, probably because it has to do it in a special way on the iPhone X.
So, let's make sure you're doing this correctly:
Make sure that the navigation bar has a top constraint pinned to the safe area layout guide's top, with a constant of zero.
Make sure that the navigation bar has a delegate that returns .topAttached from position(forBar:).
If you are doing both those things and it doesn't help, you'll have to implement this in some other way entirely. Making the view directly draggable like this, without a custom parent view controller, was always dubious.
When UINavigationController attached top, system will add safe area top margin in the navigation background.
(NOTICE: Background margin will not changed when offset value is between 1 and 0)
So you have to handle attached/detached top event by handle gesture offset to change the right offset and content insets.
You can try the solution in my lib example. ;)
My example include UITableViewController in the UINavigationController, so it will relatively complex.
https://github.com/showang/OverlayModalViewController
I mean, not a UITabBarItem, an UIButton. For example, in the Deezer app, the middle button shows a view with an animation that covers the entire screen. I don't want the button to be rounded. Just to execute the action.
This is a very simplistic example. You'll still have to modify it to fit your needs, but if you have a UIBarButtonItem called button that you've added to your navigationBar, you should be able to do something like this, in viewDidLoad
button.action = #selector(showView)
Then you just need to create a function to be called.
func showView() {
let myView = UIView()
self.view.addSubview(myView)
}
Of course this has no animations, but again this is just to point you in the right direction.
Having a very weird behavior on iOS 10. Assume you have an empty app, created with a Master-Detail Application template. Place any UIView as a titleView in navigationBar for detail viewcontroller. Place any UIView to the right bar button items.
Then, write that code to configureView method:
if let item = self.splitViewController?.displayModeButtonItem {
self.navigationItem.leftBarButtonItem = item
self.navigationItem.leftItemsSupplementBackButton = true
}
Then configure splitviewcontroller preferredDisplayMode = .allVisible, so the displayModeButtonItem could appear.
On iOS 9 and lower this results in a standard behavior: the detail viewcontroller displays displayModeButtonItem expand button on a left side.
When user taps it, the icon transforms to an arrow. Tapping an arrow reverses button state.
On iOS 10 displayModeButtonItem displays as expand button, but if user taps it, it disappears.
Meanwhile, the button is still there and a user can tap it one more time. After that, displayModeButtonItem appears again with expand icon and backButtonItem icon as well. Just like it appears when we push another viewcontroller onto detail's navigationcontroller:
But in that case both of icons acts as displayModeButtonItem.
Is this an iOS bug, or a misconfig? What can I do to get normal button behavior?
Edit: I found out, that everything works as expected, if a titleView (of rightBarButtonItem's view) does not contain any constraints on it's child views. Filed a radar on this.
Edit 2: Some controls (like UIImageView) may implicitly add NSContentSizeLayoutConstraint, so, to prevent this behavior (and prevent the bug above), subclass it and override intrinsicContentSize method like this:
private class NoConstraintsUIImageView: UIImageView {
private override func intrinsicContentSize() -> CGSize {
// prevent implicit NSContentSizeLayoutConstraint adding in updateConstraints
return CGSize(width: UIViewNoIntrinsicMetric, height: UIViewNoIntrinsicMetric)
}
}
I'm trying to add a sliding photo gallery functionality to the top portion of a view.
To give context, a user taps on a button or row or something. Then i load a scrollview with a uistackview in it. organized vertically, i had an image, and then another stack view with some text in it. Now, i want that image to become part of a larger "gallery". My research told me to implement UIPageviewcontroller and add the other images to a childVC.
i used this as a tutorial (the first example): http://www.raywenderlich.com/76436/use-uiscrollview-scroll-zoom-content-swift
the only relevant deviation from the tutorial my app has is that it creates things programmatically.
With my proof of concept for the gallery functionality, i wanted to integrate it with the previously mentioned stack view. my plan was to first add the pageviewcontroller stuff into the overall stack view with the original image view right below it and then simply remove the original image view to leave me the final product.
i was able to add the pageviewcontroller.view to the stackview, but the gallery doesn't show. taking a look at the UI Inspector, i can see that the gallery is kinda loaded, but it's messed up.
it's as if the uiview has a frame of 0 height and so the other stack view items don't respect the images that the pageviewcontroller is trying to show.
