iPhone 開發筆記12: accelerometer 加速計

A. 在 xxx project 的 .h 檔 Class 宣告裡, 新增協定: <UIAccelerometerDelegate>

B. 在 xxx project 的 .m 檔的 Class 定義裡:

// Constant for the number of times per second (Hertz) to acceleration.
#define kAccelerometerFrequency 50
....
// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad {
    [super viewDidLoad];
....

    // Configure and start the accelerometer
    [[UIAccelerometer sharedAccelerometer] setUpdateInterval:(1.0 / kAccelerometerFrequency)];

    [[UIAccelerometer sharedAccelerometer] setDelegate:self]; // .h => : <UIAccelerometerDelegate>
}

// UIAccelerometerDelegate method, called when the device accelerates.
- (void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration
{
    CGRect greenFrame = racquet_green.frame;
    greenFrame.origin.x = greenFrame.origin.x + acceleration.x;
    racquet_green.frame = greenFrame;
    /*
     NSLog(@"accelerometer");
     NSLog(@"x:%f",acceleration.x); // -1 ~ 1
     NSLog(@"y:%f",acceleration.y); // -1 ~ 1
     NSLog(@"z:%f",acceleration.z);
     */
}