ios检测设备摄像头、指南针、录音、陀螺仪的状态

//检查前后摄像头BOOL cameraAvailable = [UIImagePickerController isCameraDeviceAvailable:UIImagePickerControllerCameraDeviceRear];//前BOOL frontCameraAvailable = [UIImagePickerController isCameraDeviceAvailable:UIImagePickerControllerCameraDeviceFront];//后//检查指南针 CoreLocation.framework  <CoreLocation/CoreLocation.h>BOOL magnetometerAvailbale = [CLLocationManager headingAvailable];//检查声音支持 AVFoundation.framework <AVFoundation/AVFoundation.h>AVAudioSession *audioSession = [AVAudioSession sharedInstance];  //返回一个AVAudioSession实例BOOL audioAvailable = audioSession.inputAvailable;//bool值。获取是否支持//检查录像支持 MobileCoreServices.framework <MobileCoreServices/MobileCoreServices.h>- (BOOL)isvideoCameraAvailable{    //简单检查所有的可用的媒体资源类型，然后检查返回的数组，如果其中包含了kUTTypeMovie的NSString类型对象，就证明摄像头支持录像    UIImagePickerController *picker = [[UIImagePickerController alloc]init];    NSArray *sourceTypes = [UIImagePickerController availableMediaTypesForSourceType:picker.sourceType];//返回所支持的media的类型数组    [picker release];    if (![sourceTypes containsObject:(NSString *)kUTTypeMovie]) {//containsObject确定数组中是否包含后面的对象        return NO;    }    return YES;}    //检查陀螺仪可用 CoreMotion.framework <CoreMotion/CoreMotion.h>- (BOOL) isGyroscopeAvailable{#ifdef __IPHONE_4_0//4.0之后才有    CMMotionManager *motionManager = [[CMMotionManager alloc]init];    BOOL gyroscopeAvailable = motionManager.gyroAvailable;    [motionManager release];    return gyroscopeAvailable;#else    return NO;#endif}