Objective C / iOS Update Interval Issues Using Device Motion Manager

Question

Code is working to get motion and gyro updates, put into arrays respectively and select the max value in the array if a capture event occurs. Everything works if the device motion updates are set to .02 or .03; however, I am getting additional output/values when the updates are set to .01 which I need for my application. Any help or guidance would be greatly appreciated. Thanks in advance. Here is the code:`

#import "ViewController.h"
#import <CoreMotion/CoreMotion.h>

#define kRadToDeg   57.2957795

@interface ViewController ()
@property (weak, nonatomic) IBOutlet UILabel *pitchLabel;
@property (nonatomic, strong) CMMotionManager *motionManager;
@property (weak, nonatomic) IBOutlet UILabel *rotationXLabel;
@property (nonatomic, strong) CMDeviceMotion *motion;
@property (nonatomic, strong) NSMutableArray *pitchArray;
@property (nonatomic, strong) NSMutableArray *rotationArray;
@property (nonatomic) id maxRotation;
@property (nonatomic) id maxPitch;
@property BOOL captureValues;

@end

@implementation ViewController

- (CMMotionManager *)motionManager
{
    if (!_motionManager) {
    _motionManager = [CMMotionManager new];
    [_motionManager setDeviceMotionUpdateInterval:(.01)];
    [_motionManager setGyroUpdateInterval:(.01)];
}
return _motionManager;
}
- (void)viewDidLoad
{
[super viewDidLoad];
[self placePitchValuesInArray];
[self placeRotationValuesInArray];
}

-(void)placePitchValuesInArray {

NSMutableArray *pitchArray = [NSMutableArray array];
pitchArray = [[NSMutableArray  alloc] initWithCapacity:150];

if (_captureValues == NO) {

[self.motionManager startDeviceMotionUpdatesToQueue:[NSOperationQueue              currentQueue] withHandler:^(CMDeviceMotion *motion, NSError *error) {

 self.pitchLabel.text = [NSString stringWithFormat:@"%.2gº", motion.attitude.pitch * kRadToDeg];

[pitchArray addObject:[NSString stringWithFormat:@"%.2gº", motion.attitude.pitch *  kRadToDeg]];

        _pitchArray = pitchArray;

        if (pitchArray.count >= 150) {  //maintain running array of 150 pitch values

        [pitchArray removeObjectAtIndex:0];
        }
        id maxPitch = [_rotationArray valueForKeyPath:@"@max.intValue"];

        _maxPitch = maxPitch;

         [self checkCapture];

         }];

         }
      }

-(void)placeRotationValuesInArray {

NSMutableArray *rotationArray = [NSMutableArray array];

rotationArray = [[NSMutableArray  alloc] initWithCapacity:150 ];

if (self.captureValues == NO) {

    [self.motionManager startGyroUpdatesToQueue:[NSOperationQueue currentQueue]  withHandler:^(CMGyroData *gyroData, NSError *error) {

        self.rotationXLabel.text = [NSString stringWithFormat:@"%f",  gyroData.rotationRate.x];

        [rotationArray addObject:[NSString stringWithFormat:@"%f", gyroData.rotationRate.x]];

        _rotationArray = rotationArray;

        if (rotationArray.count >= 150) { //maintain running array of 150 rotaion  values

            [rotationArray removeObjectAtIndex:0];
        }

        id maxRotation = [rotationArray valueForKeyPath:@"@max.intValue"];

        _maxRotation = maxRotation;

        [self checkCapture];
        }];

       }
   }

 -(void)checkCapture {

//to generate capture. iPhone is landscape with HOME button on RIGHT. Tilt left side     UP slightly. ROTATE quickly in a counter-clockwise fashion.

if (([self.pitchLabel.text integerValue] > 3) && ([self.rotationXLabel.text   integerValue] > 5))
{
    (_captureValues = YES);
    [_motionManager stopDeviceMotionUpdates];
    [_motionManager stopGyroUpdates];

    for (int i=0; i<30; i++){ // modify pitchArray to remove last 30 values
        [self.pitchArray removeLastObject];

    }

    id maxPitch = [_pitchArray valueForKeyPath:@"@max.integerValue"];

    _maxPitch = maxPitch;

   [self outputValues];
}

}

-(void)outputValues {

NSLog(@"Max Pitch Value from modified array = %@", _maxPitch);
NSLog(@"Max Rotation Value = %@", _maxRotation);
sleep(2.5);
[self resetFlagAndArrays];

}
-(void)resetFlagAndArrays {

(_captureValues = NO);
[_pitchArray removeAllObjects];
[_rotationArray removeAllObjects];
[self viewDidLoad];

 }

 @end

`

Answer 1

Just wanted to share the solution for anyone with a similar issue. After stopping the device motion updates in the checkCapture method above, I added a delay and moved the "for loop" into a separate method - like this:

[self performSelector:@selector(adjustValues) withObject:nil afterDelay:.5];

-(void)adjustValues {
 for (int i=0; i<30; i++){ // modify pitchArray to remove last 30 values
    [self.pitchArray removeLastObject];

 }

 id maxPitch = [_pitchArray valueForKeyPath:@"@max.integerValue"];

 _maxPitch = maxPitch;

 [self outputValues];
 }

This solves the problem of data "leaking through" as the device motion updates appeared to be happening faster than the execution of the code when the update interval was set to .01.