I currently have a UIView that programmatically has an embedded QLPreviewController in it. I need to get rid of the default navigator bar that the QLPreviewController has when the document/url is loaded. Is there a way to do this?
Currently, I've tried subclassing QLPreviewController and in the viewDidAppear set self.navigationController!.navigationBarHidden = true. But this doesn't work.
Sorry if this is a dupe question - I've been looking online the last few days and couldn't find a concrete answer with iOS 8/9.
I Solve this problem by using addChildViewController
- (void)viewDidLoad {
[super viewDidLoad];
[self setupPreviewController];
}
- (void)setupPreviewController {
self.previewController = [[QLPreviewController alloc] init];
[self addChildViewController:self.previewController];
[self.view addSubview:self.previewController.view];
//do autolayout
[self.previewController.view mas_makeConstraints:^(MASConstraintMaker *make) {
make.top.left.right.bottom.equalTo(self.view);
}];
self.navigationController.navigationBarHidden = YES;
}
Same thing apply in viewWillAppear and in viewDidLoad methods
self.navigationController!.navigationBarHidden = true
i hope this will help
It does appear to be possible. After inspecting the view hierarchy at runtime I found that the nav bar you see is actually a subview of the View Controller's view. The code below will remove it; however, it will not stay gone and it does not appear that there is any sanctioned way to modify the UI elements of this class. Any modification of this class will be a fragile hack and I'd recommend finding something less locked down to customize.
class MyPreviewViewController: QLPreviewController {
override func viewWillLayoutSubviews() {
super.viewWillLayoutSubviews()
if let subviewsWithNav = self.view.subviews.first?.subviews {
for view in subviewsWithNav {
if let navbar = view as? UINavigationBar {
navbar.isHidden = true
}
}
}
}
}
This worked for me:
class CustomQLPreview: QLPreviewController {
...
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
navigationController?.setNavigationBarHidden(true, animated: false)
}
}
Related
I am looking to build a custom error message in the form of a UIView. I would like to use this UIView for each UIViewController within my app. Obviously I don't want to recreate it for each screen, so I am looking for the best solution to "share" it.
Would it be better to create it as a UIViewController and add it that way or is there a better approach?
UIView instances are meant to be used in only one place. They can only have one superview and thus cannot be used in several view hierarchies at the same time.
If you change the superview of a view, you will actually move the view.
There are two possibilities I think:
either you want to always have this error message on screen. In that case, you should probably create a dedicated UIViewController as you mentioned, and always display it on screen,
or you want to display different errors. In that way, it makes sense to create an instance of your UIView for every controller in which you display an error.
Yes, use a ViewController, it is better than a simple view. Your message could have actions like buttons.
To avoid too many code duplications, you may use a mixin :
protocol ErrorDisplay {
func display(_ error: Error)
}
extension ErrorDisplay where Self: UIViewController {
func display(_ error: Error) {
let viewController = ErrorViewController(error: error)
// You could also add it as a child view controller rather than presenting it,
// if you want to add its view in the current hierarchy
present(viewController, animated: true, completion: nil)
}
}
And implement the protocol in each view controller that wishes to display a error.
extension LoginViewController : ErrorDisplay {}
extension SettingsViewController : ErrorDisplay {}
...
If you want a view which is always present on screen at that time you can use window to display a view.
Window is Root of all view that displaying on screen, Window always present so once you add your view in window that will always be present in screen.
Just use below code to add view to window
let window = UIApplication.shared.keyWindow!
let v = UIView(frame: CGRect(x: window.frame.origin.x, y: window.frame.origin.y, width: window.frame.width, height: window.frame.height))
window.addSubview(v);
For this problem, I prefer you to create a UIView class and you can reuse it in your viewController. For doing this follow these steps,
