ios - presentViewController 后黑屏

Question

我有一个名为 SecondViewController 的 UIViewController，它使用 UIImagePickerController 加载照片库。当我选择一张照片时，它应该显示另一个名为 PhotoViewController 的 View Controller 。为了将图像从 SecondViewController 传递到 PhotoViewController，我使用了单例。这是代码:

第二 View Controller :

@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];
}

照片 View Controller :

@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;
}

所以当我选择一张图片时，应用程序在调试区域显示黑屏，没有错误。怎么了？

P.S.: 我正在使用 Storyboard 和 ARC

Answer 1

注意事项:

• 如果 PhotoViewController 是在 Storyboard中设计的，则您在 sharedInstance 中实例化它的方式不正确。它只是创建一个普通的 PhotoViewController，没有创建任何 Interface Builder 对象。
  • 此处更好的方法是将 SecondViewController 和 PhotoViewController 的场景与 Storyboard 中的手动模式转场连接起来。然后在 didFinishPickingMediaWithInfo 中的 SecondViewController 中，在 PhotoViewController 上设置照片并手动触发 segue。
PhotoViewController 的
• viewDidLoad 只会被第一个调用它出现的时间，所以它不是设置照片的正确位置随后的发射。考虑 viewWillAppear
• 确认 photoView 连接在属性和接口(interface)之间 Storyboard中的构建器元素