UIImagePIckerController 出现但相机不启动答案

【问题标题】：UIImagePIckerController appears but the camera does not startUIImagePIckerController 出现但相机不启动
【发布时间】：2013-01-01 19:47:28
【问题描述】：

是的，这可能是this 的重复问题。但由于没有得到答案，我将更具体的案例和代码：

我有 3 个参与UIViewControllers：

WelcomeView - 第一个
TakePhotoViewController - 第二个是 OverlayviewController 的代表
OverlayViewController - 相机的自定义视图。

场景：

用户输入WelcomeView，点击一个按钮，转至TakeView。
UIImageViewController 正在打开拍照。
用户单击取消按钮 - 正在调用 TakePhotoViewController 中的 didCancelCamera 方法并返回到 WelcomeView
用户离开应用程序。
用户重新打开应用并再次执行第 1 步。

图像选择器未打开。我可以拍照，没关系 - 但用户看不到他在拍什么。

OverlayViewController.h

@interface OverlayViewController : BaseViewController<UIImagePickerControllerDelegate,UINavigationControllerDelegate>
@property (nonatomic,weak) id<OverlayViewControllerDelegate> delegate;
@property (nonatomic,retain) UIImagePickerController *imagePickerController;
@end

OverlayViewController.m:


- (id)initWithCoder:(NSCoder *)aDecoder
{
    self = [super initWithCoder:aDecoder];
    if (self) {
        self.imagePickerController = [[UIImagePickerController alloc] init];
        self.imagePickerController.delegate = self;
    }
    return self;
}


- (void)viewDidLoad
{   
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor clearColor];
}

- (IBAction)takePicture:(id)sender {
    [self.imagePickerController takePicture];
}

- (IBAction)cancelImagePicker:(id)sender {
    [self.delegate didCancelCamera];
}

- (void) setupImagePicker:(UIImagePickerControllerSourceType) sourceType
{
    self.imagePickerController.sourceType = sourceType;
    if (sourceType == UIImagePickerControllerSourceTypeCamera)
    {
        self.imagePickerController.showsCameraControls = NO;
        if ([[self.imagePickerController.cameraOverlayView subviews] count] ==0)
        {
            CGRect overlayViewFrame = self.imagePickerController.cameraOverlayView.frame;
            CGRect newFrame = CGRectMake(0.0, CGRectGetHeight(overlayViewFrame)-self.view.frame.size.height-10.0, CGRectGetWidth(overlayViewFrame), self.view.frame.size.height + 10.0);
            self.view.frame = newFrame;
            [self.imagePickerController.cameraOverlayView addSubview:self.view];
        }
    }
}


- (void)finishAndUpdate
{
    [NSThread detachNewThreadSelector:@selector(threadStartAnimating:) toTarget:self withObject:nil];
    [self.delegate didFinishWithCamera];  // tell our delegate we are done with the camera
}

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    [self finishAndUpdate];
}

TakePhotoViewController.h

@interface TakePhotoViewController : BaseViewController<UIImagePickerControllerDelegate,UINavigationControllerDelegate,OverlayViewControllerDelegate>
@property (nonatomic, retain) OverlayViewController *overlayViewController;
@end

TakePhotoViewController.m

- (void)viewDidLoad
{
    [super viewDidLoad];
    UIStoryboard *sb = [UIStoryboard storyboardWithName:@"MainStoryboard" bundle:nil];
    // Insert the overlay
    self.overlayViewController = (OverlayViewController *)[sb instantiateViewControllerWithIdentifier:@"Overlay"];
    self.overlayViewController.delegate = self;   
}
- (void)viewDidUnload
{
    self.overlayViewController = nil;
    [super viewDidUnload];
    // Release any retained subviews of the main view.
}
- (void)openImagePicker {
   if([UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera]){
       [self showImagePicker:UIImagePickerControllerSourceTypeCamera];
   }
   else{
       [self showImagePicker:UIImagePickerControllerSourceTypePhotoLibrary];
   }
}

- (void)viewDidAppear:(BOOL)animated{
    if (appDelegate.shouldOpenPicker){
      [self openImagePicker];
    }
}
- (void)showImagePicker:(UIImagePickerControllerSourceType)sourceType
{

    if ([UIImagePickerController isSourceTypeAvailable:sourceType])
    {
       [self.overlayViewController setupImagePicker:sourceType];
       [self presentViewController:self.overlayViewController.imagePickerController animated:YES completion:nil];
    }
}
-(void)didCancelCamera{
    [[self.overlayViewController.imagePickerController presentingViewController] dismissViewControllerAnimated:NO completion:^ {
        [self performSegueWithIdentifier:@"fromTakeToWelcome" sender:self];
    }];

}

【问题讨论】：

你是在 iphone 还是 ipad 上测试？
iPhone 和 iPad 有同样的问题。我都试过了
你是否将OverlayViewController的view的背景颜色设置为清除？
@rdelmar 是的。在 viewDidLoad 方法中。对不起，我忘了在上面添加它，但我编辑了我的问题
您是否尝试过调试应用并查看是否有任何条件失败？

标签： objective-c uiviewcontroller uiimagepickercontroller xcode4.5

【解决方案1】：

我发现了错误。

方法

当用户在OverlayViewController 中单击- (IBAction)cancelImagePicker:(id)sender 时，将调用来自TakePhotoViewController 的-(void)didCancelCamera。

但是，不知何故，didCancelCamera 中的代码导致再次调用 TakePhotoViewController 的 viewDidAppear 方法并重新打开图像选择器。

不知道为什么

[[self.overlayViewController.imagePickerController presentingViewController] dismissViewControllerAnimated:NO completion:^ {
        [self performSegueWithIdentifier:@"fromTakeToWelcome" sender:self];
    }];

导致再次调用该视图 (TakePhoto) 的 viewDidAppear 方法。

希望对大家有所帮助

【讨论】：