How to run code after some delay in Flutter?

I'd like to execute a function after a certain delay after my Widget is built. What's the idiomatic way of doing this in Flutter?

What I'm trying to achieve: I'd like to start with a default FlutterLogo Widget and then change its style property after some duration.

You can use Future.delayed to run your code after some time. e.g.:

Future.delayed(const Duration(milliseconds: 500), () {

// Here you can write your code

  setState(() {
    // Here you can write your code for open new view
  });

});

In setState function, you can write a code which is related to app UI e.g. refresh screen data, change label text, etc.

> Trigger actions after countdown

Timer(Duration(seconds: 3), () {
  print("Yeah, this line is printed after 3 seconds");
});

> Repeat actions

Timer.periodic(Duration(seconds: 5), (timer) {
  print(DateTime.now());
});

> Trigger timer immediately

Timer(Duration(seconds: 0), () {
  print("Yeah, this line is printed immediately");
});

Figured it out 

class AnimatedFlutterLogo extends StatefulWidget {
  @override
  State<StatefulWidget> createState() => new _AnimatedFlutterLogoState();
}

class _AnimatedFlutterLogoState extends State<AnimatedFlutterLogo> {
  Timer _timer;
  FlutterLogoStyle _logoStyle = FlutterLogoStyle.markOnly;

  _AnimatedFlutterLogoState() {
    _timer = new Timer(const Duration(milliseconds: 400), () {
      setState(() {
        _logoStyle = FlutterLogoStyle.horizontal;
      });
    });
  }

  @override
  void dispose() {
    super.dispose();
    _timer.cancel();
  }

  @override
  Widget build(BuildContext context) {
    return new FlutterLogo(
      size: 200.0,
      textColor: Palette.white,
      style: _logoStyle,
    );
  }
}

Just leaving here the snippet everyone is looking for:

Future.delayed(Duration(milliseconds: 100), () {
  // Do something
});

(Adding response on old q as this is the top result on google)

I tried yielding a new state in the callback within a bloc, and it didn't work. Tried with Timer and Future.delayed.

However, what did work was...

await Future.delayed(const Duration(milliseconds: 500));

yield newState;

Awaiting an empty future then running the function afterwards.

Just adding more description over the above answers

The Timer functionality works with below duration time also:

const Duration(
      {int days = 0,
      int hours = 0,
      int minutes = 0,
      int seconds = 0,
      int milliseconds = 0,
      int microseconds = 0})

Example:

  Timer(Duration(seconds: 3), () {
    print("print after every 3 seconds");
  });

Future.delayed(Duration(seconds: 3) , your_function)

Synchronously

Future.delayed(Duration(milliseconds: 1000), () {
    // Your code
});

---

Asynchronously

await Future.delayed(const Duration(milliseconds: 1000));

import 'dart:async';   
Timer timer;

void autoPress(){
  timer = new Timer(const Duration(seconds:2),(){
    print("This line will print after two seconds");
 });
}

autoPress();

A quick way is using Future.delayed as below:

Future.delayed(Duration(seconds: 10), (){
    print("Wait for 10 seconds");
});

or you can change duration to milliseconds like this:

Future.delayed(Duration(milliseconds: 3000), () {
        print("Wait for 3000 milliseconds");
});