I know that the component List has an UITableView behind. I also know I can change the background by changing the UITableView.appearance().backgroundColor.
What I want is to change this for a single View that has a List component, without affecting the rest of the application. Is this possible? If so, how?
Thanks!
This is what I know needs to be done to achieve this:
var body: some View {
List {
//Your content
}
.onAppear {
//The specific table view settings.
//UITableView.appearance().separatorColor = .black
}
.onDisappear {
//The general table view settings
//UITableView.appearance().separatorColor = nil
}
}
But it is problematic for several reasons.
The biggest reason is the fact you might have 2 table views in the same View and you want them to have different appearances.
The second issue is that not all cases will call onAppear (I don't remember specific cases but I remember having issues with TabViews)
I hope there's already a better solution waiting in the next version of SwiftUI.
Related
Main Question
Sorry for the long title. I’m trying to figure out how to provide a choice to user’s for setting the ColorScheme of the app to ‘System’.
As in, have the app default to the system’s dark mode / light mode. I know UIKit has a way to set the style to .unspecified but I’m not sure how to access that in SwiftUI.
I already tried setting .preferredColor() to nil and it kind of sort of works but sometimes it doesn’t. I’m new to managing state in Swift so I’m definitely doing something wrong.
Side Question:
When I set .preferredColor() to say .dark - the modal settings sheet I have doesn’t update? It always stays the system colour. I have .preferredColor() triggering on the ContentView() in the ...App.swift file.
Update
I solved my Side Question by just adding .preferredColor() to the modal sheet as well. It's not ideal but it does work. However I'm still unable to figure out how to set a .system preference in SwiftUI
I ended up finding two solutions to this problem. The first was found by jinjie and the other by me. Both solutions can be viewed here - repo. created by rizwankce.
Solution
What I ended up doing was using the package Introspect to grab the UIViewController off the main view I have using a ViewModifier.
Within the ViewModifier I just used .introspectViewController and that gave me the UIViewController so that I could then set UIViewController.overrideUserInterfaceStyle = .unspecified like this. Then I just did this conditionally based on a Picker not seen below. ⤵
/// All themes
enum Themes: String {
case Dark
case Light
case System
}
// MARK: - Theme Switch
struct ThemeSwitch: ViewModifier {
let appStorage: String
func body(content: Content) -> some View {
content
.introspectViewController { UIViewController in
switch appStorage {
case Themes.System.rawValue: UIViewController.overrideUserInterfaceStyle = .unspecified
case Themes.Dark.rawValue: UIViewController.overrideUserInterfaceStyle = .dark
case Themes.Light.rawValue: UIViewController.overrideUserInterfaceStyle = .light
default: UIViewController.overrideUserInterfaceStyle = .unspecified
}
}
}
}
// MARK: - Extensions
extension View {
func themeSwitch(appStorage: String) -> some View {
modifier(ThemeSwitch(appStorage: appStorage))
}
}
I just stored the desired theme as a String into a #State object which also updated an #AppStorage object so the app always had the selection no matter what.
You don't have to use Introspect and could instead create your own wrapper but I already had this package installed so I figured why not.
Alternative Solutions
The other solution is to make a view modifier and display the modified view conditionally. The condition is based on an optional array, dictionary, etc. of type ColorScheme. It either unwraps the optional if it's not nil or it just shows the unmodified view. You can find it at the repo. mentioned above under closed issues or pull requests.
In the future hopefully Apple will provide a way to do this natively but for now this will do! I'll try to update this answer in the future if something better comes along.
Swift 5.2
I have a NavigationView, for a tree of Views joined by NavigationLinks. (No weirdness going on; no cycles or hopping between different parts of the tree - just views linking to subviews linking to subsubviews.) One of them is a configuration screen. I desire that when you arrive on the config screen (aka ConfigView), the configuration is loaded from disk. In subviews of ConfigView, you can modify different settings, and on ConfigView you can save the settings. However, I desire that if you pop ConfigView (leave, towards the root of the tree), your unsaved changes are discarded.
One of my initial thoughts was to load the changes in the ConfigView initializer. This doesn't work, because ConfigView() is called in the parent view, so exiting the ConfigView and returning to ConfigView keeps the same ConfigView between views (and thus the same dirty data). (...Or, the ConfigView is recreated multiple times without actually leaving it, causing the data to be erroneously reloaded. I tried to test the conditions under which it did either, just now, but ran into a crash I'm not going to fix today. Regardless, I tested it earlier today and it demonstrated one or both of the above behaviors.)
Perhaps load it in the body block? But that gets re-run e.g. when you return from a subview link, which would erroneously reload the data.
Perhaps load it in .onAppear? But that ALSO erroneously reloads the data when you return from a subview.
I considered perhaps going with the dual of my original intent, disposing of the dirty data when you pop the ConfigView (and reloading it whenever requested), but I haven't found any hooks I can use to be notified when e.g. the user hits the "back" button.
How do I get a clean copy of the data to be present on new entry to the ConfigView, and not lost until the ConfigView is popped?
You should have a persistence data somewhere in your app, and when passing data to a child view create a draft data (ObservableObject). Then, save the updated data to the persistence data whenever needed. This way, the child will only play with the draft data and your parent view will only show the persistence data.