I think it could be that stack views can only handle specific views, not stuff as complicated as pageviewcontrollers.
also note: my implementation is all programmatic, no storyboards, and so for no xibs. so maybe i missed something here.
here is some code, if it helps:
note the constrain functions you see are from the "cartography" pod
this adds the "gallery" to the stack view, it's a delegate function from my view
func addZoomStuff(sender: UIStackView) {
let zoomer = PageBaseViewController()
addChildViewController(zoomer)
zoomer.view.translatesAutoresizingMaskIntoConstraints = false
zoomer.view.tag = 5
sender.addArrangedSubview(zoomer.view)
zoomer.didMoveToParentViewController(self)
}
this is what creates the scrollview, image view, etc for the gallery items:
override func viewDidLoad() {
super.viewDidLoad()
//MARK: - Zoom View Elements
// prep
scrollView = UIScrollView(frame: self.view.frame)
scrollView.delegate = self
self.view.addSubview(scrollView)
constrain(scrollView, view) { view, view2 in
view.edges == view2.edges
}
self.view.setNeedsUpdateConstraints()
// 1
let image = UIImage(named: imageName)!
imageView = UIImageView(image: image)
// 2
scrollView.addSubview(imageView)
constrain(imageView){ view in
view.edges == view.superview!.edges
}
scrollView.contentSize = image.size
i tried adding the constraints like this but there was no effect
func addZoomStuff(sender: UIStackView) {
let zoomer = PageBaseViewController()
addChildViewController(zoomer)
view.addSubview(zoomer.view)
constrain(zoomer.view, view) { view, view2 in
view.width == view2.width
view.height == view2.height * 2 / 3
view.leading == view2.leading
view.top == view2.top
}
zoomer.view.setNeedsUpdateConstraints()
zoomer.view.removeFromSuperview()
zoomer.view.translatesAutoresizingMaskIntoConstraints = false
zoomer.view.tag = 5
print("sender.subviews: \(sender.subviews)")
sender.addArrangedSubview(zoomer.view)
zoomer.didMoveToParentViewController(self)
print("sender.subviews: \(sender.subviews)")
}
if this method isn't going to work, can i do a nested horizontal stack view instead of the pageviewcontroller and somehow get that same scrolling/snap effect to see on image view at a time?
TLDR;
Create a subclass of UIPageViewController, make it it's own delegate.
Initialize the subclass with a plain UIViewController, only set a backgroundcolor.
In the pageviewcontroller subclass, implement the two delegate callbacks for a next and previous viewcontroller: create a plain viewcontrolller, with some random backgroundcolor.
If this works, replace the plain viewcontroller by your actual contentviewcontroller.
Long version:
Have you seen this: Maybe this link will help: https://developer.apple.com/library/ios/documentation/WindowsViews/Conceptual/ViewControllerCatalog/Chapters/PageViewControllers.html
It might help, as it explains the details of UIPageViewController. Basically, you need to create a viewController (not a view!), that shows one page of the gallery. So this VC has a stackview, and manages the content of it. The pageviewcontroller is initialized with your first contentviewController. If you create a subclass of the uipageviewcontroller, you can set self of that subclass as the delegate of it. Implement the delegate callbacks that return the next or previous viewController and thats it. For this last part, it is convenient to have a property on the contentviewcontroller from which the subclasses of the pageviewcontroller can figure out what data to set on the next or previousviewcontroller.
Your title seeks to hint at some confusion: its not possible to add a viewcontroller to a view. You can only add other views to a (stack)view. A viewcontroller owns and manages a viewhierarchy. A pageviewcontroller has no content, but manages the insertion and removal of viewcontrollers. as the pageviewcontroller is a containerviewcontroller, it will als take the contentViewcontrollers' views and place them in the viewhierarchy. But this is not something your code has to do when you subclass UIPageViewControlller and implement it's delegates on itself (and don't forget to assign self to be the delegate).
If you look at this image (I don't want to upload it, as it does not belong to me), you will see what appears to be a uiview inside the main uiview controller in the settings app of an iPad. My question is, how do I replicate this programatically? In other words, how do I embed a UIView in another?
Here's what I know and have done:
Based on my research, this is called "subviews". Is this correct?
I have created a UIView with the proper elements that I want in interface builder. It is currently not a subview, but at the same level hierarchically as my main view.
I found the same exact question except in Obj-C, not my language (Swift).
Here's what I need:
How do I programatically spawn a subview in swift once a button is clicked?
As this subview is pretty complex in terms of UIelements, I want to be able to design it in interface builder.
Here's what I have so far:
#IBAction func buttonPressedSpawnSubview(sender: AnyObject) {
//Open a subview from Interface builder.
}
#IBAction func closeButtonPressedSpawnSubview(sender: AnyObject) {
//kill the subview.
Can someone help me figure out how fill in the commented lines?
What you are seeing is a modal UIView on top of another view.
An example from within your visible ViewController would be:
self.modalTransitionStyle = UIModalTransitionStyle.FlipHorizontal // Choose whatever transition you want
self.modalPresentationStyle = .CurrentContext // Display on top of current UIView
self.presentViewController(yourNewViewObject, animated: true, completion: nil)