如何将照片显示到另一个UIViewController中

Question

我想将相机拍摄的照片显示到另一个UIViewController中。 我尝试使用此代码段，但我认为我做错了什么，因为该照片未在第二个视图中显示：

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info {

    editedImage = (UIImage *) [info objectForKey:
                               UIImagePickerControllerEditedImage];
    originalImage = (UIImage *) [info objectForKey:
                                 UIImagePickerControllerOriginalImage];
    imageToSave = (editedImage!=nil ? editedImage : originalImage);


    // Check if the image was captured from the camera
    if (picker.sourceType == UIImagePickerControllerSourceTypeCamera) {
        // Save the image to the camera roll
        UIImageWriteToSavedPhotosAlbum(imageToSave, nil, nil, nil);
    }

    NSString *docspath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
    NSString *filepathJPG = [docspath stringByAppendingPathComponent:@"imagefile.jpg"];

    NSData *data = UIImageJPEGRepresentation(imageToSave, 0.8);
    BOOL result = [data writeToFile:filepathJPG atomically:YES];
    NSLog(@"Saved to %@? %@", filepathJPG, (result? @"YES": @"NO") );

    [picker dismissViewControllerAnimated:YES completion:nil];

    mainViewController *main = [[mainViewController alloc]init];
    [self.navigationController pushViewController:main animated:YES];
    main.myImag.image = imageToSave;
}

更新：

我更改为在第二个视图中使用情节提要：

-(void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender{
    if([[segue identifier] isEqualToString:@"idmain"]){
        mainViewController *main = (mainViewController *)[segue destinationViewController];
        main.myImag.image = imageToSave;
    }
}

在mainViewController中：

- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
    NSString *docspath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject];
    NSString *filepathJPG = [docspath stringByAppendingPathComponent:@"imagefile.jpg"];

    UIImage *img = [UIImage imageWithContentsOfFile: filepathJPG];
    if (img != nil) {
        // assign the image to the imageview,
        myImag.image = img;
    }
    else {
        NSLog(@"Image hasn't been created");
    }
}

但是当我按选择时，第二个视图控制器不会出现。

Answer 1

您要将照片保存在文档目录中，因此必须从文档目录访问它们

尝试

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
                                                         NSUserDomainMask, YES);

    NSString *documentsDirectory = [paths objectAtIndex:0];

    NSString* path = [documentsDirectory stringByAppendingPathComponent:imagefile.jpg];

    UIImage* image = [UIImage imageWithContentsOfFile:path];

通过此代码，您可以从文档目录中获取图像。

Answer 2

...假设您的imageToSave UIImage对象有效（首先），

代替
svc.myImag.image = imageToSave;
做这个

svc.currentImage = imageToSave;
//where currentImage is a UIImage synthesized property in mainViewController class

---

然后在mainViewController类的-viewDidLoad或-viewWillAppear中，
将currentImage设置到myImag UIImageView对象上。

只是：

//mainViewController
- (void)viewWillAppear {
    ...
    myImag.image = currentImage;
}

---

原因？？ ...
UIViewController的-initWithNibName：bundle：方法的iOS文档指出：

…您指定的nib文件不会立即加载。 它是在第一次访问视图控制器的视图时加载的。 如果要在加载nib文件后执行其他初始化，请重写viewDidLoad方法并在其中执行任务。 ...

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