ios - ギャラリーから画像を選択して Imageview に配置できますが、後でその場所に保持できません

Question

ギャラリーから画像を選択して ImageView に配置することはできますが、後で viewController を変更するときに画像を保持できず、画像が消えます

-(IBAction)LibraryPicture
{
if([UIImagePickerController isSourceTypeAvailable:
    UIImagePickerControllerSourceTypePhotoLibrary])
{
    UIImagePickerController *picker= [[UIImagePickerController  alloc]init];
    picker.delegate = self;
    picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;
    [self presentModalViewController:picker animated:YES];

  }
  NSString  *pngPath = [NSHomeDirectory()  stringByAppendingPathComponent:@"Documents/Test.png"];
NSString  *jpgPath = [NSHomeDirectory() stringByAppendingPathComponent:@"Documents/Test.jpg"];


                }

 -(void)imagePickerController:(UIImagePickerController *)picker
  didFinishPickingImage : (UIImage *)image
             editingInfo:(NSDictionary *)editingInfo
{
 imageSelect.image = image;
 [picker dismissModalViewControllerAnimated:YES];

}


 -(void)imagePickerControllerDidCancel:(UIImagePickerController *)  picker
 {
[picker dismissModalViewControllerAnimated:YES];
 }

- (BOOL)shouldAutorotateToInterfaceOrientation:     (UIInterfaceOrientation)interfaceOrientation
 {

 return (interfaceOrientation == UIInterfaceOrientationPortrait);
 }
 - (IBAction)saveImage:(id)sender {

  NSLog(@"save image & Keep");
  }

この画像は、ユーザーが再度変更するまで維持する必要があります