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In business and we're going to see an actual delegation happening in a real US application what we are

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going to do is this we are going to go in Iowa with Tuvia controllers from what you can do or navigate

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to the next one in the next one.

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We will have a text field.

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We enter a value and we hit the back button but when we come back for the very first view controller

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we will see the masses we entered in the sack and The View Controller is essentially going to be a way

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for us to send a message from second to regular First the controller then the back.

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Why then is being pressed so let's see how are we going to do that.

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And when I go to school I'm going to start a new project this new project is going to be I was single

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view applications swift and I'm going to call it delegation.

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I guess I my delegation I was going to do some stuff that we already know how to do them like you know

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adding in new View Controller and everything.

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So let's say View Controller is our very first controller and I'm going to have myself a second view

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controller.

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I'm going to call this one our let's call it green view controller because I'm going to make it's by

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gone green obviously.

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So in the storyboard I have the default one which is essentially the The View control outlet.

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I'm going to have another one and this is a good time for us to you know repeat some of the older topics

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things that we covered in the previous sections.

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This is the one that's going to be green so I'm going to make it's going to become some sort of figurine

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and it's in that identity in a spectrum.

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But I call it to be the green View Controller.

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So so far we have to view controllers.

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I'm of course going to have a segue between this one too that one of the type Schull.

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Well I'm going to call this fun Green segue.

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Green segue Heidi.

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OK.

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So we've got all of these taken care of.

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Well next thing is I need a button to navigate to the green View Controller.

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So I'm going to add a button and this button since it's going to take us to the green one is going to

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be green.

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And it says in maybe Black says gold or green and I'm not going to make a Segway for it in here.

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We're going to make it programmatically.

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And I'm also going to have a label in here which is essentially the message that we receive.

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All right.

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So this one I'm going to say actually it's my gun.

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I'm going to leave it as dark grey by this text.

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I'm going to make it daring because this is the message we received from the other side.

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And currently it says message.

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Is there something that I want perfect.

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So we got that now in the other of your control.

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I'm going to have to have a pardon.

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And that's what it is up here.

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And that button says with a white background that is you know indicative of the view that is going to

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go back to.

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It says Go back and that's about that.

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It says Go back in black and then I have a text field that I can enter a value in it.

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So that's a text with my text which is a little bit larger than I like it without borders.

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I like it to be a little bit larger.

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I can say it's back.

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These are all very very light gray and text and it is there's a message perfect of what everything they

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need in terms of the outlets.

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Now I have to connect them to their respective of things in the coding area to the outlets as well as

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our actions.

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So in here on when our Lord my assistant editor I'm going to say for the first few controller I'm going

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to need these outlets I need.

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And an action that says action go to Green action.

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And I also need a label that says receive the message label.

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And that's about that.

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I've got the label and I got an action that I'm going to go to the other one to the green one and the

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green one and they have to do some cleanup.

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I'm going to do all of that right now.

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And in the green one I to have an A go back action.

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So that's going to be a go bag action.

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You know as always and I also have a text field that says not sage text.

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So I've got a text with a body action.

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Everything is ready.

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So now let's go ahead and see how we want to do how we can pass that on.

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The first thing I want to do is this every time that I press the button in they go to Green action.

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I want to say this I want to say self guard perform saying they identifier and here is the identifier

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that I need a thing I called it green.

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Identifier.

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Yes.

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Green segue.

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So that's the name for it green segue ID understand.

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Isn't it.

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Now here's one thing we did that when we go to the game in action we performed the Segway.

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If you recall we also have to prepare for that signee and he has hongbin do that.

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And when I say prepare for a Segway and in an ideal world if you want to be super careful about everything

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you have to say if Segway DOD identifier is blah blah blah.

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I don't really I'm not going to do that simply because I know I only have one Segway.

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So the only thing I'm going to do is that I'm going to say that I'm going to call it green in Staats

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is going to be sick of a destination.

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Now keep in mind the destination is a you view controller but they want it to be as green if you can

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it.

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I want it to be of this type.

