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，它应该呈现另一个名为PhotoViewController的视图控制器。要将图像从SecondViewController传递到PhotoViewController，我使用单例。这是代码：

SecondViewController：

@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];
}

PhotoViewController：

@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，当我选择一张照片时，该应用程序在调试区域显示黑屏而没有错误。怎么了？

P.S。：我正在使用Storyboard和ARC

Answer 1

要注意事项：

如果在故事板中设计了PhotoViewController，那么您在sharedInstance中实例化它的方式是不正确的。它只创建一个没有创建Interface Builder对象的普通PhotoViewController。
- 这里更好的方法是将SecondViewController和PhotoViewController的场景与故事板中的手动模态segue联系起来。然后在SecondViewController didFinishPickingMediaWithInfo中，在PhotoViewController上设置照片并手动触发segue。
viewDidLoad PhotoViewController只会被称为第一个它呈现的时间，因此它不是设置照片的正确位置随后的发布。考虑viewWillAppear
确认属性和接口之间已连接photoView 故事板中的Builder元素

presentViewController之后的黑屏

1 个答案: