Presenting a UIAlertController once you’re not straight inside a position controller tin beryllium a difficult occupation that galore iOS builders brush. It’s a communal script, peculiarly once running with app extensions, inheritance duties, oregon definite architectural patterns. This seemingly elemental project tin go a origin of vexation if you’re not acquainted with the accurate attack. Successful this article, we’ll dive heavy into the intricacies of presenting alerts extracurricular of a position controller discourse, exploring assorted options, champion practices, and possible pitfalls.
Knowing the Situation
UIAlertController, the modular manner to immediate alerts and act sheets successful iOS, is designed to beryllium offered by a position controller. Its position depends connected the position controller’s position hierarchy. Once you’re extracurricular this hierarchy, specified arsenic successful an app delay oregon a inheritance project, trying to immediate an alert straight tin pb to crashes oregon sudden behaviour.
The center content stems from the information that immediate(_:animated:completion:), the methodology utilized to show a UIAlertController, requires a presenting position controller. With out 1, the scheme doesn’t cognize wherever to anchor the alert successful the UI.
The cardinal is to discovery the topmost introduced position controller and usage that arsenic the presenter for your alert.
Uncovering the Topmost Position Controller
The resolution entails traversing the exertion’s framework hierarchy to find the topmost introduced position controller. This is usually the position controller presently available to the person.
Presentβs a Swift relation to accomplish this:
func topMostViewController() -> UIViewController? { defender fto windowScene = UIApplication.shared.connectedScenes.archetypal arsenic? UIWindowScene, fto framework = windowScene.home windows.archetypal(wherever: { $zero.isKeyWindow }) other { instrument nil } var topController = framework.rootViewController piece fto presentedViewController = topController?.presentedViewController { topController = presentedViewController } instrument topController }
This relation iterates done the offered position controllers till it finds the 1 astatine the apical of the hierarchy. This ensures that your alert is offered connected the presently progressive surface.
Presenting the Alert
Erstwhile you’ve obtained the topmost position controller, presenting the UIAlertController turns into easy:
if fto topVC = topMostViewController() { fto alert = UIAlertController(rubric: "Alert Rubric", communication: "Alert Communication", preferredStyle: .alert) alert.addAction(UIAlertAction(rubric: "Fine", kind: .default, handler: nil)) topVC.immediate(alert, animated: actual, completion: nil) }
This codification snippet demonstrates however to immediate a elemental alert. Retrieve to accommodate the rubric, communication, and actions to your circumstantial wants. This technique ensures your alert shows accurately, equal extracurricular a emblematic position controller discourse.
Dealing with Border Instances
Piece the supra attack plant successful about circumstances, definite conditions necessitate further information.
App Extensions
Successful app extensions, accessing the exertion’s chief framework straight is not permitted. Alternatively, you demand to usage the delay discourse’s immediate(_:animated:completion:) technique, offering a position controller inside the delay arsenic the presenter. Frequently, this means creating a impermanent oregon devoted position controller inside the delay solely for presenting alerts.
Inheritance Duties
Presenting UI parts from inheritance duties is mostly discouraged. If perfectly essential, guarantee you dispatch the alert position backmost to the chief thread utilizing DispatchQueue.chief.async.
- Ever dispatch UI updates to the chief thread.
- Debar presenting UI from inheritance duties if imaginable.
Champion Practices
Pursuing these champion practices ensures a creaseless and dependable alert position education.
- Encapsulate the logic: Make a reusable inferior relation to grip uncovering the topmost position controller and presenting the alert. This promotes codification cleanliness and reduces redundancy.
- Grip nil topmost position controller: The
topMostViewController()relation mightiness instrumentnilnether circumstantial circumstances. Instrumentality due mistake dealing with to forestall crashes. See logging the case oregon offering fallback behaviour. - Contextualize your alerts: Trade broad and concise alert messages that supply discourse to the person. Debar generic messages that message small worth.
For additional accusation, mention to Pome’s authoritative documentation connected UIAlertController.
Infographic Placeholder: [Insert infographic illustrating the position controller hierarchy and the procedure of uncovering the topmost position controller]
Options to UIAlertController
Piece UIAlertController is the modular attack, another strategies be for displaying accusation to the person, particularly successful constrained environments similar app extensions. See utilizing section notifications oregon, if due, updating the UI of your containing app straight (if relevant) arsenic options.
Research 3rd-organization libraries for personalized alert displays that message much flexibility successful status of quality and behaviour. Nevertheless, cautiously measure immoderate 3rd-organization room to guarantee it aligns with your taskβs necessities and maintains the integrity of your app’s show.
Seat besides this adjuvant assets connected Stack Overflow.
- See person education once selecting alternate position strategies.
- Totally trial immoderate alternate options to guarantee compatibility and performance.
This article offers you with the instruments and strategies to efficaciously immediate UIAlertController situations once you aren’t running straight inside a position controller. Retrieve to grip border circumstances and travel champion practices to guarantee a polished and person-affable education. By knowing the underlying rules and making use of the offered options, you tin flooded this communal situation and present a seamless person education. Larn much astir precocious iOS improvement strategies present. Dive into the codification examples and accommodate them to your circumstantial usage instances. You tin discovery much utile ideas and tips connected iOS improvement and Swift programming.
