26         
27         static NSInteger shakeCount=0;
28         static NSDate *shakeStart;
29         
30         NSDate *now=[[NSDate alloc] init];
31         //  摇晃 ２秒内
32  

           

 NSDate  *checkDate=[[NSDate  alloc]  initWithTimeInterval:2.0f 

sinceDate:shakeStart];
33         
34         //超过２秒  重计算晃动次数
35         if ([now compare:checkDate]==NSOrderedDescending||shakeStart==nil){
36                 shakeCount=0;
37                 [shakeStart release];
38                 shakeStart=[[NSDate alloc] init];                                
39         }
40         
41         [now release];
42         [checkDate release];
43         
44         // 三轴摇晃的 G 力超过２则 列入计次
45         if (fabsf(acceleration.x)>2.0 || fabsf(acceleration.y)>2.0|| fabsf(acceleration.z)>2.0){
46                 shakeCount++;
47                 
48                 //２秒内侦测到４次则判定为 Shake 摇晃手机
49                 if (shakeCount>4){
50                         shakeCount=0;
51                         [shakeStart release];
52                         shakeStart=[[NSDate alloc] init];
53                         
54                         //画面显示摇动文字
55                         mylabel.text=@"地震了";
56                         
57         //设定２秒后自动还原                
58  

           

 [NSTimer  scheduledTimerWithTimeInterval:2.0f  target:self 

selector:@selector(cleartext) userInfo:nil repeats:NO];
59                 }
60         }
61 }                
62                         
63 -(void)cleartext{
64         mylabel.text=@"没现象";
65 }