Question

我无法弄清楚为什么滚动，俯仰和偏航值在记录时给出0.0000。我确信这是我想念的东西，但我无法弄清楚..

这是代码：

//ViewController.m

#import "ViewController.h"
@interface ViewController (){

}
@property (nonatomic) CMMotionManager *motionManager;

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    self.motionManager = [[CMMotionManager alloc] init];
    CMDeviceMotion *devMotion = [[CMDeviceMotion alloc]init];

    if ([self.motionManager isDeviceMotionAvailable]) {
        NSLog(@"Device Motion Available");
        [self.motionManager setDeviceMotionUpdateInterval:1.0/30.0];
        // Pull mechanism is used
        [self.motionManager startDeviceMotionUpdates];
    }
    devMotion = self.motionManager.deviceMotion;

    NSLog(@"Roll Pitch and Yaw are %f, %f, %f",devMotion.attitude.roll, devMotion.attitude.pitch, devMotion.attitude.yaw);

}

我已经通过这个类似的问题：SO Question

请帮我理解这个..

谢谢..

更新代码：

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    self.motionManager = [[CMMotionManager alloc] init];

    if ([self.motionManager isDeviceMotionAvailable]) {
        NSLog(@"Device Motion Available");
        [self.motionManager setDeviceMotionUpdateInterval:1.0/30.0];
        // Pull mechanism is used
        [self.motionManager startDeviceMotionUpdates];
    }
    CMDeviceMotion *devMotion = self.motionManager.deviceMotion;
    NSLog(@"*Roll,Pitch and Yaw are %f, %f, %f",devMotion.attitude.roll, devMotion.attitude.pitch, devMotion.attitude.yaw);

    self.timer = [NSTimer scheduledTimerWithTimeInterval:1.0/30.0 target:self selector:@selector(updateValues:) userInfo:nil repeats:YES];
}

-(void) updateValues:(NSTimer *)timer{
    CMDeviceMotion *currDeviceMotion = self.motionManager.deviceMotion;

    NSLog(@"Roll Pitch and Yaw are %f, %f, %f",currDeviceMotion.attitude.roll, currDeviceMotion.attitude.pitch, currDeviceMotion.attitude.yaw);


}

此代码的初始值也有很大一部分为0.000000。之后它开始获取值......所以我想startDeviceMotionUpdates为deviceMotion提供值时会有一些延迟。所以看起来我需要弄清楚如何保存第一个非零值。

Answer 1

请注意，devMotion变量不会立即保留可用值（或根本不保留任何值），因为CMMotionManager需要一段时间才能在deviceMotion之后更新startDeviceMotionUpdates属性。所以你应该有一些定期触发并读取该属性的计时器。您链接的文章做了类似的事情。
- 只要陀螺仪正在启动，deviceMotion属性将为空（您只看到0.0，因为到nil的消息返回零）。
作为旁注：您对[[CMDeviceMotion alloc] init]的调用毫无用处，因为您覆盖了使用self.motionManager.deviceMotion分配结果的变量。

Devicemotion不更新值

1 个答案: