Objective-c 将 UIImagePickerController 更改为视频模式答案

【问题标题】：Objective-c Changing UIImagePickerController to video modeObjective-c 将 UIImagePickerController 更改为视频模式
【发布时间】：2011-09-22 14:02:17
【问题描述】：

我有一个应用程序，我希望它在后台显示来自摄像机的视频源。我的视图控制器中有以下代码：

#if !TARGET_IPHONE_SIMULATOR
    imagePickerController = [[UIImagePickerController alloc] initWithRootViewController:self];
    imagePickerController.delegate = self;
    imagePickerController.sourceType = UIImagePickerControllerSourceTypeCamera;

    imagePickerController.navigationBarHidden = YES;
    imagePickerController.toolbarHidden = NO;
    imagePickerController.showsCameraControls = NO;
    //...
    [self.view addSubview:self.imagePickerController.view];
    [imagePickerController viewWillAppear:YES];
    [imagePickerController viewDidAppear:YES];
 #endif 
   //...
  [self.view addSubview:otherthings];

然后我在顶部添加其他视图，我也有声音。但是，我将图像选择器模式更改为视频，但在播放声音时它会冻结。这是我改变的：

#if !TARGET_IPHONE_SIMULATOR
    imagePickerController = [[UIImagePickerController alloc] init];//initWithRootViewController:self];
    imagePickerController.delegate = self;
    imagePickerController.sourceType = UIImagePickerControllerSourceTypeCamera;

    NSArray *mediaTypes = [UIImagePickerController availableMediaTypesForSourceType:UIImagePickerControllerSourceTypeCamera];
    NSArray *videoMediaTypesOnly = [mediaTypes filteredArrayUsingPredicate:[NSPredicate predicateWithFormat:@"(SELF contains %@)", @"movie"]];
    BOOL movieOutputPossible = (videoMediaTypesOnly != nil);

    if (movieOutputPossible) {
        imagePickerController.mediaTypes = videoMediaTypesOnly;
        imagePickerController.videoQuality = UIImagePickerControllerQualityTypeHigh;
        imagePickerController.navigationBarHidden = YES;
        imagePickerController.toolbarHidden = YES;
        imagePickerController.showsCameraControls = NO;                      
    }


#endif

谁知道为什么当声音播放时相机选择器会冻结？顺便说一下，声音是一个 AVAudioPlayer。

【问题讨论】：

为什么在alloc的时候把rootViewController的定义去掉了？
不知道，试过之后它只会在我播放声音时冻结。为什么？
很可能你有一些东西在做自动释放，你应该分配你自己的东西来保存。具体来说，我将从这两行开始：(NSArray *mediaTypes =) 和 (NSArray *videoMediaTypesOnly =)。这些都是在您无法控制的情况下自动释放的，可能会导致问题。
即使我删除它并添加 imagePickerController.mediaTypes = [[NSArray alloc] initWithObjects: (NSString *) kUTTypeMovie, nil];播放声音时它仍然冻结。当声音结束时，相机并没有解冻。
不确定我明白了...您是说在播放 AVAudioPlayer 声音时电影播放冻结，然后在声音播放完毕后恢复播放？

标签： objective-c video uiimagepickercontroller

【解决方案1】：

解决方案：使用 AVFOundation 代替 UIImagePickerController。

    videoBackground = [[UIView alloc] initWithFrame:CGRectMake(0.0, 0.0, 320.0, 480.0)];

    AVCaptureSession *session = [[AVCaptureSession alloc] init];
    session.sessionPreset = AVCaptureSessionPresetMedium;


    CALayer *viewLayer = videoBackground.layer;
    NSLog(@"viewLayer = %@", viewLayer);

    AVCaptureVideoPreviewLayer *captureVideoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session];

    captureVideoPreviewLayer.frame = videoBackground.bounds;
    [videoBackground.layer addSublayer:captureVideoPreviewLayer];

    AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

    NSError *error = nil;
    AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];
    if (!input) {
        // Handle the error appropriately.
        NSLog(@"ERROR: trying to open camera: %@", error);
    }
    [session addInput:input];
    [session startRunning];
    [self.view addSubview:videoBackground];

【讨论】：