Change Image Size With Slider and Also with Max value To Min Value(Opposite Direction Logic )

Here in my app Big To Small Slider Image Display so i create bellow logic and complete the work...

In Bellow Method i zoom in and zoom out the Image with Slider....

-(IBAction)scaleOfImage:(id)sender{

    float finalval,fixfinal;

    if (sldBigSmall.value<500) {

        finalval=500-sldBigSmall.value;

        fixfinal=500+finalval;

    }

    else if(sldBigSmall.value>500){

        finalval=sldBigSmall.value-500;

        fixfinal=500-finalval;

    }

    else{

        finalval=500;

    }

    

    if (boolimgplant) {

        

        imgplant.frame=CGRectMake(imgplant.frame.origin.x, imgplant.frame.origin.y, fixfinal, fixfinal);

        [imgplant setCenter:CGPointMake(500, 300)];

    }

    else if(boolimgpot){

        imgpot.frame=CGRectMake(imgpot.frame.origin.x, imgpot.frame.origin.y, fixfinal,fixfinal);

        [imgpot setCenter:CGPointMake(500, 400)];

    }

}