1. Create a Xib of UIView and design it what ever you want.
2. Create a UIView class
3. Change the fileOwner of Your UIView XIB to the created UIView class
4. Create an Outlet of ContentView in YourView.h
#property (strong, nonatomic) IBOutlet UIView *contentView;
5. Add the following codes in YouView.m
-(instancetype)initWithCoder:(NSCoder *)aDecoder
{
self = [super initWithCoder:aDecoder];
if(self)
{
[self customInit];
}
return self;
}
-(instancetype)initWithFrame:(CGRect)frame
{
self = [super initWithFrame:frame];
if(self)
{
[self customInit];
}
return self;
}
-(void) customInit
{
[[NSBundle mainBundle]loadNibNamed:#"View" owner:self options:nil];
[self addSubview:self.contentView];
self.contentView.frame = self.bounds;
}
6. Use this UIView in your ViewController what ever you want.
YourView *YourViewObj = [[YourView alloc] initWithFrame:CGRectMake(0, 0, 100,100)];
[self.view addSubview:YourViewObj];
This is the code I am using to set the constraints in viewDidLoad:
if (self.presentingViewController?.isKindOfClass(GameViewController) != nil) {
print("huhu")
self.bottomViewToBottomConstraint.constant = -367
self.bottomViewToHiddenButtonConstraint.constant = 401
} else {
self.bottomViewToBottomConstraint.constant = -200
self.bottomViewToHiddenButtonConstraint.constant = 200
print("No presenting viewController")
}
The message I'm getting is No presenting viewController. As you can see I am also setting constraints which will be animated differently, depending on what class is presenting viewController. So at what time it is already known who is presenting view controller and is also the right time to set the constraints? Thanks for help
As simple as:
After you add the bottomView to it's superview.
Try viewWillAppear method:
-(void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
// here
}
I'm trying to make a AVPlayerViewController go to full screen mode programmatically, coming from "embedded" mode, however this does not appear to be possible with the published API.
Is there a workaround that I'm missing? I'm interested in obtaining the same animation to the one that you get when the user presses the full screen button on the bottom right of the controls.
Using MPMoviePlayerController is not a viable alternative since I might have more than one video playing at a time.
Thanks.
AVPlayerViewController is a subclass of UIViewController, so it is presentable like any other view controller subclass. Are you able to use presentViewController:animated:completion?
self.avPlayerController.modalPresentationStyle = UIModalPresentationOverFullScreen;
[self presentViewController:self.avPlayerController animated:YES completion:nil];
This then shows the "Done" button in the top left-hand corner.
Updated for iOS 11
There is no supported way to programmatically go fullscreen with AVPlayerViewController (a bit of an oversight in my opinion).
However, AVPlayerViewController does contain a private method that does exactly that. You'll have to decide for yourself whether you'd want to use it or not given you're not supposed to call private methods.
AVPlayerViewController+Fullscreen.h
#import <AVKit/AVKit.h>
#interface AVPlayerViewController (Fullscreen)
-(void)goFullscreen;
#end
AVPlayerViewController+Fullscreen.m
#import "AVPlayerViewController+Fullscreen.h"
#implementation AVPlayerViewController (Fullscreen)
-(void)goFullscreen {
NSString *selectorForFullscreen = #"transitionToFullScreenViewControllerAnimated:completionHandler:";
if (#available(iOS 11.3, *)) {
selectorForFullscreen = #"transitionToFullScreenAnimated:interactive:completionHandler:";
} else if (#available(iOS 11.0, *)) {
selectorForFullscreen = #"transitionToFullScreenAnimated:completionHandler:";
}
SEL fsSelector = NSSelectorFromString([#"_" stringByAppendingString:selectorForFullscreen]);
if ([self respondsToSelector:fsSelector]) {
NSInvocation *inv = [NSInvocation invocationWithMethodSignature:[self methodSignatureForSelector:fsSelector]];
[inv setSelector:fsSelector];
[inv setTarget:self];
NSInteger index = 2; //arguments 0 and 1 are self and _cmd respectively, automatically set
BOOL animated = YES;
[inv setArgument:&(animated) atIndex:index];
index++;
if (#available(iOS 11.3, *)) {
BOOL interactive = YES;
[inv setArgument:&(interactive) atIndex:index]; //arguments 0 and 1 are self and _cmd respectively, automatically set by NSInvocation
index++;
}
id completionBlock = nil;
[inv setArgument:&(completionBlock) atIndex:index];
[inv invoke];
}
}
#end
UPDATE: Swift 4 version of ToddH's answer:
private func enterFullscreen(playerViewController: AVPlayerViewController) {
let selectorName: String = {
if #available(iOS 11.3, *) {
return "_transitionToFullScreenAnimated:interactive:completionHandler:"
} else if #available(iOS 11, *) {
return "_transitionToFullScreenAnimated:completionHandler:"
} else {
return "_transitionToFullScreenViewControllerAnimated:completionHandler:"
}
}()
let selectorToForceFullScreenMode = NSSelectorFromString(selectorName)
if playerViewController.responds(to: selectorToForceFullScreenMode) {
playerViewController.perform(selectorToForceFullScreenMode, with: true, with: nil)
}
}
In iOS11 there are 2 new properties for AVPlayerViewController: entersFullScreenWhenPlaybackBegins and exitsFullScreenWhenPlaybackEnds. You can enable full screen mode right after playback begins and disable it when playback ends with these properties. If you need to enable fullscreen mode after some delay you can use private API methods as ToddH mentioned in his answer. However in iOS11 _transitionToFullScreenViewControllerAnimated:completionHandler: method is not available anymore, there is the same method called _transitionToFullScreenAnimated:completionHandler:. The second method accepts the same arguments as the first one.