FAQ
Q: What if the topMostViewController() relation inactive returns nil?
A: This might bespeak an content with your app’s framework setup. Treble-cheque that the keyWindow place is accurately fit. Alternatively, if running successful a discourse wherever a framework isn’t readily disposable (similar any inheritance duties), you mightiness demand to re-measure the necessity of presenting a UI component and research alternate connection strategies.
Question & Answer :
Script: The person faucets connected a fastener connected a position controller. The position controller is the topmost (evidently) successful the navigation stack. The pat invokes a inferior people methodology referred to as connected different people. A atrocious happening occurs location and I privation to show an alert correct location earlier power returns to the position controller.
+ (void)myUtilityMethod { // bash material // thing atrocious occurred, show an alert. }
This was imaginable with UIAlertView (however possibly not rather appropriate).
Successful this lawsuit, however bash you immediate a UIAlertController, correct location successful myUtilityMethod?
Astatine WWDC, I stopped successful astatine 1 of the labs and requested an Pome Technologist this aforesaid motion: “What was the champion pattern for displaying a UIAlertController?” And helium stated they had been getting this motion a batch and we joked that they ought to person had a conference connected it. Helium stated that internally Pome is creating a UIWindow with a clear UIViewController and past presenting the UIAlertController connected it. Fundamentally what is successful Dylan Betterman’s reply.
However I didn’t privation to usage a subclass of UIAlertController due to the fact that that would necessitate maine altering my codification passim my app. Truthful with the aid of an related entity, I made a class connected UIAlertController that supplies a entertainment technique successful Nonsubjective-C.
Present is the applicable codification:
#import "UIAlertController+Framework.h" #import <objc/runtime.h> @interface UIAlertController (Framework) - (void)entertainment; - (void)entertainment:(BOOL)animated; @extremity @interface UIAlertController (Backstage) @place (nonatomic, beardown) UIWindow *alertWindow; @extremity @implementation UIAlertController (Backstage) @dynamic alertWindow; - (void)setAlertWindow:(UIWindow *)alertWindow { objc_setAssociatedObject(same, @selector(alertWindow), alertWindow, OBJC_ASSOCIATION_RETAIN_NONATOMIC); } - (UIWindow *)alertWindow { instrument objc_getAssociatedObject(same, @selector(alertWindow)); } @extremity @implementation UIAlertController (Framework) - (void)entertainment { [same entertainment:Sure]; } - (void)entertainment:(BOOL)animated { same.alertWindow = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds]; same.alertWindow.rootViewController = [[UIViewController alloc] init]; id<UIApplicationDelegate> delegate = [UIApplication sharedApplication].delegate; // Purposes that does not burden with UIMainStoryboardFile mightiness not person a framework place: if ([delegate respondsToSelector:@selector(framework)]) { // we inherit the chief framework's tintColor same.alertWindow.tintColor = delegate.framework.tintColor; } // framework flat is supra the apical framework (this makes the alert, if it's a expanse, entertainment complete the keyboard) UIWindow *topWindow = [UIApplication sharedApplication].home windows.lastObject; same.alertWindow.windowLevel = topWindow.windowLevel + 1; [same.alertWindow makeKeyAndVisible]; [same.alertWindow.rootViewController presentViewController:same animated:animated completion:nil]; } - (void)viewDidDisappear:(BOOL)animated { [ace viewDidDisappear:animated]; // precaution to guarantee framework will get destroyed same.alertWindow.hidden = Sure; same.alertWindow = nil; } @extremity
Present is a example utilization:
// demand section adaptable for TextField to forestall hold rhythm of Alert other UIWindow // would not vanish last the Alert was dismissed __block UITextField *localTextField; UIAlertController *alert = [UIAlertController alertControllerWithTitle:@"Planetary Alert" communication:@"Participate any matter" preferredStyle:UIAlertControllerStyleAlert]; [alert addAction:[UIAlertAction actionWithTitle:@"Fine" kind:UIAlertActionStyleDefault handler:^(UIAlertAction *act) { NSLog(@"bash thing with matter:%@", localTextField.matter); // bash NOT usage alert.textfields oregon other mention the alert successful the artifact. Volition origin hold rhythm }]]; [alert addTextFieldWithConfigurationHandler:^(UITextField *textField) { localTextField = textField; }]; [alert entertainment];
The UIWindow that is created volition beryllium destroyed once the UIAlertController is dealloced, since it is the lone entity that is retaining the UIWindow. However if you delegate the UIAlertController to a place oregon origin its hold number to addition by accessing the alert successful 1 of the act blocks, the UIWindow volition act connected surface, locking ahead your UI. Seat the example utilization codification supra to debar successful the lawsuit of needing to entree UITextField.
I made a GitHub repo with a trial task: FFGlobalAlertController
