viewdidload

问题 This question already has answers here : Difference between viewDidLoad and viewDidAppear (2 answers) Closed last year . Bottom line is, I've been working on an app, and it seems that if I place a UIAlert in viewDidLoad , it gets called twice (from a delegate method of UIImagePickerController ). If I put it in viewDidAppear , it gets called once. I've looked through documentation but it just confuses me. 回答1: A UIView object can get loaded into memory and released multiple times without ever

问题 Let's say I have my initial vc called VC1, then I have a second one called VC2. VC1 has a segue to VC2, on VC2 there is a button that will dismiss VC2 and then show VC1. Once VC1 loads I want to run a method but I can't do that in view did load so where can I do it? [VC1] -> [VC2] 回答1: You can use a delegate method to achieve this. In the method you call to dismiss VC2 call the delegate. You can implement this delegate in VC1. 回答2: You can also try Unwind Segue for dismissing the VC2 and call

问题 //Objects list //objects scroll UIScrollView *objects; objects=[[UIScrollView alloc]initWithFrame:CGRectMake(0,80,512,688)]; objects.showsVerticalScrollIndicator=YES; objects.scrollEnabled=YES; objects.userInteractionEnabled=YES; objects.backgroundColor = [UIColor clearColor]; [self.view addSubview:objects]; [objects setUserInteractionEnabled:YES]; [objects setCanCancelContentTouches:YES]; objects.contentSize = CGSizeMake(512,689); //divider UIButton *divider = [UIButton buttonWithType

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 am using [CLLocationManager locationServicesEnabled] function to get the status whether location service is enabled or not. I kept code in viewDidLoad method. if(![CLLocationManager locationServicesEnabled]) { NSLog(@"No"); } else { NSLog(@"Yes"); } When I am running this app first time it returns Yes . Why? It should return me No . This is the case when I did not select "Allow" or "Don't allow" options. Means I neither allow nor don't allow but in viewDidLoad I got Yes . Now I select "Don

问题 Does viewDidLoad get called when you're popping back to a UIView? 回答1: viewDidLoad gets called whenever loadView is called. loadView is called whenever the view is requested from a UIViewController and it is currently nil. If you pop to a UIViewController and the view property is nil, loadView and hence viewDidLoad will be called. The view could be nil if it was never loaded or if it was unloaded while another view controller was on screen. It might never have been loaded if several view

问题 If I have a class and initialize a variable like so: class TestClass: UIViewController { var thisInt: Int = 10 } is that any different than initializing like so: class TestClass: UIViewController { var thisInt: Int! override func viewDidLoad() { super.viewDidLoad() thisInt = 10 } } I suppose my main questions lie in when the global initialization takes place, and is there a time when one would get called more than the other would be called with normal iOS Programming (not doing anything

问题 It seems that I'm having a problem with repeatmodeone: it does not repeat the video. This is the code for the video I have in the implementation: - (void)viewDidLoad{ NSURL *url = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:@"Space Particle" ofType:@"mp4"]]; MPMoviePlayerViewController *playerController = [[MPMoviePlayerViewController alloc]initWithContentURL:url]; [self presentMoviePlayerViewControllerAnimated:playerController]; [playerController.moviePlayer prepareToPlay];

问题 I am trying to implement the imagepickercontroller inside a UITabBarController. So far, so good.... In my ViewController, where I initiate the imagePickerController and then place in my TabBarViewController tabbar array, I implemented the "loadview" method: - (void)loadView{ self.arController = [[IFAugmentRealityController alloc] initWithViewController:self]; [self showCamera]; [self initOverlayController]; self.picker.delegate = self; [self.view addSubview:self.picker.view]; } - (void

问题 I have two ViewControllers. When I press a button on the FirstViewController the SecondViewController shows up. When I press a button on the SecondViewController the FirstViewController shows up again. The problem is, that the View on the FirstViewController does not load again. The ViewDidLoad loop does not load again. I want to create a loop, which checks a variable every single time the FirstViewController shows up. 回答1: Put that code in viewDidAppear or viewWillAppear. 回答2: viewDidLoad is