I can show an example how to use it. First of all you need to create AVPlayerViewController instance in your UIViewController:
private let playerController : AVPlayerViewController = {
if let urlForPlayer = URL(string: "your_video_url") {
$0.player = AVPlayer(url: urlForPlayer)
}
return $0
} (AVPlayerViewController())
Then you need to setup view for AVPlayerViewController and add it to your current controller view. Function setupAVplayerController can do it for you:
private func setupAVplayerController() {
self.addChildViewController(self.playerController)
self.playerController.view.frame = CGRect(x: 0.0, y: 0.0, width: 200.0, height: 200.0)
self.view.addSubview(self.playerController.view)
self.playerController.didMove(toParentViewController: self)
}
Function enterFullscreen forces full screen mode for AVPlayerViewController:
private func enterFullscreen(playerViewController:AVPlayerViewController) {
let selectorName : String = {
if #available(iOS 11, *) {
return "_transitionToFullScreenAnimated:completionHandler:"
} else {
return "_transitionToFullScreenViewControllerAnimated:completionHandler:"
}
}()
let selectorToForceFullScreenMode = NSSelectorFromString(selectorName)
if playerViewController.responds(to: selectorToForceFullScreenMode) {
playerViewController.perform(selectorToForceFullScreenMode, with: true, with: nil)
}
}
And now you need to call all these functions where you need it, for example in viewDidAppear:
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
//Your code
self.setupAVplayerController()
self.playerController.player?.play()
DispatchQueue.main.asyncAfter(deadline: .now() + 10) {
self.enterFullscreen(playerViewController:self.playerController)
}
}
Don't forget that this solution based on private API calls that is not recommended to use.
As a little iOS 14 update to ToddH's answer: the private API to call is enterFullScreenAnimated:completionHandler:. So here's an extension on AVPlayerViewController to enter full screen.
extension AVPlayerViewController {
func enterFullScreen(animated: Bool) {
perform(NSSelectorFromString("enterFullScreenAnimated:completionHandler:"), with: animated, with: nil)
}
func exitFullScreen(animated: Bool) {
perform(NSSelectorFromString("exitFullScreenAnimated:completionHandler:"), with: animated, with: nil)
}
}
This implementation doesn't offer a completion callback. If you pass a Swift closure to the completionHandler parameter, it crashes in the underlying Obj-C API. I haven't investigated how to pass the closure to make it work.
Swift 3 version for the answer of ToddH:
extension AVPlayerViewController {
func goFullScreen() {
let selector = NSSelectorFromString("_transitionToFullScreenViewControllerAnimated:completionHandler:")
if self.responds(to: selector) {
// first argument is animated (true for me), second is completion handler (nil in my case)
self.perform(selector, with: true, with: nil)
}
}
}
You can just set the videoGravity property of AVPlayerViewController.
if(fullscreen)
{
[self.avPlayerController
setVideoGravity:AVLayerVideoGravityResizeAspectFill];
}
else
{
[self.avPlayerController
setVideoGravity:AVLayerVideoGravityResizeAspect];
}
For an 'embedded' AVPlayerViewController instance, it is quite easy to programmatically have it start playback in full screen mode, and without hacking anything (calling private methods). You just need to set its entersFullScreenWhenPlaybackBegins property to true.
