Executing methods one after another with pauses between executing

Question

Newbie obj-c question. I am writing a simple iPad presentation not for Appstore. My task is to implement few methods executed one after another with little pauses between them. Main structure looks like this: - view loads - two seconds pause, then executing method1 - two seconds pause, then executing method2 - two seconds pause, then executing method3 etc... First method I am calling from -viewDidLoad: ``` NSTimer *timer = [NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:@selector(firstCountStarts) userInfo:nil repeats:NO]; ``` Everything is ok here, method starts 2 seconds after view loads. From inside method1 I try to call method 2 in the same way but it start to execute simultaneously with method1. Same way triggered method3 (called from method2) and all methods after them not executed at all. I tried to situate all this methods in -ViewDidLoad and to call them with delays: ``` [self method1]; [self performSelector:@selector(method2) withObject:nil afterDelay:2]; [s…

Accepted Answer

You could add these to an NSOperation queue...

```
NSOperationQueue *queue = [NSOperationQueue new];

queue.maxConcurrentOperationCount = 1;

[queue  addOperationWithBlock:^{
    [self method1];
}];

[queue  addOperationWithBlock:^{
    [NSThread sleepForTimeInterval:2.0];
    [self method2];
}];

[queue  addOperationWithBlock:^{
    [NSThread sleepForTimeInterval:2.0];
    [self method3];
}];

...
```

This will then run each one only after the previous one has finished and put the 2 second delay in for you.

Careful about using this to do an UI stuff though. This will run in a Background thread so you may need to deal with that.

Maybe this might work better you could do it by subclassing NSOperation but that's a lot of work for not much benefit.

Run this from where ever you want, I suggest putting all this into a function called setUpQueue or something.

Then from viewWillAppear or viewDidLoad or somewhere else, on a button press, etc... do...

```
[self setUpQueue];
```

All you have to do is add stuff to the queue, the queue will then manage itself.

Executing methods one after another with pauses between executing

Solution

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