ios - 关闭应用程序后，从相机拍摄的照片不会出现在 ImageView 中

Question

我有两个，我的看法。1. ImageView -img2. Uibutton-拍照该应用程序的目的是在 ImageView 上显示图像。当我点击按钮时，我有两个选择。或者拍个相册，或者拍个照相相机。当我从相册中拍照时，图像保存在我的应用程序中并列在 ImageView 中，当我关闭将在后台运行的应用程序并返回到应用程序时，图像仍然存在。问题出在相机上，当相机列在 imageview 上并保存在设备的相册中时，我会拍照。但是当我关闭将在后台运行的应用程序并返回到该应用程序时，图像并没有驻留在 imageview 上，为什么？

这是我的完整代码:

-(void)viewDidLoad {
    [super viewDidLoad];


    NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];

    NSURL *selectedImageURL = [NSURL URLWithString:[userDefaults objectForKey:@"selectedImageURL"]];
    if (selectedImageURL)
    {
        [self getImageFromAssetsAtURL:selectedImageURL completion:^(UIImage *image, NSError *error)
         {
             if (!error && image)
             {
                 self.img.image = image;
             }
         }];
    }
    // Creating a Circular Profile Image.
    self.img.layer.cornerRadius = self.img.frame.size.width / 2.0;
    self.img.clipsToBounds = YES;

    // Adding Border to image.
    self.img.layer.borderWidth = 6.0;
    self.img.layer.borderColor = [UIColor blackColor].CGColor;
}

-(void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

-(IBAction)takePic:(id)sender {

    // ALERT SHEET.
    UIAlertController *alert = [UIAlertController alertControllerWithTitle:nil message:nil preferredStyle:UIAlertControllerStyleActionSheet];

    //CAMERA
    UIAlertAction *openCamrea = [UIAlertAction actionWithTitle:@"צלם" style:UIAlertActionStyleDefault handler:^(UIAlertAction * action)
    {
        // If device has no camera.
        if (![UIImagePickerController isSourceTypeAvailable:UIImagePickerControllerSourceTypeCamera])
        {
            UIAlertController *alertNoCamera = [UIAlertController alertControllerWithTitle:@"Error" message:@"Device has no camera" preferredStyle:UIAlertControllerStyleAlert];
            UIAlertAction *ok = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction * action){}];
            [alertNoCamera addAction:ok];
            [self presentViewController:alertNoCamera animated:YES completion:nil];
        }
        else// if  have a camera.
        {
           UIImagePickerController *picker = [[UIImagePickerController alloc] init];
           picker.delegate = self;
           picker.allowsEditing = YES;
           picker.sourceType = UIImagePickerControllerSourceTypeCamera;


           [self presentViewController:picker animated:YES completion:NULL];
        }
    }];
    // GALLERY
    UIAlertAction *openGallery = [UIAlertAction actionWithTitle:@"גלריה" style:UIAlertActionStyleDefault handler:^(UIAlertAction * action)
    {
        UIImagePickerController *picker = [[UIImagePickerController alloc] init];
        picker.delegate = self;
        picker.allowsEditing = YES;
        picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;

        [self presentViewController:picker animated:YES completion:NULL];
    }];

    [alert addAction:openCamrea];
    [alert addAction:openGallery];

    [self presentViewController:alert animated:YES completion:nil];
}


-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info
{
    UIImage *image = info[UIImagePickerControllerOriginalImage];
    NSURL *selectedImageURL = info[UIImagePickerControllerReferenceURL];

    if(picker.sourceType == UIImagePickerControllerSourceTypeCamera)
    {
        UIImageWriteToSavedPhotosAlbum(image, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);
        // set image
        self.img.image = image;
    }
    else{
        self.img.image = image;
    }
    // save image url
    NSUserDefaults *userDefaults = [NSUserDefaults standardUserDefaults];
    [userDefaults setObject:selectedImageURL.absoluteString forKey:@"selectedImageURL"];
    [userDefaults synchronize];

    // set image
    self.img.image = image;

    // dismiss
    [self dismissViewControllerAnimated:YES completion:nil];

}
-(void)imagePickerControllerDidCancel:(UIImagePickerController *)picker {
    [picker dismissViewControllerAnimated:YES completion:NULL];
}
// chkeing if image save on album ot not.
- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo
{
    UIAlertAction *ok = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction * action){}];
    if (error) // Unable to save the image
    {
        UIAlertController *alertErorr = [UIAlertController alertControllerWithTitle:@"Erorr" message:@"Unable to save image to Photo Album." preferredStyle:UIAlertControllerStyleAlert];
        [alertErorr addAction:ok];
        [self presentViewController:alertErorr animated:YES completion:nil];
    }
    else // All is well
    {
        UIAlertController *alertSuccess = [UIAlertController alertControllerWithTitle:@"Success" message:@"Image saved to Photo Album." preferredStyle:UIAlertControllerStyleAlert];
        [alertSuccess addAction:ok];

        self.img.image=image;
        [self presentViewController:alertSuccess animated:YES completion:nil];
    }
    [self dismissViewControllerAnimated:YES completion:NULL];
}
-(void)getImageFromAssetsAtURL:(NSURL *)imageURL completion:(void (^) (UIImage *, NSError *))completion
{
    PHFetchResult *result = [PHAsset fetchAssetsWithALAssetURLs:@[imageURL] options:nil];
    if (result.count == 1) {
        PHAsset *asset = result.firstObject;
        [[PHImageManager defaultManager] requestImageDataForAsset:asset options:nil resultHandler:^(NSData * _Nullable imageData, NSString * _Nullable dataUTI, UIImageOrientation orientation, NSDictionary * _Nullable info) {
            UIImage *selectedImage = [UIImage imageWithData:imageData];
            completion(selectedImage, nil);}];
    } else {
        completion(nil, nil);
    }
}

@end

Answer 1

最好的方法是将图像保存到您的应用程序沙箱(文档目录)。通常我不建议在 NSUserDefaults 中保存图像，因为 NSUserDefaults 应该用于存储小设置而不是原始图像数据。

准备好图像后，将其保存在应用程序文档文件夹中。您稍后可以从保存的路径中删除图像!!!

您可以在 NSUserDefaults 中存储图像路径，但不能存储图像!!!

保存图片:

将此代码放在didFinishPickingMediaWithInfo 方法中:

如果图像在 UIImageJPEGRepresentation 中使用 .jpeg 扩展名，如果它在 UIImagePNGRepresentation 中使用 .png 扩展名

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *filePath = [NSString stringWithFormat:@"%@/%@", documentsDirectory, @"myImage.png"];
NSLog(@"filePath %@", filePath);
    NSError *error;
[image writeToFile:filePath atomically:NO];

取回图像:

    NSArray *arrayPaths =
    NSSearchPathForDirectoriesInDomains(
                                        NSDocumentDirectory,
                                        NSUserDomainMask,
                                        YES);
    NSString *path = [arrayPaths objectAtIndex:0];
    NSString* fileName = [path stringByAppendingPathComponent:@"myImage.png"];

  UIImage *image=[UIImage imageWithContentsOfFile:fileName];