You need to add the controller as a child VC to the main VC, and that's basically it. In viewDidAppear(_:) you need to call play() method on the controller's player property - playback will be automatically started in fullscreen.
It's often best to check Apple sample code for these kind of tricky APIs; I think this one might be useful for a lot of AVPlayer use cases: Using AVKit in iOS.
I did not have the need to use any restricted code.
For this, I am assuming that you have added the AVPlayerViewController as a child view controller.
Then for that you will first have to remove the child view controller and then present it again as a fullscreen controller as well attach the AVPlayer view properly to it's parent view.
Here is how I did it. Please note that I am using a library called Easy Peasy for restoring the playerVC.view constraints - one can do that with proper constraints as well.
#objc func fullscreenButtonClicked() {
playerVC.willMove(toParentViewController: nil)
playerVC.view.removeFromSuperview()
playerVC.removeFromParentViewController()
self.present(self.playerVC, animated: false, completion: {
self.playerVC.view.easy.layout(Top(), Right(), Left(), Bottom())
})
}
Its pretty simple, just set
playerViewController.videoGravity = .resizeAspectFill
and it goes full screen:)
I've spent quite a bit of time searching online and talking to other developers about this issue to no avail. The exact issue is described in this SO post (Focus on the UISearchBar but the keyboard not appear), although it's many years old.
I recently switched from using the deprecated UISearchDisplayController and UISearchBar in IB, and switched over to UISearchController via the code for iOS8.
The problem I'm getting however, is that focus is assigned correctly (you can tell because the cancel button animates to the right of the search bar after the view loads), however the keyboard does not show up.
Here's the code that I have.
.h
#property (nonatomic, strong) UISearchController *searchController;
.m
- (void)viewDidLoad {
[super viewDidLoad];
...
[self initializeSearchController];
....
}
- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
[self.searchController setActive:YES];
[self.searchController.searchBar becomeFirstResponder];
}
- (void)initializeSearchController {
self.searchController = [[UISearchController alloc] initWithSearchResultsController:nil];
self.searchController.searchResultsUpdater = self;
self.searchController.dimsBackgroundDuringPresentation = NO;
self.searchController.delegate = self;
self.searchController.searchBar.delegate = self;
[self.searchController.searchBar sizeToFit];
[self.tableView setTableHeaderView:self.searchController.searchBar];
self.definesPresentationContext = YES;
}
The things I've tried so far.
I've tried calling becomeFirstResponder on a 0.2 second delay, as suggested in another SO post.
I've set a breakpoint in viewDidAppear, and verified that both self.searchController and self.searchController.searchBar are both valid objects, neither nil.
I've tried conforming to the UISearchControllerDelegate and using the following snippet of code
here:
- (void)didPresentSearchController:(UISearchController *)searchController {
//no matter what code I put in here to becomeFirstResponder, it doesn't
//matter because this is never called, despite setting the
//self.searchController.delegate = self AND
//self.searchController.searchBar.delegate = self.
}
I've created a new view from scratch in storyboards, and segued to that one instead, to make sure I didn't have some old searchBar remnant in my view. This did not work either.
I've only tested this on a real device (iPhone 6), and it's not a simulator issue of not showing the keyboard.
I'm out of ideas, and I've seen every question and answer related to this one the web. Nothing is working.
To clarify again what's going on, the searchBar correctly becomes the first responder, the cancel button to the right of it animates onscreen proving this, but the keyboard does not appear and the cursor does not blink in the searchBar.
Your code looks ok. What you are describing isn't normal behaviour.
The first thing you can do is to create a new project with just the UISearchController functionality and see how it goes. You can edit your question with it so we'll have a better view.
There's a good example on how to implement UISearchController here: Sample-UISearchController
Adding:
-(void)viewDidAppear:(BOOL)animated
{
[super viewDidAppear:animated];
[self.searchController.searchBar becomeFirstResponder];
}
to MasterViewController_TableResults.m gave the expected results and the keyboard popped up on launch on an iPad & iPhone with iOS 8.3.
