iOS判斷手機是否開啟麥克風

//判斷是否允許使用麥克風7.0新增的方法requestRecordPermission
-(BOOL)canRecord
{
    __block BOOL bCanRecord = YES;
    if ([[[UIDevice currentDevice] systemVersion] compare:@"7.0"] != NSOrderedAscending)
    {
        AVAudioSession *audioSession = [AVAudioSession sharedInstance];
        if ([audioSession respondsToSelector:@selector(requestRecordPermission:)]) {
            [audioSession performSelector:@selector(requestRecordPermission:) withObject:^(BOOL granted) {
                if (granted) {
                    bCanRecord = YES;
                }
                else {
                    bCanRecord = NO;
                    dispatch_async(dispatch_get_main_queue(), ^{
                        [[[UIAlertView alloc] initWithTitle:nil
                                                    message:@"app需要訪問您的麥克風。\n請啟用麥克風-設置/隱私/麥克風"
                                                   delegate:nil
                                          cancelButtonTitle:@"關閉"
                                          otherButtonTitles:nil] show];
                    });
                }
            }];
        }
    }
    
    return bCanRecord;
}