There's a good example here: https://developer.apple.com/tutorials/swiftui/working-with-ui-controls
Please have a look at all of the tutorials made by Apple, they are very short and powerful samples.
I will paste the code from the link above to here just in case the code is lost sometime in the future.
struct ProfileHost: View {
#Environment(\.editMode) var mode
#EnvironmentObject var userData: UserData
#State var draftProfile = Profile.default
var body: some View {
VStack(alignment: .leading, spacing: 20) {
HStack {
if self.mode?.wrappedValue == .active {
Button("Cancel") {
self.draftProfile = self.userData.profile
self.mode?.animation().wrappedValue = .inactive
}
}
Spacer()
EditButton()
}
if self.mode?.wrappedValue == .inactive {
ProfileSummary(profile: userData.profile)
} else {
ProfileEditor(profile: $draftProfile)
.onAppear {
self.draftProfile = self.userData.profile
}
.onDisappear {
self.userData.profile = self.draftProfile
}
}
}
.padding()
}
}
I want to update a SwiftUI List without any insert animation.
My List is getting its data from an #EnvironmentObject
I already tried to wrap the List itself and the PassthroughSubject.send() in a withAnimation(.empty) block but this does not help.
A very very dirty workaround is to call UIView.setAnimationsEnabled(false) (yes, UIKit has impact on SwiftUI), but there must be a SwiftUI-like way to set custom insert animations.
While the answer provided by DogCoffee works, it does so in an inefficient manner. Sometimes we do have to force the system to do what we want by being inefficient. In the case of implicit animations in SwiftUI, there is a better way to disable them.
Using the Transaction mechanism in SwiftUI, we can define an extension that can be applied to any view. This will disable animations for the view and any children.
For the list view example, this avoids replacing all the data in the list with a new, but identical copies.
extension View {
func animationsDisabled() -> some View {
return self.transaction { (tx: inout Transaction) in
tx.disablesAnimations = true
tx.animation = nil
}.animation(nil)
}
}
Try applying this extension to your list, or the parent containing view. You may have to experiment to find which view is ideal.
List {
// for each etc
}.animationsDisabled()
This works, just place .id(UUID()) at the end of your list
List {
// for each etc
}.id(UUID())
Sort of like reloadData for UIKit
on tvOS this works for me:
List {
...
}
.animation(.none)
.animate(nil)
you can find more info on https://developer.apple.com/tutorials/swiftui/animating-views-and-transitions
I am creating a framework for the other apps to use it. I want to find when the display presented to the user changes. These changes include addition and removal of subviews, scrolling down, adding text, etc. Is there a way I can directly check when the content presented on the screen is changing. Above question is a part of the problem.
Did you mean viewDidLoad?
That function called first time after all view loaded same as ViewTreeObserver.OnGlobalLayoutListener.
After you explanations I would simply do something like this:
class MyViewController:UIScrollViewDelegate{
func addSubview(){
self.takeSnaphot()
}
func scrollViewDidScroll(scrollView:UIScrollView){
self.takeSnaphot()
}
func takeSnaphot(){
//the code to take snaphots
}
}
I'm looking for a way to show a UIView "InventoryView" in 2 view controllers.
I'm working on an inventory system for my game that I trying to make but I need to be able to access it from my main view, where it will go to a InventoryViewController (in this ViewController is my InventoryView) but I also need to be able to access the InventoryView from my BattleViewController where it does not go to my InventoryViewController but where it print the InventoryView on my BattleViewController so I can access everything durning the battle.
Example:
(evrything is dragand drop, the UIView and the UIButtons)
InventoryViewController
class InventoryViewController: UIViewController {
class InventoryView: UIView {
//here are some UIButtons and labels
}
}
BattleViewController
class BattleViewController: UIViewController {
class InventoryView: UIView {
//it should print the Inventory Screen on my BattleViewController
//here are the same properties as it shows in the InventoryViewController
}
}
This is a great example to look at the way OOP programming works best.
Ask yourself the following questions:
What is the purpose of the view?
Are the interactions on the view homogenous across all the instances? (touch events, specific behavior, etc...)
What is the minimum amount of information you need to make the view look the way you want?
Once you have those answers, you can approach the concept of reusability of views safely.
The way to go about it is to subclass UIView, create the necessary elements of your view, setup your constraints (still in the view, either in a nib or programmatically), and implement any behavior that will be consistent across views (For example if the view is a segmented control, every time you click a segment all the others go grey and the one you clicked go blue. Since that's the primary purpose of the segmented control, the code for it should belong to the segmented control).
Chances are you will find the docs very useful: https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIView_Class/
Lastly write a setup method that takes all the information you need and sets up all your graphical elements accordingly. Remember, views should never own their data (they should be templates, the controller will provide the data).
I have no idea what you view looks like but I assume the inventory is represented as an object. Then something like could be a good start:
class InventoryView: UIView {
var inventory: Inventory? {
didSet {
if let newInventory = inventory { //in case we set it to nil
setup(withInventory: newInventory)
}
}
}
private func setup(withInventory inventory: Inventory) {
//do your setup here
}
}
Then in your controller you can call:
let inventoryView = InventoryView()
inventoryView.inventory = myPlayer.inventory
You cannot use a view in two places, at least not within the UI. Every view can be added to only one super view at a time.
If you need the same contents to be displayed twice, create a UIViewController class which's view contains the common UI, create two of those and add them to your UI.