Question: Just wondering how easy to do something like this in Iphone.

will Like to how to make the needle move

Thanks for reading and comments

![enter image description here](https://i.stack.imgur.com/KfCjP.jpg)

Answer: 
You should be able to put the needle in an `UIImageView`. Every view now has an associated transformation, this is basically a matrix, which decides how original points are mapped to the screen. There are quite simple ways to do a simple manipulation of this:

```
UILabel *lblTest = [[UILabel alloc] initWithFrame:CGRectMake(100, 100, 100, 100)];
lblTest.text = @"Testing";
[view addSubview:lblTest];

lblTest.transform = CGAffineTransformMakeRotation(M_PI / 4.0);

```

will result in the label being rotated by 45 degrees (which is a quarter of PI in radians; you can convert degrees to radians by multiplying by M\_PI and dividing by 180.0). Using this you already have the methods at hand to animate the needle whenever a new data point comes in.

Note that this can also be animated:

```
[UIView animateWithDuration:5.0 animations:^{
    lblTest.transform = CGAffineTransformMakeRotation(M_PI_4);
}];

```

This would slowly rotate the view to 45 degrees over the course of 5 seconds. There are some tutorials out there for animations, e.g. [How to use UIView animation tutorial](http://www.raywenderlich.com/2454/how-to-use-uiview-animation-tutorial). And the framework already allows for some advanced things, e.g.:

```
[UIView animateWithDuration:1.0 delay:1.0 options:UIViewAnimationCurveEaseInOut|UIViewAnimationOptionAutoreverse|UIViewAnimationOptionRepeat animations:^{
    lblTest.transform = CGAffineTransformMakeRotation(M_PI_4);
} completion:^(BOOL finished) {        
}];

```

Will "smooth" beginning and end of the rotation, automatically reverse back and repeat this over and over. This results in the label "wiggeling" back and forth after waiting for 1 second.

You can use this to introduce some smooth effects when jumping between values. If you for example sample data only every 250ms, you might use that time to introduce some animation.
It depends how much experience you have in objc :)
But representing analog value with a gauge like this
is not too complicated. 

[This](http://www.cimgf.com/2008/10/25/core-animation-tutorial-slider-based-layer-rotation/) link for example should get you started...