VisualizerView.h

#import <UIKit/UIKit.h>
#import <AVFoundation/AVFoundation.h>

@interface VisualizerView : UIView

@property (strong, nonatomic) AVAudioPlayer *audioPlayer;
@property (nonatomic, assign) NSInteger numberOfBars;

@end

VisualizerView.mm

#import "VisualizerView.h"
#import "MeterTable.h"

@implementation VisualizerView {
    MeterTable meterTable;
    NSMutableArray *_barsArray;
}


- (id)initWithCoder:(NSCoder *)aDecoder
{
    self = [super initWithCoder:aDecoder];
    
    _numberOfBars = 8;
    _barsArray = [NSMutableArray array];
    
    float halfContainerWidth = self.frame.size.width / 2;
    
    float barContainerWidth = halfContainerWidth / _numberOfBars;
    float barWidth = barContainerWidth / 2;
    
    if (self) {
        [self setBackgroundColor:[UIColor blackColor]];
        
        for (int i = 0; i < _numberOfBars; i++) {
            
            CAShapeLayer *barLayer = [CAShapeLayer layer];
                    
            float barOriginX = (i * barContainerWidth) + barWidth;

            [barLayer setPath:[[UIBezierPath bezierPathWithRect:CGRectMake(barOriginX,
                                                                           0,
                                                                           barWidth,
                                                                           self.frame.size.height / 3)] CGPath]];
            [barLayer setFillColor:[[UIColor whiteColor] CGColor]];
            
            [self.layer addSublayer:barLayer];
            [_barsArray addObject:barLayer];
            
            CAShapeLayer *oppositeBarLayer = [CAShapeLayer layer];
            float oppositeBarOriginX = self.bounds.size.width - barOriginX;

            [oppositeBarLayer setPath:[[UIBezierPath bezierPathWithRect:CGRectMake(oppositeBarOriginX,
                                                                                   0,
                                                                                   barWidth,
                                                                                   self.frame.size.height / 3)] CGPath]];
            [oppositeBarLayer setFillColor:[[UIColor whiteColor] CGColor]];
            [self.layer addSublayer:oppositeBarLayer];
            [_barsArray addObject:oppositeBarLayer];
        }
        
        self.layer.transform = CATransform3DMakeRotation(M_PI, 1.0f, 0.0f, 0.0f);
        
        CADisplayLink *dpLink = [CADisplayLink displayLinkWithTarget:self selector:@selector(update)];
        [dpLink addToRunLoop:[NSRunLoop currentRunLoop] forMode:NSRunLoopCommonModes];
    }
    
    
    
    return self;
}

- (void)update
{
    float scale = 0.5;
    if (_audioPlayer.playing )
    {
        self.hidden = NO;
        [_audioPlayer updateMeters];
        
        float power = 0.0f;
        for (int i = 0; i < [_audioPlayer numberOfChannels]; i++) {
            power += [_audioPlayer averagePowerForChannel:i];
        }
        power /= [_audioPlayer numberOfChannels];
        
        float level = meterTable.ValueAt(power);
        scale = level * 5;
        
    } else {
        self.hidden = YES;
    }

    for (int i = 0; i < _barsArray.count; i = i+2) {
        
        CGFloat transformScale = i * scale;
        
        transformScale = fmod(transformScale, 4);

        CAShapeLayer *barLayer = _barsArray[i];
        barLayer.transform = CATransform3DMakeScale(1, transformScale, 1);
        
        CAShapeLayer *oppositeBarLayer = _barsArray[i+1];
        oppositeBarLayer.transform = CATransform3DMakeScale(1, transformScale, 1);
    }
    
}

@end