viewwillappear

问题 I'm trying to figure out from Apple's sketchy documentation which method is the best place to be initializing and adding my Views controls to the controller's view. With winforms it's fairly straightforward, as they're always initialized inside InitializeDesigner , called in the constructor. I'm trying to match the reliability of this pattern if possible. I'm working with UIViewControllers and UITableViewControllers inside a UINavigationController most of the time - if this effects it all.

问题 I have an UIViewController having this method: - (void)viewWillDisappear:(BOOL)animated { [super viewWillDisappear:animated]; NSLog(@"DISAPPEAR"); lastKnownOrientation = [self interfaceOrientation]; } -(void)openSendVC{ SendMsgViewController *vc = [[SendMsgViewController alloc]initWithNibName:@"SendMsgViewController" bundle:nil]; [self.navigationController pushViewController:vc animated:NO]; } In the second view controller ( SendMsgViewController ) viewDidLoad I have the following: [self

问题 I'm writing an app and I need to change the view if the user is looking at the app while talking on the phone. I've implemented the following method: - (void)viewWillAppear:(BOOL)animated { [super viewWillAppear:animated]; NSLog(@"viewWillAppear:"); _sv.frame = CGRectMake(0.0, 0.0, 320.0, self.view.bounds.size.height); } But it's not being called when the app returns to the foreground. I know that I can implement: [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector

问题 In an application having UITabBarController , I want to implement following scenario: When user is on 'X' Tab , he/she does something & then move to another tabs. And again he/she comes back to 'X' tab( say after 5minutes-> this is important as I may change 5min to 10min in future ), then I want to show some message like your 'Session is expired'. Whenever user comes back 'X' Tab, it need to make server request to get response code. Depending upon that I want to show the pop-up 'Session is

问题 Due to the keywords "did" and "will" in UIViewController, I have am unsure where to put the code before/after calling super in viewDidLoad and viewWillAppear, in order to make the code run effectively. For example: - (void)viewDidLoad { [super viewDidLoad]; // Code is here because whatever // setup in super should been done first // before we can do anything } - (void)viewWillAppear:(BOOL)animated { // Code should be here to finish // whatever we want to do in our view // before calling super

问题 I have a UIViewController that I am loading from inside another view controller and then adding its view to a UIScrollView . self.statisticsController = [self.storyboard instantiateViewControllerWithIdentifier:@"StatisticsViewController"]; self.statisticsController.match = self.match; [self.scrollView addSubview:self.statisticsController.view]; I've put breakpoints in the statistics view controller and viewDidLoad is being called but viewWillAppear isn't. Is it because I'm not pushing it onto

问题 I am battling with this piece of code for days now, I really would appreciate your insight. So here it is... fileName which is declared in my .h file as NSString *fileName; and later as @property (nonatomic, copy) NSString *fileName; is not accessible inside viewWillDisappear . It just shows up as nil object, or some weird value when I debug. When I debug, my console show this msg: Printing description of fileName: FileNumber1 When I reach to viewWillDisappear my console shows this: Printing

问题 I have a button that pushes to a settings viewController . On that settings viewController I has a switch to invert all the colors on the original view, an inversion which I've done programmatically. I made inverted button images to replace the original images. When I return to the original view, I have viewWillAppear call the method to invert if the switch has been flipped. Everything changes accordingly except for two disabled buttons. The switch value is saved under the default settings so

问题 I have an application which has more than one view. When I return to the foreground from the background, I want to determine which view I am in presently. How would I do that? [EDIT] I understand visibleViewController property of navigationController might help. But, I want to know how to use the pointer returned by it in my comparison with a UIViewController object. How can we compare pointers? Some code snippets would be very helpful. 回答1: zirinisp's Answer in Swift: extension UIWindow {

问题 I'm writing my own SplitViewController from scratch (i.e. by subclassing UIViewController and not UISplitViewController ). It has two sub-viewControllers (one for the left panel and one for the detail right panel), to which I need to send the appropriate messages ( viewWillAppear, viewDidAppear, viewWillDisapppear and viewDidDisappear ). I am already forwarding those messages when my custom SplitViewController receives them and it works fine. However I am struggling to figure out when to send