ios - CMMotionManager：设备校准在真实设备上不起作用

Question

我对 CMMotionManager 有一个奇怪的行为。我尝试校准设备的位置以使我的应用程序支持多个设备方向。

当我在真实设备（不在模拟器中）上调试我的应用程序时，一切正常。当我在没有调试的情况下运行同一个应用程序时，校准不起作用。

这是我的代码：

static CMMotionManager* _motionManager;
static CMAttitude* _referenceAttitude;

// Returns a vector with the current orientation values
// At the first call a reference orientation is saved to ensure the motion detection works for multiple device positions
+(GLKVector3)getMotionVectorWithLowPass{
    // Motion
    CMAttitude *attitude = self.getMotionManager.deviceMotion.attitude;
    if (_referenceAttitude==nil) {
        // Cache Start Orientation
        _referenceAttitude = [_motionManager.deviceMotion.attitude copy];
    } else {
        // Use start orientation to calibrate
        [attitude multiplyByInverseOfAttitude:_referenceAttitude];
        NSLog(@"roll: %f", attitude.roll);
    }
    return [self lowPassWithVector: GLKVector3Make(attitude.pitch,attitude.roll,attitude.yaw)];
}

+(CMMotionManager*)getMotionManager {
    if (_motionManager==nil) {
        _motionManager=[[CMMotionManager alloc]init];
        _motionManager.deviceMotionUpdateInterval=0.25;
        [_motionManager startDeviceMotionUpdates];
    }
    return _motionManager;
}

Answer 1

我找到了解决方案。该问题是由于调试和非调试模式之间的不同时序行为引起的。CMMotionManager 在返回正确值之前需要一点时间进行初始化。解决方案是将校准推迟 0.25 秒。

此代码有效：

+(GLKVector3)getMotionVectorWithLowPass{
    // Motion
    CMAttitude *attitude = self.getMotionManager.deviceMotion.attitude;
    if (_referenceAttitude==nil) {
        // Cache Start Orientation
        // NEW:
        [self performSelector:@selector(calibrate) withObject:nil afterDelay:0.25];

    } else {
        // Use start orientation to calibrate
        [attitude multiplyByInverseOfAttitude:_referenceAttitude];
        NSLog(@"roll: %f", attitude.roll);
    }
    return [self lowPassWithVector: GLKVector3Make(attitude.pitch,attitude.roll,attitude.yaw)];
}

// NEW:
+(void)calibrate  
      _referenceAttitude = [self.getMotionManager.deviceMotion.attitude copy]
}