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Everyone welcome back Johnny be here with Stopes dot com.

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And in this lesson we are going to delete some comments.

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All right.

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So the last lesson we worked in our thoughts and comments cells to be able to add protocols and delegates

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so that we can inform our main view controllers when we have tapped on one of our option menu images.

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Right.

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So now we have our delegate functions here comment options tapped and do we want to have happen if we

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check out our mock up.

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Then it looks like we have an alert you pop up with the ability to delete the comment later on we're

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also going to add the functionality to edit the comment.

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But first we're going to look at the delete.

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All right so let's go ahead and let's do this.

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So I'm not going to cut this because I don't like these functions being up here at the top.

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And put this under our view did disappear right here.

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OK.

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All right.

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We need to add an alert.

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So we're going to let alert equal you are high alert controller and will initialize it here.

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So we're going to set the title to it.

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Hope needs to be a string added comment.

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The message will be something like you can delete or edit.

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And the preferred style is going to be that action sheet.

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All right now we need to create our actions so we're going to start out with just the two.

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We're going to have an add delete action and cancel action.

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It's going to say let delete action call a UI alert action initialize it with a title and the title

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is going to be delete comment and the style is going to be that default

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and then for our handlers are going to give us a completion handlers we just press enter and say action

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in code.

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All right and this is where we're going to delete the comment.

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OK.

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But we'll get right back to that and close this bottom pain.

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And I'm going to create the edit action right now even though we're not going to work on it yet.

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But I will say let action you call a UI alert action and initialize it.

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The title is going to be

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added comment.

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The style is not default.

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And the handler are going to say action and hopes and then we'll just remove that code block there.

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And then lastly the council is going to say let's cancel action equal alert action.

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Initialize it is going to be console.

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The style is.

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Cancel

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and the handler is nil and we go and then we just got to add these actions to our alert to say alert

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not add action and we want to add the to the read action then we want to add the added action.

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Now we want to add the Council action.

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And finally we just presented some say present.

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Here we go present view controller and the controller who is alert animated is true and completion is

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all right.

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And let's go ahead and test this just to make sure that this appears to run.

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All right let's pick one that has comments and then right click on this.

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There we go.

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All right.

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Very nice.

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So these don't do anything yet.

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So let's let's fix that.

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All right so to delete a comment or a document in Firestar it's actually pretty easy.

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All we got to do is get a reference to the document and call the delete function on it.

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So what we're going to do is we're going to say fire store which is our variable that we declare up

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here.

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Fire started off our store when say fire store data collection and we're just going to make our way

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down from collection to document to collection to document.

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And so if start ref that document and that path is here self Dot

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thought dot document ID and then we're going to go one layer deeper down to the comments collection

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so common start riff and then finally to the comment itself and we get that from our delegate function

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so comment DOD document ID and then we just call delete and we can call a completion here so delete

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and then get our completion and rename this to be error.

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And here in the code we can say if that error is equal to error.

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So we'll just do a check if there was an error and if there was an error and to close this bottom pain

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then we will debug printed and we'll say unable to delete comment and then we will print out the error

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localized description else then we will just say alert that dismiss animated is true and completion

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is no.

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And we need solve for it here.

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Self-taught fires aren't very good according to plan.

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When we click on this then we will delete that comment.

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I'm going to click on serious this thought that has four comments on it.

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Click here and click here and say delete.

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And boom it's gone.

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And but if we go back I emphasized how many comments it had.

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It had four comments and it still says that it has four comments.

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Well why is that.

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Well we are not updating the thought field for the number of comments.

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All right.

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So if you recall in the ad I thought VC when we added a or not the thought in the comments of VC when

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we added a comment we had to go through this whole thing with the run transaction to be able to first

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read the thought and get the thought.

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Then we had to extract the number of comments from it and then we had to run the transaction update.

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So that's kind of a pain but that's actually what we're going to have to do.

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Again here we're going to have to run a transaction to delete the comment.

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But first we are going to instead of incrementing the number of comments by one we are going to be decreasing

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the number of comments by one.

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All right.

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So I still want to show you this way because you know it is just useful for you to know multiple ways

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to do things.

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So this is how you would do it if you didn't have to worry about updating any other field if you are

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able to simply delete a document from fires or that you just get the reference to the document and call

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the delete function and you have the option of having or not having a completion handler.

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All right.

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So that's how you can do it.

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I'm going to just comment this out and then right down here we were going to do a transaction.

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Now that's a lot of code to write.

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And we already have it right here.

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So I'm just going to copy this transaction right here all the way down to here.

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Copy that and we're going to paste it right here.

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Close this bottom pane hand and we're going to modify it according to our needs.

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First off this needs to be self and all of this is the same we are getting the same document we are

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getting the same information the number of comments.

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The only thing that is different is that we are instead subtracting 1 from the number of comments.

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And but this part right here.

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This can all go away.

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We are not creating a new document and we are not setting new data.

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Instead what we are doing is you're calling a transaction not the leaked document.

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And all we've got to do is get the document reference which we already have right here so if we just

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copy from here a self of Firestorm collection we go down through the thoughts reference to the document

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to the Commons and then to the document here that's going to copy that and paste that right here so

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that we can get rid of any sort of comments that we need to.

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And there we go.

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And I'm just going to set this equal to a new very long I say let comment her equal and equal to this

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guy right here and then I'm going to pass in the document reference here comment breath save that.

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And here in the completion händler we're just going to say alert that dismiss animated is true and completion

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is now.

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All right so let's go ahead and run that.

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And while that's building I'll just run through what we have done once more.

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So we are running the transaction and remember in transactions you have to read and then right.

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So we go ahead and we do a read we go and fetch the thought document and that this comment is a child

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of.

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And then we get the number of comments from that data.

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We decrement the number of comments by one then we get a reference to the comment and we just call transaction

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delete document.

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All right so when we check this out.

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So now it's at 4.

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It should be 3.

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But if I delete this comment then we should see it be three because it has a decrease the number by

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one.

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This one has a comment.

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I'm going to delete it and it should now be had zero.

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And this one has a comment.

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I delete it then it's had zero.

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All right.

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Looks like it is working great for us.

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All right so that is how you can delete documents in the fire store if you don't need to worry about

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doing other reads and writes.

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Then you can call this a simpler function which is just getting a reference to the document and then

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calling delete if you need to handle it with along with other reads and writes then you're going to

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need to run it in a transaction which is similar.

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All you got to do is get the reference to the document and then call transaction delete document.

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All right so yeah super useful to know.

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Being able to delete data is you know something that you'll use very often in apps over again a lot

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of value out of this.

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And I will see you all in the next one where we start where we add the ability to edit the comment as

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well.

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All right.

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So I'll see you then.