为什么当我使用 UIImagePickerController 时我的相机界面表现得很奇怪？

Question

在我的应用程序中，我希望用户能够拍照或使用照片库中的一张照片。当用户单击我制作的按钮时，会弹出一个警报视图，用户可以选择拍摄新照片或从照片库中拍摄一张照片。这是我使用的代码：

    - (void)PictureAlert:(id)sender {

    UIAlertView *AlertDialog;

    // Setting up AlertDialog.
    AlertDialog = [[UIAlertView alloc] initWithTitle:nil 
                                             message:nil 
                                            delegate:self 
                                   cancelButtonTitle:@"Cancel" 
                                   otherButtonTitles:@"Choose From Library", @"Take New Picture", nil];

    [AlertDialog show]; }

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex {

    NSString *ButtonTitle = [alertView buttonTitleAtIndex:buttonIndex];

    if ([ButtonTitle isEqualToString:@"Choose From Library"]) {

        if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]) {

            // Pick photo.
            UIImagePickerController *picker = [[UIImagePickerController alloc] init];
            picker.delegate = self;
            picker.allowsEditing = YES;
            picker.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;

            [self presentModalViewController:picker animated:YES];


        } else if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]) {

            // Setting up AlertDialog.
            UIAlertView *AlertDialog;

            AlertDialog = [[UIAlertView alloc] initWithTitle:@"Error accessing photo library" 
                                                     message:@"Device does not support a photo library"  
                                                    delegate:self 
                                           cancelButtonTitle:@"Dismiss" 
                                           otherButtonTitles:nil];

            [AlertDialog show];

        }


    } else if ([ButtonTitle isEqualToString:@"Take New Picture"]) {

        if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {

            // Take new photo.
            UIImagePickerController *picker = [[UIImagePickerController alloc] init];
            picker.delegate = self;
            picker.allowsEditing = YES;
            picker.wantsFullScreenLayout = YES;
            picker.sourceType = UIImagePickerControllerSourceTypeCamera;

            [self presentModalViewController:picker animated:YES];


        } else if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {

            // Setting up AlertDialog.
            UIAlertView *AlertDialog;

            AlertDialog = [[UIAlertView alloc] initWithTitle:@"Error accessing camera" 
                                                     message:@"Device does not support a camera"  
                                                    delegate:self 
                                           cancelButtonTitle:@"Dismiss" 
                                           otherButtonTitles:nil];

            [AlertDialog show];

        }

    }

}

问题是，如果用户想要拍摄新照片，则会弹出相机界面，然后如果旋转设备，界面将如下所示：

然后当用户将其旋转回来时，它突然看起来像这样：

一个小问题是相机需要很长时间才能加载。

任何想法将不胜感激:)

Answer 1

您可能需要考虑的一些事项：

1. 将 wantsFullScreenLayout 属性设置为 YES 将导致视图忽略状态栏。但由于您使用的是默认相机控件，状态栏会自动隐藏。这是图像底部出现 20 像素灰色区域的最可能原因。

2. 默认相机控件仅设计为纵向模式。由于您的第一张图像看起来像是您以某种方式旋转了屏幕，因此您应该查看您的代码（可能是 shouldAutoRotate）并了解为什么要这样旋转视图。这应该可以解决横向图片中的缩放问题。

3. 如果您创建一个 UIImagePickerController 并呈现它，然后没有引用它以稍后释放它，则会出现内存泄漏。我建议在界面中设置 UIImagePickerController ，并在 viewDidLoad 方法中设置它。尝试：

.h

@interface yourView:UIViewController <UIImagePickerControllerDelegate> {
  UIImagePickerController * picker;
}

.m

- (void)dealloc; {
  [picker release];
  [super dealloc];
}

- (void)viewDidLoad; {
  [super viewDidLoad];
  picker = [[UIImagePickerController alloc] init];
  picker.delegate = self;
  picker.allowsEditing = YES;
  picker.sourceType = UIImagePickerControllerSourceTypeCamera;
}

- (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex; {
  NSString *ButtonTitle = [alertView buttonTitleAtIndex:buttonIndex];

  if([ButtonTitle isEqualToString:@"Choose From Library"]){
    if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypePhotoLibrary]){
      picker.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;
      [self presentModalViewController:picker animated:YES];
    }
    else{
      // Setting up AlertDialog.
      UIAlertView *AlertDialog;
      AlertDialog = [[UIAlertView alloc] initWithTitle:@"Error accessing camera" 
                                               message:@"Device does not support a camera"  
                                              delegate:self 
                                     cancelButtonTitle:@"Dismiss" 
                                     otherButtonTitles:nil];
      [AlertDialog show];
      [AlertDialog release];
    }
  }
  else if([ButtonTitle isEqualToString:@"Take New Picture"]){
    if ([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]) {
      picker.sourceType = UIImagePickerControllerSourceTypeCamera;
      [self presentModalViewController:picker animated:YES];
    }
    else{
      // Setting up AlertDialog.
      UIAlertView *AlertDialog;
      AlertDialog = [[UIAlertView alloc] initWithTitle:@"Error accessing camera" 
                                               message:@"Device does not support a camera"  
                                              delegate:self 
                                     cancelButtonTitle:@"Dismiss" 
                                     otherButtonTitles:nil];
      [AlertDialog show];
      [AlertDialog release];
    }
  }
}

这应该可以清除内存泄漏，并缩短加载时间。希望有帮助！

Answer 2

有时，如果您使用的是具有当前操作系统的老一代 iPhone，例如您使用的是 iPhone 3G，并将其 ios 更新到 ios5，那么您安装的某些应用程序的行为可能会有所不同，您可以将您的应用程序检查到另一台设备以进行纠正你的问题。

Answer 3

确保使用 mainWindow.rootViewController 和 [vc addChildViewController:] 设置视图控制器层次结构。这会将方向信息传播到您需要的地方。

Answer 4

对于我的项目来说，发生这种情况似乎是因为您没有在根视图控制器中编写 shouldAutoRotateToInterface: 方法。当调用 UIImagePickerController 时，旋转消息会一直传播到根视图控制器的 shouldAutoRotateToInterface 委托。您的方法应该如下所示：

- (BOOL)shouldAutorotateToInterfaceOrientation(UIInterfaceOrientation)interfaceOrientation
{
    // Return YES for supported orientations
    return (interfaceOrientation == UIInterfaceOrientationPortrait);
}

当我将项目升级到 iOS 5 时，我从 iOS 3 项目借用了根视图控制器。 iOS 3 没有自动在视图控制器类中编写此方法，请尝试一下并告诉我。