having issue with scrolling image with gyroscope - ios

Question

I have a strange problem with iPad Air !!! , my code runs fine on iPad 3 , iPad 4 , iPhone 5S , iPod 5th Gen , but on iPad air , my image scrolls automatically without user rotate the device , here is my code :
#property (strong, nonatomic) CMMotionManager *motionManager;
self.mainScrollView.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);
self.mainScrollView.bounces = NO;
self.mainScrollView.userInteractionEnabled = NO;
//set up the image view
UIImage *image= [UIImage imageNamed:#"YOUR_IMAGE_NAME"];
UIImageView *movingImageView = [[UIImageView alloc]initWithImage:image];
[self.mainScrollView addSubview:movingImageView];
self.mainScrollView.contentSize = CGSizeMake(movingImageView.frame.size.width, self.mainScrollView.frame.size.height);
self.mainScrollView.contentOffset = CGPointMake((self.mainScrollView.contentSize.width - self.view.frame.size.width) / 2, 0);
//inital the motionManager and detec the Gyroscrope for every 1/60 second
//the interval may not need to be that fast
self.motionManager = [[CMMotionManager alloc] init];
self.motionManager.gyroUpdateInterval = 1/60;
//this is how fast the image should move when rotate the device, the larger the number, the less the roation required.
CGFloat motionMovingRate = 4;
//get the max and min offset x value
int maxXOffset = self.mainScrollView.contentSize.width - self.mainScrollView.frame.size.width;
int minXOffset = 0;
[self.motionManager startGyroUpdatesToQueue:[NSOperationQueue currentQueue]
withHandler:^(CMGyroData *gyroData, NSError *error) {
if (fabs(gyroData.rotationRate.y) >= 0.1) {
CGFloat targetX = self.mainScrollView.contentOffset.x - gyroData.rotationRate.y * motionMovingRate;
if(targetX > maxXOffset)
targetX = maxXOffset;
else if (targetX < minXOffset)
targetX = minXOffset;
self.mainScrollView.contentOffset = CGPointMake(targetX, 0);
}
}];
it's kind of animation !!! this code works fine on other devices ! any help ?Thanks

Answer 1

could you try the following:
This adds the error handling to your code, as an error may be returning from the gyroscope, and this may return a value >0.09; Use NSLOG more often when testing to pick apart your code and see what values are returning.
#property (strong, nonatomic) CMMotionManager *motionManager;
self.mainScrollView.frame = CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height);
self.mainScrollView.bounces = NO;
self.mainScrollView.userInteractionEnabled = NO;
//set up the image view
UIImage *image= [UIImage imageNamed:#"YOUR_IMAGE_NAME"];
UIImageView *movingImageView = [[UIImageView alloc]initWithImage:image];
[self.mainScrollView addSubview:movingImageView];
self.mainScrollView.contentSize = CGSizeMake(movingImageView.frame.size.width, self.mainScrollView.frame.size.height);
self.mainScrollView.contentOffset = CGPointMake((self.mainScrollView.contentSize.width - self.view.frame.size.width) / 2, 0);
//inital the motionManager and detec the Gyroscrope for every 1/60 second
//the interval may not need to be that fast
self.motionManager = [[CMMotionManager alloc] init];
self.motionManager.gyroUpdateInterval = 1/60;
//this is how fast the image should move when rotate the device, the larger the number, the less the roation required.
CGFloat motionMovingRate = 4;
//get the max and min offset x value
int maxXOffset = self.mainScrollView.contentSize.width - self.mainScrollView.frame.size.width;
int minXOffset = 0;
[self.motionManager startGyroUpdatesToQueue:[NSOperationQueue currentQueue]
withHandler:^(CMGyroData *gyroData, NSError *error) {
// IF NO ERROR ---
if(!error){
NSLog(#"No error from Gyroscope %f",gyroData.rotationRate.y);
if (fabs(gyroData.rotationRate.y) >= 0.1) {
NSLog(#"Moving image");
CGFloat targetX = self.mainScrollView.contentOffset.x - gyroData.rotationRate.y * motionMovingRate;
if(targetX > maxXOffset)
targetX = maxXOffset;
else if (targetX < minXOffset)
targetX = minXOffset;
self.mainScrollView.contentOffset = CGPointMake(targetX, 0);
}
}
// ERROR returned from GYRO
else NSLog(#"error recieved %#",error);
}];