How to do some stuff in viewDidAppear only once?

Question

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 onl

Answer 1

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

Answer 2

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