What control to use to capture image from camera and show on ui as thumbnail with events xamarin ios - swift

Question

I have created a view like this in my xamarin iOS mobile project.
User will be able to click on the capture images button to take a picture and set the image property of the image view. I would like to know how can i allow the user longpress a image (after it has been captured) and popup a message box to delete the image.
I have tried what Sameer has suggested in his comment like so in my ViewDidLoad
var gestureRecognizer = new UILongPressGestureRecognizer();
gestureRecognizer.AddTarget(() => ButtonLongPressed(gestureRecognizer));
img1.AddGestureRecognizer(gestureRecognizer);
img2.AddGestureRecognizer(gestureRecognizer);
When i click and hold on the image nothing happens. I have added these image views via the designer.
After a little more research and using the comment from #Junior Jiang - MSFT. I have made a bit progress but i would like to know which UIImage view has been clicked.
Heres my current code:
public JobImagesViewController(Job passedInCurrentJob) : base("JobImagesViewController", null)
{
currentJob = passedInCurrentJob;
uIImageViews = new List<UIImageView>();
}
public override void ViewDidLoad()
{
base.ViewDidLoad();
uIImageViews.Add(img1);
uIImageViews.Add(img2);
uIImageViews.Add(img3);
uIImageViews.Add(img4);
uIImageViews.Add(img5);
uIImageViews.Add(img6);
uIImageViews.Add(img7);
uIImageViews.Add(img8);
uIImageViews.Add(img9);
uIImageViews.Add(img10);
InitialiseImageGrid();
// Add a Save button to the navigation bar
this.NavigationItem.SetRightBarButtonItem(
new UIBarButtonItem("Save", UIBarButtonItemStyle.Done, (sender, args) =>
{
//TODO if else block with all logic to check if there are images etc.
//TODO prompt user and ask if they would like to save images.
UIAlertView alert = new UIAlertView("Save Images?", "Save images against the Job?", null, "Yes", new string[] { "No" });
alert.Clicked += (s, e) =>
{
if (e.ButtonIndex == 0) // Yes clicked
{
SaveJobImages();
}
};
alert.Show();
}), true);
}
[Export("ImageLongPressed:")]
public void ImageLongPressed(UILongPressGestureRecognizer gestureRecognizer)
{
if (gestureRecognizer.State != UIGestureRecognizerState.Began)
{
return;
// Needed because selector is executed twice, because Long-press gestures are continuous
}
// Perform action of opening the dialog to select/take a picture, replacing the ? image with the new image
UIAlertView alert = new UIAlertView("Delete this image ?" , "Are you sure you want to delete this image?", null, "Yes", new string[] { "No" });
alert.Clicked += (s, e) =>
{
if (e.ButtonIndex == 0) // 'Accept' clicked
{
// TODO how to get the image which has been clicked??
}
};
alert.Show();
}
private void InitialiseImageGrid()
{
_imageList = DataAccess.GetImages(currentJob.jobAddressID);
var imageBytes = _imageList.Select(x => x.ImageBytes).ToList();
var gestureRecognizer = new UILongPressGestureRecognizer(this, new ObjCRuntime.Selector("ImageLongPressed:"));
gestureRecognizer.AddTarget(() => ImageLongPressed(gestureRecognizer));
// Populate the image views.
// TODO need to find a way to assign it to every imageview on the view without looping maybe linq???
int i = 0;
foreach (var item in imageBytes)
{
var imagedata = NSData.FromArray(item);
var img = UIImage.LoadFromData(imagedata);
if (uIImageViews != null && uIImageViews.Count > i)
{
uIImageViews[i].UserInteractionEnabled = true;
uIImageViews[i].AddGestureRecognizer(gestureRecognizer);
uIImageViews[i].AddGestureRecognizer(gestureRecognizer);
uIImageViews[i].Image = img;
}
i++;
}

Answer 1

It depends on how you are creating your view, are you using a XIB with all the images on there as buttons with images, and IBActions connected to those buttons. just make the sender a UILongPressGestureRecognizer.
If you are doing it through code, then in your ViewDidLoad you want to set your buttons to have an initial ? (or Image Needed) background image and then you add the UILongPress GestureRecognizer to each on of them. So if you had one button, you would do this:
public override void ViewDidLoad ()
{
// Perform any additional setup after loading the view
UIButton button = new UIButton (new System.Drawing.RectangleF(100, 100, 100, 30));
button.SetBackgroundImage ("imageNeeded", UIControlState.Normal);
var gestureRecognizer = new UILongPressGestureRecognizer ();
gestureRecognizer.AddTarget(() => this.ButtonLongPressed(gestureRecognizer));
button.AddGestureRecognizer(gestureRecognizer);
this.View.Add (button);
}
public void ButtonLongPressed(UILongPressGestureRecognizer gestureRecognizer)
{
if (gestureRecognizer.State != UIGestureRecognizerState.Began)
{
return;
// Needed because selector is executed twice, because Long-press gestures are continuous
}
// Perform action of opening the dialog to select/take a picture, replacing the ? image with the new image
}

Answer 2

If want to use UILongPressGestureRecognizer in UIImage, should set ImageView's UserInteractionEnabled be true.
As follow:
List<UIImageView> imageViews = new List<UIImageView>();
UIImage image = UIImage.FromFile("off.png");
ImageViewOne.Image = image;
ImageViewOne.Tag = 1;
ImageViewTwo.Image = image;
ImageViewTwo.Tag = 2;
imageViews.Add(ImageViewOne);
imageViews.Add(ImageViewTwo);
foreach (var imageview in imageViews)
{
imageview.UserInteractionEnabled = true;
UILongPressGestureRecognizer uITapGestureRecognizer = new UILongPressGestureRecognizer();
uITapGestureRecognizer.AddTarget(() => { Console.WriteLine("You choose View " + imageview.Tag); });
imageview.AddGestureRecognizer(uITapGestureRecognizer);
}
Here is official document from Apple.