加速度

 ios提供了3个传感器，它们沿设备的垂直坐标测量加速度，即左/右(X)，上/下(Y)和前/后(Z)。这些值表示影响设备的力，即同时来自重力和用户移动的受力。

相关代码：

#import <UIKit/UIKit.h>
@interface ViewController : UIViewController<UIAccelerometerDelegate>
@property (strong, nonatomic) IBOutlet UIImageView *imgView;
@end

//
//  ViewController.m
//  DeviceTest
//  加速度
//  Created by Dwen on 12-11-19.
//  Copyright (c) 2012年 __MyCompanyName__. All rights reserved.
//

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController
@synthesize imgView;

- (void)viewDidLoad
{
    [super viewDidLoad];
    imgView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"arrow.png"]];
    imgView.frame = CGRectMake(300, 300, 200, 100);
    [self.view addSubview:imgView];
    
    //获取设备信息
    NSLog(@"%@",[[UIDevice currentDevice] systemName]);
    NSLog(@"%@",[[UIDevice currentDevice] systemVersion]);
    NSLog(@"%@",[[UIDevice currentDevice] model]);
    //设置代理
    [[UIAccelerometer sharedAccelerometer] setDelegate:self];
}

- (void)accelerometer:(UIAccelerometer *)accelerometer didAccelerate:(UIAcceleration *)acceleration{
    float xx = -[acceleration x];
	float yy = [acceleration y];
    float zz = [acceleration z];
	float angle = atan2(yy, xx);
    NSLog(@"xx: %g, yy: %g, zz: %g",xx,yy,zz);
	[imgView setTransform:CGAffineTransformMakeRotation(angle)];
}

- (void)viewDidUnload
{
    [self setImgView:nil];
    [super viewDidUnload];
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return YES;
}

@end