What would be the simplest way to convert an existing application with xib files based on UIWindow into a self contained view controller?
Editing post to address comment from OP:
In future apps, you should avoid acting directly upon a UIWindow whenever possible. However, now that you are stuck with an App A that directly acts upon the window, I would suggest that instead of doing a bunch of work to make your app properly use a UIViewController, you can just make App B into an app that uses two windows:
When App B wants to show the content of App A, just instantiate a new UIWindow windowOfAppA, set its rootViewController to the rootViewController of App A, and then call '[windowOfAppA makeKeyAndVisible];'. Once App A is done doing it's work, it can resign key window status by calling '[windowOfAppB makeKeyAndVisible];'.
Again, I emphasize that the technique I am grudgingly describing is terrible style and in the future your apps should only use one window it should only act upon it when absolutely necessary. Whenever possible, do all your work through view controllers.
Previous content of this answer:
What is your ultimate goal? Are you
trying to turn App A into a part of
App B? If so, you don't have to make
any changes to your existing class
hierarchy or nib files. All you have
to do is copy all of the files from
App A to App B and instantiate App A's
root view controller from within App B
(perhaps using
presentModalViewController:animated:)
and everything should work great.
Related
In my SwiftUI project I see AppDelegate file as well as a SceneDelegate file.
What are the differences between them?
For example between the methods in SceneDelegate
scene(_:willConnectTo:options:)
and in the AppDelegate
application(_:didFinishLaunchingWithOptions:)
The two files are meant to split the work by what is needed to run the app as a whole and what is needed for one "instance" that would support visibly running in the background. This would be something like configuring a database once, but displaying different sets of values by window.
You could think of them as the global and private versions. One is shared and the other is limited to the individual owner. In a way, they are exactly what you would expect by the names.
Multi-window support is happening
Next time you create a new Xcode project you’ll see your AppDelegate
has split in two: AppDelegate.swift and SceneDelegate.swift. This is a
result of the new multi-window support that landed with iPadOS, and
effectively splits the work of the app delegate in two.
From iOS 13 onwards, your app delegate should:
Set up any data that you need for the duration of the app.
Respond to any events that focus on the app, such as a file being shared with you.
Register for external services, such as push notifications.
Configure your initial scenes.
In contrast, scene delegates are there to handle one instance of your
app’s user interface. So, if the user has created two windows showing
your app, you have two scenes, both backed by the same app delegate.
Keep in mind that these scenes are designed to work independently from
each other. So, your application no longer moves to the background,
but instead individual scenes do – the user might move one to the
background while keeping another open.
Courtesy of https://www.hackingwithswift.com/articles/193/whats-new-in-ios-13
AppDelegate is responsible for handling application-level events(like app launch), application lifecycle, and setup.
SceneDelegate is responsible for handling what is shown on the screen (Windows or Scenes) and managing the way your app is shown.
scene(_:willConnectTo:options:) is the first method called in UISceneSession life cycle. This method will create a new UIWindow, set the root view controller, and make this window the key window to be displayed.
application(_:didFinishLaunchingWithOptions:) is called when the application is launched and where the application set-up is done. Earlier iOS 13, we might have used this method to configure the UIWindow object and assign a ViewController instance to the UIWindow object to make it display on the screen. From iOS 13, if your application has scenes, then AppDelegate is no longer responsible for handling this and is moved to SceneDelegate.
From: https://medium.com/#kalyan.parise/understanding-scene-delegate-app-delegate-7503d48c5445
Multiplatform
In addition to the answer of Abandoned Cart, Since Xcode 11, You have a new option called Multiplatform for choosing as a starting template. That's where you will only see a file contains:
#main
struct MyMultiplatformApp: App {
var body: some Scene {
WindowGroup {
ContentView()
}
}
}
This is how the system knows where to start the code with #main (in Swift 5.3) and it contains WindowGroup that manages multiple windows of your app in all apple platforms. So you don't need the be worry about SceneDelegate and AppDelegate anymore.
If you need it to be like the old app delegate, for example when you want to use its methods, You should subscribe for corresponding notifications or use the UIAppDelegateAdapter wrapper as I described here
I created a new project "Single View Application" and designed the mainView with Storyboard. My main view contains a UIButton that opens the camera, the camera scans barcode and automatically goes to a website. Now I created a webView programmatically so that website can open and also created a UIButton inside the webView. Now I want that UIButton to act as home botton and return to mainview. I am unable to do that, please help.
ViewController.m code: http://cl.ly/FKj8
My storyboard looks like:
You really should look into the View Controller Programming Guide -- by switching around the contents of a single view controller, you're making a lot of extra work for yourself with little benefit. By using multiple view controllers when you want to have different "screens" in your app, you can take advantage of storyboarding for easier development, and you automatically get better memory management (read: less potential for crashes), too.
