Devicemotion沒有更新值

Question

我無法弄清楚爲什麼滾動，俯仰和偏航值在登錄時給出了0.0000 ..我確定這是一個我想念的東西，但我無法弄清楚它..

這是代碼：

//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); 

} 

我已經通過這個類似的問題：SO Question

請幫助我瞭解這個..

謝謝..

---

更新的代碼：

@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); 


} 

該代碼也有它的初始值作爲0.000000的很大一部分。之後，它開始變得值...所以我想有是向deviceMotion提供值一些延遲startDeviceMotionUpdates。所以看起來我需要弄清楚如何保存第一個非零值。

您 devMotion變量將不會舉行可用值（或全部）馬上爲 CMMotionManager

Answer 1

• 通知需要一段時間startDeviceMotionUpdates後更新deviceMotion屬性。所以你應該有一些定期觸發的定時器並讀取該屬性。你的鏈接文章做類似的事情。
  • 只要陀螺儀啓動，deviceMotion屬性將爲空（你只看到0.0因爲消息nil返回零）。
• 作爲旁註：您撥打[[CMDeviceMotion alloc] init]是無用的，因爲您隨後覆蓋變量，結果被分配給self.motionManager.deviceMotion。