You can go over that project and see what you did differently,
Edit:
Apparently if [self.searchController setActive:YES] is called before becomeFirstResponder the keyboard won't show. I wonder if that's a bug or not.
Had the same annoying issue.
You would think that by setting the SearchController as active would both present the the search controller and the keyboard. Unfortunately, it only does the first part.
My solution
in viewDidAppear make the Search Controller active:
override func viewDidAppear(animated: Bool) {
super.viewDidAppear(animated)
resultSearchController.active = true
}
once it is active, in didPresentSearchController make as first responder
func didPresentSearchController(searchController: UISearchController) {
searchController.searchBar.becomeFirstResponder()
}
Swift 3.0 (iOS 10) working solution:
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
searchController.isActive = true
DispatchQueue.main.async { [unowned self] in
self.searchController.searchBar.becomeFirstResponder()
}
}
On iOS 9 I've found its sufficient to delay becomeFirstResponder() to the next run loop:
func focusSearchField() {
searchController?.active = true
// skipping to the next run loop is required, otherwise the keyboard does not appear
dispatch_async(dispatch_get_main_queue(), { [weak self] in
self?.searchController?.searchBar.becomeFirstResponder()
})
}
Working Solution:-
Don't use [self.searchController setActive:YES] before becomeFirstResponder.
- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
dispatch_async(dispatch_get_global_queue(0, 0), ^{
dispatch_async(dispatch_get_main_queue(), ^{
// [self.searchController setActive:YES];
[self.searchController.searchBar becomeFirstResponder];
});
});
}
In iOS 10, I had to run the code in delegate method on main thread. First I set the active to YES in viewDidAppear,
-(void)viewDidAppear:(BOOL)animated{
[super viewDidAppear:animated];
[self.searchController setActive:YES];
}
and then in the delegate method:
- (void)didPresentSearchController:(UISearchController *)searchController
{
dispatch_async(dispatch_get_main_queue(), ^{
[searchController.searchBar becomeFirstResponder];
});
}
The solution that will work is as follows :
1.Override ViewDidLayoutSubviews in the view controller in which you are showing UISearchController
2.Override ViewDidLayoutSubviews and inside it make search bar first responder.
Tested it on iOS > 9.0
Caution : Put a null check before making it First responder as follows
if((searchController != null)&&(searchController.SearchBar != null))
searchController.SearchBar.BecomeFirstResponder();
This is because ViewDidLayoutSubviews also gets called when cancel button is pressed.
This worked for me in Xamarin.
I had trouble with an UISearchBar not displaying the keyboard when doing
[searchBar becomeFirstResponder];
By searching on the net, i found this thread on the Apple developer website
that helped me to discover that the keyboard won't open if you don't have a keyWindow.
The application i work on do something like this :
Window A (KeyWindow)
do some things
open Window B (KeyWindow)
do some things
close Window B (resign KeyWindow)
I just had to do
[[[[UIApplication sharedApplication] windows] firstObject] makeKeyWindow];
after the resigning of window B and no more trouble with the keyboard.
This might also be related to Simulator Settings. Just disable Hardware -> Keyboard -> "Connect Hardware Keyboard" .
For further details: UISearchBar not showing keyboard when tapped
-(void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
[self.searchController setActive:YES];
}
//and then in the delegate method:
- (void)didPresentSearchController:(UISearchController *)searchController
{
dispatch_async(dispatch_get_main_queue(), ^{
[searchController.searchBar becomeFirstResponder];
});
}
//The above works for me in addition to this I had to add:
-(void)viewWillDisappear:(BOOL)animated {
[searchController setActive:NO];
}
I want to check the pasteboard and show an alert if it contains specific values when the view appears. I can place the code into viewDidLoad to ensure it's only invoked once, but the problem is that the alert view shows too quickly. I know I can set a timer to defer the alert's appearance, but it's not a good work-around I think.
I checked the question iOS 7 - Difference between viewDidLoad and viewDidAppear and found that there is one step for checking whether the view exists. So I wonder if there's any api for doing this?
Update: The "only once" means the lifetime of the view controller instance.
There is a standard, built-in method you can use for this.