However, to more directly answer your question... if you're putting the WebView into the view hierarchy with [self.view addSubview:webView], you can remove it with [webView removeFromSuperview]. (This means you'll have to keep a reference to the WebView around so you can refer to it when you want to dismiss it.)
I also noticed in the code you posted to cl.ly an unrelated method -deviceModel which uses uname() to get device information. This is a bad idea, for two reasons:
uname() isn't guaranteed to do something useful on an iOS device (even if it currently does). Use the UIDevice class instead if you need this kind of info, or...
Generally, you don't want to test for the device name to enable functionality in your app; instead, you should test for the capabilities you need. (For example, if you look for a device name starting with "iPhone 4" to test for a Retina display, you'll miss the 4th-generation iPod touch, and the iPhone-5-or-whatever-they-call-what's-next. Instead, use the UIScreen class.)
I was using Xcode 4.1 and after upgrading to 4.2, things started to become out of date. I am using many examples from different books, such as Big Nerd Ranch Guides, which do not use Storyboards and the Windows-Based Application had been changed to "Empty" Application.
With these new changes, I feel like the books and tutorials I had been using to start have become outdated. In many of these examples, they say to write the methods and variables in the delegate header files for 4.1. With the new 4.2 Xcode, there is an AppDelegate and ViewController. Should I still be writing the methods and class members in the AppDelegate, or should I be now writing them in the Controller file?
I am confused. Does Apple now want us to create our controller and reference it through the delegate?
When your app is run, it creates an instance of UIApplication. You want to know things that only the UIApplication object knows (did we just get switched to the background? did we just open?) so you use the delegate pattern to get it. When you start a new project Apple starts you off with an already-assigned App Delegate. You can open up MainWindow.nib and inspect your App Delegate to see how it is connected to your UIApplication instance (File's Owner, in this case).
In general you only want to put code in there that has to do with the basic functionality of your app. Launch, quit, go to background and come to foreground are when you'll be doing things in the App Delegate.
Most everything else should go in your view controllers or model objects. Since 'delegate' is just a design pattern, your view controllers can be delegates of other objects. For example, if you present a UITableView, you will assign a view controller as it's delegate in order to respond to events such as selection and scrolling. Your app has many delegates, but it only has one App Delegate.
The AppDelegate is really just a "launcher" for your app. Ie: You shouldn't be writing much code in it at all.
If you're concerned with "set up" code, do it in your View Controller, under viewDidLoad.
Now,I gonna Develop an App ,which wants to switch from many different Views irregularly,also the views need to load large resources,AKA,it's hard to manage memory.Are there any good solustion?
PS：I created a ViewController as RootViewController,and When a button was Touch,run the code as
"ViewController=newController"
.The problem came,The new View loaded wrong way,it rotate so that couldn't show in a correct way.
I google for the solution,some one said ,I should replace the rootViewController,just like that,
[UIApplication sharedApplication].delegate.window.rootViewController=newController;
But I can't get/set the rootViewController in other class though it's a singleton.
Why not having a class that handles all the view switches ?
This article describes an architecture that might be helpfull: http://www.mikeziray.com/2010/01/27/handling-your-initial-view-controllers-for-iphone/comment-page-1/#comment-607
Could anyone tell me when we use the AppDelegate.m and AppDelegate.h during iPhone programming? I have used only the ViewController.m and ViewController.h for basic learning. I just want to know when and why AppDelegate is used.
Both define classes, but the classes are used for different things. ViewController.h/m define a view controller class that manages a hierarchy of views -- basically, one screen of an application. You might have multiple screens that each have their own view controller.
AppDelegate.h/m define a class that manages the application overall. The app will create one instance of that class and send that object messages that let the delegate influence the app's behavior at well-defined times. For example, -application:didFinishLaunchingWithOptions: is sent when the app has finished launching and is ready to do something interesting. Take a look at the UIApplicationDelegate reference page for a list of messages that the app delegate can implement to modify the behavior of the application.
I would like to add the following to #Caleb's answer.
If care is not taken, the AppDelegate could easily become one of the most accessed objects in the application. I usually refrain from calling methods in the AppDelegate from any of my ViewControllers. Unless, something needs to be reported to the AppDelegate that would influence the behaviour of the whole application.
I keep my AppDelegate for the following:
initialization: whatever needs to be done on the very first launch (after an install or an update)
data migration from version to version (e.g. if you use CoreData and migrations)
configuration of objects linked via IBOutlets from MainWindow.xib
determining the initial orientation to launch in
saving uncommitted data / state prior to the application being terminated or entering background mode
registering for the Apple Push Notification Service and sending the device token to our server
opening one of the supported application URLs (e.g. maps://)
For other use case scenarios and a more thourough description of the AppDelegate, see the iOS Application Programming Guide.
The view-controller. h/m is responsible of controlling the connection between your model and your view (more on MVC here).
AppDelegate. h/m is responsible for the life-cycle of your application. What to do when the user press the home button and exit your app, what to do when the app enter background. Things like this.