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I want it to be forced as you know inferred as a green view controller.

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So so far be prepared even though we are not doing anything in here just yet and we perform the same

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way.

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Let's see what we see in the green view controller in here.

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We have a text field in here that we haven't done anything and we have a function that takes us back.

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This first thing with the function that takes us about it says self that this is true and that's about

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that.

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And don't do anything at completion.

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So that's one part of it and another thing I'm going to do is I'm going to say let's text to send.

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Is going to be message text field that dot text.

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So let's get the text in the message text.

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We don't we have to do something with it.

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We have to do something.

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I just don't know what that thing is.

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So if all goes well by now we should be able to navigate back and forth.

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So let's go ahead and run this application even though some variables are not being used just yet they're

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just sitting there on their own for not doing anything with them but this application essentially does

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work and takes us from one of your contorted to the other one where there is a text field that we can

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enter values and where we can hit the back within.

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But obviously nothing gets communicated between our two controllers.

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So once I have my eye out I'm going to call this file to be a protocol create I know I have this protocol

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that I'm going to say it is actually a protocol it's called sending a message delegates and that's about

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that it of one method called function send me which essentially gets a message of to tie a string and

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that's about that's all it does.

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So here in my view control the very first view controller I'm going to say this class view controller

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conforms to you eye view controller and also sending the message delegate.

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So it conforms to both of them.

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And now you get an error saying well if you want to conform to this you also have to give it that method

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that method is called.

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I forgot this cause I'm just going to add it in here.

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It says send a message.

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So it has to conform to this one.

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So what do you want to do whenever this function happens will come to this in a second.

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The other thing I want to do is this I want to go to my grave you can sort of just like the last time

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this is the guy who is going to be our sender.

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If you remember from our previous example this was for instance or a user.

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So I'm going to say well I have a valuable I'm going to call it the elegant which is of the type sending

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the message delegate.

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So I have this variable in green view controllers.

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So what do you want to do you want them to do this will they want them to do.

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When I pressed the go back action I want my delegate to call its message and I want to send this particular

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message text to send.

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So that's the text that I want to send through the delicate matter.

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Now who is going to receive this.

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On the other end The View Controller.

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This function has to receive it.

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What should it do was it received it.

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It has to put it in the received message Nevel the text as to be become message.

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Now there is one piece still missing and that is this function works well if we reset giving a message

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it puts it in our label.

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This one works well.

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It sends it to its delegate's.

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The only thing we don't know is the green view controller is delegating his tasks to which object.

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And that's something they haven't done yet.

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So if I go to my view controller and in here I'm gonna say green stance

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that delegate is going to be self.

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What it means is this it means the green stance is going to deligated tasks all of its tasks to self

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which is the view controller which does conform to send the message delegate.

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Which means if the any green stands delegate's its particular function call to send this class viewer

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response.

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So when the game view controller says in case you were going back there to get that send this message

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the one who is going to actually receive this message is going to be our view controller.

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This is because our warning is because we didn't change anything and well turn that into a constant

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and let's run our application one more time and see what do we get.

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And here's my simulator and I have go to Green and saying hello white go back I says hello once I go

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in here.

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I say Are you a fool sky.

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I don't know why I came up with that.

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I go back and it says beautiful sky.

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It sends a message to the other side.

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Let me quickly recap things that they made a big chunk of it doesn't really matter.

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So our view controller has a label has an action none of them Mandos performs a Segway.

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We know how that works.

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This part is a new thing.

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Prepare for Segway.

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It says get the Segway destination as Glenview controller and set its delegates to be here.

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Now Grangeville a controller has a delegate valuable in it which is of the type sending message delegate

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and seen sending message delegate also has that particular function whenever we call that one delegate

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to send somebody would be on the other side trying to receive these.

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In this case that it has to be the view controller the sky which does not conform to sending message

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and get either receives that one.

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So that's about that.

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We managed to successfully communicate between two objects of our differing classes.

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One of them conforming the other one using delegate valuable and let's move on doing the same thing

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once again as an exercise I will also do it at the end.

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In Objective-C.