Objective-C:
- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
if ([self isBeingPresented] || [self isMovingToParentViewController]) {
// Perform an action that will only be done once
}
}
Swift 3:
override func viewDidAppear(_ animated: Bool) {
super.viewDidAppear(animated)
if self.isBeingPresented || self.isMovingToParentViewController {
// Perform an action that will only be done once
}
}
The call to isBeingPresented is true when a view controller is first being shown as a result of being shown modally. isMovingToParentViewController is true when a view controller is first being pushed onto the navigation stack. One of the two will be true the first time the view controller appears.
No need to deal with BOOL ivars or any other trick to track the first call.
rmaddy's answers is really good but it does not solve the problem when the view controller is the root view controller of a navigation controller and all other containers that do not pass these flags to its child view controller.
So such situations i find best to use a flag and consume it later on.
#interface SomeViewController()
{
BOOL isfirstAppeareanceExecutionDone;
}
#end
#implementation SomeViewController
-(void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
if(isfirstAppeareanceExecutionDone == NO) {
// Do your stuff
isfirstAppeareanceExecutionDone = YES;
}
}
#end
If I understand your question correctly, you can simply set a BOOL variable to recognize that viewDidAppear has already been called, ex:
- (void)viewDidAppear {
if (!self.viewHasBeenSet) { // <-- BOOL default value equals NO
// Perform whatever code you'd like to perform
// the first time viewDidAppear is called
self.viewHasBeenSet = YES;
}
}
This solution will call viewDidAppear only once throughout the life cycle of the app even if you create the multiple object of the view controller this won't be called after one time. Please refer to the rmaddy's answer above
You can either perform selector in viewDidLoad or you can use dispatch_once_t in you viewDidAppear. If you find a better solution then please do share with me. This is how I do the stuff.
- (void)viewDidLoad {
[super viewDidLoad];
[self performSelector:#selector(myMethod) withObject:nil afterDelay:2.0];
}
- (void)viewDidAppear:(BOOL)animated {
[super viewDidAppear:animated];
static dispatch_once_t once;
dispatch_once(&once, ^{
//your stuff
[self myMethod];
});
}
By reading other comments (and based on #rmaddy 's answer), I know this is not what OP asked for, but for those who come here because of title of the question:
extension UIViewController {
var isPresentingForFirstTime: Bool {
return isBeingPresented() || isMovingToParentViewController()
}
}
UPDATE
You should use this method in viewDidAppear and viewWillAppear. (thanks to #rmaddy)
UPDATE 2
This method only works with modally presented view controllers and pushed view controllers. it's not working with a childViewController. using didMoveToParentViewController would be better with childViewControllers.
You shouldn't have issues in nested view controllers with this check
extension UIViewController {
var isPresentingForFirstTime: Bool {
if let parent = parent {
return parent.isPresentingForFirstTime
}
return isBeingPresented || isMovingFromParent
}
}
Try to set a BOOL value, when the situation happens call it.
#interface AViewController : UIViewController
#property(nonatomic) BOOL doSomeStuff;
#end
#implementation AViewController
- (void) viewWillAppear:(BOOL)animated
{
if(doSomeStuff)
{
[self doSomeStuff];
doSomeStuff = NO;
}
}
in somewhere you init AViewController instance:
AddEventViewController *ad = [AddEventViewController new];
ad.doSomeStuff = YES;
Not sure why you do this in ViewDidAppear? But if you want doSomeStuff is private and soSomeStuff was called only once, here is another solution by notification:
[[NSNotificationCenter defaultCenter] addObserver:self selector:#selector(doSomeStuff) name:#"do_some_stuff" object:nil];
- (void) doSomeStuff
{}
Then post when somewhere:
[[NSNotificationCenter defaultCenter] postNotificationName:#"do_some_stuff" object:nil];
swift 5
I've tried isBeingPresented() or isMovingToParent.
But It doesn't work.
So I tried below code. and It's work for me!
override func viewDidAppear(_ animated: Bool) {
if (self.isViewLoaded) {
// run only once
}
}
You can use this function in ViewDidLoad method
performSelector:withObject:afterDelay:
it will call that function after delay. so you don't have to use any custom timer object.
and For once you can use
dispatch_once DCD block.Just performSelector in the dispatch_once block it will call performSelector only once when ViewDidLoad is called
Hope it helps