Xcode application delegate

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What does the AppDelegate class do?

Hello, looking for a answer to a simple problem. I recieve a notification in my IOS app delegate and need to pass that data on to a my main view controller for displaying. In many cases, the view controller you're looking for is a singleton only one of them exists for the entire lifetime of your appor at least only one of them exists at any one time. You can set the property in the view controller's viewDidLoad, and clear it if necessary in deinit, but the property needs to be weak in that case, otherwise it creates a retain cycle. Or you can set it in viewWillAppear and clear it in viewDidDisappear. Another approach is to walk your controller containment hierarchy, starting with the main UIWindow's rootViewController which may actually be the view controller you want. Most app templates provide a property in the app delegate that's automatically set to the UIWindow. This approach works fine so long as your view controller is on the device's main screen and not on an external display, which has a different UIWindow. Your view controller can then observe that notification. Error: You don't have JavaScript enabled. This tool uses JavaScript and much of it will not work correctly without it enabled. Please turn JavaScript back on and reload this page. Please enter a title. You can not post a blank message. Please type your message and try again. This seems to be a popular question on the internet, but not finding any working answers. What is best pratice? Thank you! This content has been marked as final. Show 2 replies.

iOS - Delegates

A dictionary indicating the reason the app was launched if any. The contents of this dictionary may be empty in situations where the user launched the app directly. For information about the possible keys in this dictionary and how to handle them, see Launch Options Keys. The return value is ignored if the app is launched as a result of a remote notification. This method represents your last chance to process any keys in the launch Options dictionary. That notification is sent shortly after this method returns. If either method returns falsethe URL is not handled. If you do not implement one of the methods, only the return value of the implemented method is considered. Tells the delegate that the launch process has begun but that state restoration has not yet occurred. Keys used to access values in the launch options dictionary passed to your app at initialization time. Tells the delegate when the app has finished launching. Language: Swift Objective-C. Tells the delegate that the launch process is almost done and the app is almost ready to run. SDKs iOS 3. Framework UIKit. Launch Options Key : Any]? See Also Initializing the App. Launch Options Key Keys used to access values in the launch options dictionary passed to your app at initialization time. Name Posted immediately after the app finishes launching. Related Documentation.

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By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I have just been learning iPhone apps development but I have a hard time in understanding what delegate actually means? Can anyone tell me with example what it does and how important it is? Thanks for any helps! It's a key concept to understand conceptually so getting your head around how to think about it ahead of the technical details is important. Simply put, a delegate is a callback. Examples: UITableView - a table view is just a control that knows how to render a list of cells. It handles all the heavy lifting of rendering, scrolling, etc But, it has no idea how to load your data. So you implement a datasource delegate which has methods to get the cell data for a given row etc That makes it easy on you. You just use the control and plug in the specifics for your data. The UITableView will do everything for you A delegate answers those few specific questions. A text control - you add a text control to your view and voila! But what if you want to do something when they start typing or when they're done typing? Well, the text control offers a delegate with methods that allow you to hook into the execution pipeline of the text control. It allows the text control to do everything for you and allows you to interject code where you need it. Many times, there's way to interject code to make a decision on whether something is allowed. The control will call back and ask, should I be able to do x? You can interject code and influence the behavior. If you're creating a control or class, you can create your own protocol, datasource delegates etc For example, let's say you wanted to create a task control. You could:.

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The app delegate is effectively the root object of your app, and it works in conjunction with UIApplication to manage some interactions with the system. Responding to notifications originating from outside the app, such as low-memory warnings, download completion notifications, and more. For more information about how you use the app delegate object to initialize your app at launch time, see Responding to the Launch of Your App. In iOS 12 and earlier, you use your app delegate to manage major life cycle events in your app. Specifically, you use methods of the app delegate to update the state of your app when it enters the foreground or moves to the background. Tells the delegate that the launch process has begun but that state restoration has not yet occurred. Keys used to access values in the launch options dictionary passed to your app at initialization time. Tells the delegate when the app has finished launching. Tells the delegate that the user closed one or more of the app's scenes from the app switcher. Posted when there is a significant change in time, for example, change to a new day midnightcarrier time update, and change to or from daylight savings time. Tells your delegate to save any high-level state information at the beginning of the state preservation process. Tells your delegate to restore any high-level state information as part of the state restoration process. Sent to the delegate when Apple Push Notification service cannot successfully complete the registration process. Tells the delegate if your app takes responsibility for notifying users when a continuation activity takes longer than expected. Asks the delegate to open a resource specified by a URL, and provides a dictionary of launch options. Asks the delegate to grant permission to use app extensions that are based on a specified extension point identifier. Asks the delegate for the interface orientations to use for the view controllers in the specified window. This exception is thrown if a view controller or the app returns 0 instead of a valid set of supported interface orientation values. Called when your app has been activated because user selected a custom action from the alert panel of a local notification. Called when your app has been activated by the user selecting an action from a local notification. Called when your app has been activated by the user selecting an action from a remote notification. Respond to system notifications when your app is in the foreground or background, and handle other significant system-related events. Language: Swift Objective-C. Protocol UIApplication Delegate. A set of methods that you use to manage shared behaviors for your app. SDKs iOS 2.

Understanding the iOS 13 Scene Delegate

I've read in several places that the default coredata code produce by xcode, when creating a new project, shouldn't really be in the app delegate file. I'm new to core data and am finding it difficult to make sense of the many contradictory examples I'm finding on the Internet. In some cases, admittedly they are just examples, the data manipulation and retrieval code is also in the app delegate. I ask because I shifted the default persistent container and context etc. Foolishly I thought I'd do my learning by building what I thought, based on many years experience with VB etc. Turns out that nothing is that simple. I've hit so many walls I think that my approach in many places is fundamentally wrong. I don't learn well reading manuals, rather I prefer working examples etc. If anyone has an example of, or a link to, code that demonstrates correctly how to work with core data with relationships etc. Contradictory examples exist on the Internet because there are a variety of different ways to structure code, and the ultimate rule is "Does this code work? Counter points: Once upon a time, the first thing in the Core Data programming guide was essentially "Put this manual down and don't come back until you're familiar with threading, the object model, and other related mechanisms. Go work on sample projects that don't use Core Data; then come back when you're ready. That doesn't appear to be the right question. If you're getting an error stating that an array is being mutated while being iterated, that's a problem with your code where you need to make a copy of the array before you iterate it. If you don't understand what's mutating the array, that's a more important point to investigate. Where a managed object context comes from is entirely application-dependent. In a Cocoa document-based application using NSPersistentDocument, the persistent document typically creates the context and gives you access to it through the managedObjectContext method. In a single-window application, if you create your project using the standard project assistant, the application delegate the instance of the NSApplicationDelegate class again creates the context and gives you access to it through the managedObjectContext method. In this case, however, the code to create the context and the rest of the Core Data stack is explicit. It is written for you automatically as part of the template. Do not use instances of subclasses of NSController directly to execute fetches. For example, do not create an instance of NSArrayController specifically to execute a fetch. Controllers are for managing the interaction between your model objects and your application interface. At the model object level, use a managed object context to perform the fetches directly. Keep in mind that CD assumes a specific basket of pre-existing skill sets. Your approach is only wrong in that context and how you measure up. Attempting CD without them puts you on a playing field without knowing what the game is, much less understanding how to play it. Nothing like a stretch goal to drive learning, but keep your expectations in line with this one. There may simply be more walls than you anticipated, so dress accordingly. And don't get me started on VB Word from the 23rd century is it and disco still s u c k.

14 IOS AppDelegate Lifecycle -

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