Ios presentViewController后的黑屏

我得到了一个名为SecondViewController的UIViewController，它使用UIImagePickerController加载照片库。当我选择照片时，它应该显示另一个名为PhotoViewController的视图控制器。要将图像从SecondViewController传递到PhotoViewController，我使用单例。代码如下：

第二视图控制器：

@property (strong,nonatomic) UIImagePickerController *libraryPicker;
@property (strong,nonatomic) UIImage *chosenImage;
@property (strong,nonatomic) PhotoViewController *controller;

- (void)viewDidLoad
{
        controller = [PhotoViewController sharedInstance];
        libraryPicker = [[UIImagePickerController alloc] init];
        libraryPicker.delegate = self;
        libraryPicker.allowsEditing = NO;
        libraryPicker.navigationBarHidden = NO;
        libraryPicker.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;
        [self presentViewController:libraryPicker animated:YES completion:nil];
}

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    chosenImage = [info objectForKey:UIImagePickerControllerOriginalImage];
    controller.photo = chosenImage;
    [libraryPicker dismissViewControllerAnimated:NO completion:nil];
    [self presentViewController:controller animated:YES completion:nil];
}

@property (strong,readwrite) IBOutlet UIImageView *photoView;
@property (strong,readwrite) UIImage *photo;
+ (PhotoViewController *)sharedInstance;

static PhotoViewController *_self;
+ (PhotoViewController*)sharedInstance
{
    if (_self == nil) {
        _self = [[super alloc] init];
    }
    return _self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    photoView.image = photo;
}

PhotoViewController：

@property (strong,nonatomic) UIImagePickerController *libraryPicker;
@property (strong,nonatomic) UIImage *chosenImage;
@property (strong,nonatomic) PhotoViewController *controller;

- (void)viewDidLoad
{
        controller = [PhotoViewController sharedInstance];
        libraryPicker = [[UIImagePickerController alloc] init];
        libraryPicker.delegate = self;
        libraryPicker.allowsEditing = NO;
        libraryPicker.navigationBarHidden = NO;
        libraryPicker.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;
        [self presentViewController:libraryPicker animated:YES completion:nil];
}

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    chosenImage = [info objectForKey:UIImagePickerControllerOriginalImage];
    controller.photo = chosenImage;
    [libraryPicker dismissViewControllerAnimated:NO completion:nil];
    [self presentViewController:controller animated:YES completion:nil];
}

@property (strong,readwrite) IBOutlet UIImageView *photoView;
@property (strong,readwrite) UIImage *photo;
+ (PhotoViewController *)sharedInstance;

static PhotoViewController *_self;
+ (PhotoViewController*)sharedInstance
{
    if (_self == nil) {
        _self = [[super alloc] init];
    }
    return _self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view.
    photoView.image = photo;
}

因此，当我选择一张图片时，应用程序会在调试区域显示一个没有错误的黑屏。怎么了

附言：我正在使用故事板和ARC来记录一些事情：

• 如果在情节提要中设计了

  PhotoViewController

  ，则在

  sharedInstance

  中实例化它的方式不正确。它只创建一个普通的

  PhotoViewController

  ，没有创建任何Interface Builder对象。
  • 在这里，更好的方法是将

    SecondViewController

    和

    PhotoViewController

    的场景与故事板中的手动模式序列连接起来。然后，在

    中的
    SecondViewController
    中，使用信息完成PickingMediaWithInfo

    ，在PhotoViewController上设置照片并手动触发segue

• PhotoViewController

  的

  viewDidLoad

  将只调用第一个 时间到了，所以这不是拍摄照片的合适地点 随后的发射。考虑<代码> VIEW会出现
• 确认属性和接口之间已连接

  photoView

  情节提要中的生成器元素