How did you reinstall ? Did you reload from Mac Appstore ? Maybe trying to use an older version of XCode could help ? https://stackoverflow.com/questions/59856774/mac-os-catalina-gfortran-ld-library-not-found-for-lgcrt1-o

Conditions for applying are given here: https://developer.apple.com/wwdc21/swift-student-challenge/ Applying Build your Swift playground, answer a few written prompts, provide documentation, and submit. To be eligible for the Challenge, you must: Be 13 years of age or older, or the equivalent minimum age in the relevant jurisdiction (for example, 16 years of age in the European Union); Be registered for free with Apple as an Apple developer or be a member of the Apple Developer Program; and Fulfill one of the following requirements: Be enrolled in an accredited academic institution or official homeschool equivalent; Be enrolled in a STEM organization’s educational curriculum; Be enrolled in an Apple Developer Academy; or Have graduated from high school or equivalent within the past 6 months and be awaiting acceptance or have received acceptance to an accredited academic institution. See last condition: Have graduated from high school or equivalent within the past 6 months and be awaiting acceptance or have received acceptance to an accredited academic institution. So, july 2020 graduation does not match. But may be you meet one of the other requirements ?

Unless I miss something, you want to authorise change only within the same section. So, you should change line 6 as: if (sourceSection == destSection) { With your code, you could move from section 0 to section 1. In the else { }, you could just emit a beep, to let user know something wrong occurred. Or even better, create a counter of mismoves: var counter = 0 In else, increment counter and trigger alert only if count is 3 } else { count += 1 if count = 3 { // display alert count = 0 // Then reset count to 0 } else { // play a beep } } If that solves the problem, don't forget to close the thread by marking correct answer. Otherwise, please give details on errors: I am using following code but It is giving me errors...

Does it work for iOS 13 or higher ? Please post the exact complete error message.

Could you try to isolate the problem ? What happens when: you comment out lines 6 to 11 and another try: not using beginUpdates (comment out lines 13 and 15) BTW, doc recommends to preferably use  performBatchUpdates(:completion:) method instead (of beginUpdates-endUpdates): Use the performBatchUpdates(:completion:) method instead of this one whenever possible.  (void)insertRow { NSUInteger rowIndex = self.items.count == 0 ? 0 : 1; [self.items insertObject:[NSString stringWithFormat:@"New item %lu", self.items.count + 1] atIndex:rowIndex]; [UIView beginAnimations:@"twisterTableAnimationId" context:nil]; [UIView setAnimationDuration:1.0f]; [CATransaction begin]; [CATransaction setCompletionBlock:^{ NSLog(@"animation complete"); }]; [self.tableView beginUpdates]; [self.tableView insertRowsAtIndexPaths:@[[NSIndexPath indexPathForRow:rowIndex inSection:0]] withRowAnimation:UITableViewRowAnimationNone]; [self.tableView endUpdates]; [CATransaction commit]; [UIView commitAnimations]; CGRect frame = self.tableView.frame; frame.size.height = [self.tableView sizeThatFits:CGSizeMake(frame.size.width, CGFLOAT_MAX)].height; self.preferredContentSize = frame.size; }

You should be able to download, but you must check you have enough memory available. You could also first try to reboot the iPhone. See here for other possible reasons: https ://www.businessinsider.c om/why-wont-my-iphone-update-to-ios-13?IR=T#ensure-you-have-enough-available-storage-3

You have several threads opened. Don't forget to close them once solved.

You may have to maintain a reference to this window, through environment object. Have a look here: https://stackoverflow.com/questions/60359808/how-to-access-own-window-within-swiftui-view

When you tried: self.view.window.windowScene Which object is self ?

Could you print the values of self.sceneView.center.x, self.sceneView.center.y ?

I would really be surprised those elements are considered public domain by Marvel. Anyway, to pass the app review, you should need a formal acceptance from Marvel. Honestly I do doubt you will ever get it.

You cannot change a button behaviour. That's forbidden. But to control brightness:         UIScreen.main.brightness = 0.1 // between 0 and 1

You may officially ask Marvel. But even for the challenge, I doubt Apple would prime an app that has any possible copyright issue. Good luck, and don't forget to close the the thread.

Could you show some code ? Are you sure you do not recreate a new label in header and foyer ? If so, a way to solve would be to check if supplementary view already exist before creating, or delete them before recreating. If that's OK, don't forget to close the thread (and also close other threads you have opened).

Here is the problem: line 8 you recreate a label and add it over if there is already an existing one: let headerUILabelText = UILabel() headerUILabelText.textAlignment = .left headerUILabelText.font = UIFont.systemFont(ofSize: 20, weight: .bold) headerUILabelText.numberOfLines = 0 headerUILabelText.text = "Your Roll Number is \(NumberInteger). Your Exam Numbers are \(examNumbers(number: "\(NumberInteger)"))" headerUILabelText.textColor = .darkGray headerUILabelText.lineBreakMode = .byTruncatingTail headerView.addSubview(headerUILabelText) You should either: remove subviews first test if there is already a UILabel and not recreate if so replace existing subview. I have used this extension: extension UIView { class func getAllSubviewsT: UIView(from parentView: UIView) - [T] { return parentView.subviews.flatMap { subView - [T] in var result = getAllSubviews(from: subView) as [T] if let view = subView as? T { result.append(view) } return result } } class func getAllSubviews(from parentView: UIView, types: [UIView.Type]) - [UIView] { return parentView.subviews.flatMap { subView - [UIView] in var result = getAllSubviews(from: subView) as [UIView] for type in types { if subView.classForCoder == type { result.append(subView) return result } } return result } } func getAllSubviewsT: UIView() - [T] { return UIView.getAllSubviews(from: self) as [T] } func getT: UIView(all type: T.Type) - [T] { return UIView.getAllSubviews(from: self) as [T] } func get(all type: UIView.Type) - [UIView] { return UIView.getAllSubviews(from: self) } } And call in your case: let allLabels = self.headerView.get(all: UILabel.self) for sub in allLabels { sub.removeFromSuperview() } And now you can safely add subview: headerView.addSubview(headerUILabelText)