IOS錄音：錄音權限

在IOS上錄音，須要先得到權限，否則錄音只能返回空數據。

得到權限有兩步：

1.Info設置

在Xcode->Info->Custom iOS target properties裏，添加Privacy-Microphone Usage Description設置，並填寫一段描述。

2.代碼中動態申請

//recordPermission獲取當前的權限狀況
//requestRecordPermission 申請權限
-(void)checkRecordPermission{
    AVAudioSession* session = [AVAudioSession sharedInstance];
    AVAudioSessionRecordPermission recordPermission = [session recordPermission];
    if( recordPermission == AVAudioSessionRecordPermissionUndetermined )
    {
        NSLog(@"record permission:%d", recordPermission );
        if( [session respondsToSelector:@selector( requestRecordPermission:)])
        {
            [session requestRecordPermission:^(BOOL granted) {
                if( granted )
                {
                    NSLog(@"get record permission");
                }
                else{
                    NSLog(@"not permit record");
                }
            }];
        }
    }
    else{
        if( recordPermission == AVAudioSessionRecordPermissionGranted )
        {
            NSLog(@"already get record permission");
        }
        else{
            NSLog(@"already denied record permission ,please set in settings");
        }
    }
}