Gauge animation on iphone

I'm trying to implement a gauge animation using (+ and - buttons) on iphone, but i have no idea where to start? Any help is really welcome. See the image below (开发者_JAVA百科this is what I'm trying to do). Thanks for your help.

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Here is some open source code (with an example) that implements the gauge view. You of course would still need to do the buttons yourself, and possible add a different visual style.

http://www.cocoacontrols.com/platforms/ios/controls/meterview

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You need to rotate the needle based on the angle... Here is the logic You can refer my answer here... Rotating a UIImageView around a point over 10 seconds?

    fireInterval = 10;
//Adjust starting and ending angle
    mStartingAngle = 45; 
    mEndingAngle = 180;
//Implementation

-(void) startTimer
{
 mPreviousTime = [NSDate timeIntervalSinceReferenceDate];
}

In the loop

-(void) updateFunction
{
    NSTimeInterval timeNow = [NSDate timeIntervalSinceReferenceDate];

            //NewValue = (((OldValue - OldMin) * (NewMax - NewMin)) / (OldMax - OldMin)) + NewMin
            //Mapping values between mStartAngle and mEndAngle
            mCurrentAngle = (((timeNow - mPreviousTime) * (mEndingAngle - mStartingAngle)) / (previousTime+fireInterval - mPreviousTime)) + mStartingAngle;

            if( mPreviousTime + fireInterval <= timeNow )
            {
                NSLog(@"10 seconds completed");
                mPreviousTime = timeNow;
            }
}

And rotate the needle based on mCurrentAngle....