iOS相机权限

BOOL isCameraValid = YES;  
//判断iOS7的宏，没有就自己写个，下边的方法是iOS7新加的，7以下调用会报错  
if(isIOS7AndLater)  
        {  
            AVAuthorizationStatus authStatus = [AVCaptureDevice authorizationStatusForMediaType:AVMediaTypeVideo];  
            if (authStatus != AVAuthorizationStatusAuthorized)  
            {  
                isCameraValid = NO;  
            }  
        }  
}