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So will come back again in this exercise you are supposed to rewrite the code we did in our previous

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lesson which was swift and redo it again you know Objective C.

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Now this is one of those exercises that they really encourage you to attempt it on your own simply because

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doing delegation even though in terms of the concept is exactly the same thing.

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Blade has some of the stuff that you know you may not really grasp in the very first attempt and doing

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them once in Objective C is going to show you some you know some more insights into using them and coding

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it.

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So I really encourage you to actually try it on your own.

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I'm going to pause the video now for a few seconds.

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This is the time for you to pause entirely and try it on your own and then come back to the code and

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the solution that I have and show to compare it with what you have the.

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So let's get started.

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In the interest of saving time I've actually made parts of my application already I've made my interface

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builder the Baden's I've made my segue.

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I have connected all these different you know outlets.

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So in my view controller I have a label received message but I have a call to action in my view contorted

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and I have to program the body of this method in my view controller.

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I have the textfield and I have a go back action.

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And of course I have to program the body of this one.

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So let's first get the things we know out of the way.

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In my view toward that end I'm going to go ahead and say import the green of your controller and you

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might go to with green action.

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I'm going to say self performs Segway performs Segway with identifier on the identifier.

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I gave it was called Green Segway ID.

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I have no senders.

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So that's one part of the problem.

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The other part obviously is the preparation some going to say void prepare for Segway.

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And again you could check for the sake of the identifier or you could skip it just like what I'm doing.

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I'm going to say green View Controller Green an instance is going to be Segway our destination view

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controller and that's about that.

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So so far we managed to prepare our getting in stance and we also got our Segway to be performed.

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Now I'm going to go to Green view controller on the go back action.

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I'm going to get emesis drink let's say text or send that is going to be the name of my textfield the

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DOT to text.

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Obviously the value in it I'm going to store it and then I'm going to say self this mystery controller

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animated.

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True.

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And I don't want to do anything.

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It's completion.

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Perfect.

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So we got this far and by now we should be able to launch an application.

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It should be you know managed to go from one viewpoint or to the other one and do the basic stuff just

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the way that we expected it in here.

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I could go ahead and say go to Green go perfect.

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So the next thing we need to do is we need to add the protocol to our application so to do that we can

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either introduce your protocol inside the body of one of your data files or you could do it the way

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I personally like to do and that's adding in new data h find someone to say command and here is a header

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file and this other file I'm going to call it put a can remember protocols.

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They don't have any logic so all they have is actually the body of their declaration and because their

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declaration they are like interfaces so they are data aitches header files.

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So I'm actually going to say import and I have to import the foundations simply because without the

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foundation there isn't really much we can do.

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The next thing is say at protocol and my protocol is going to be called sending mass sage protocol and

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this thing that you see in here it essentially means that the sending masses for the core conforms to

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this object itself.

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This is actually an optional thing.

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You could if you wanted to remove it and the only method I have in it is this voice.

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And it sends a just call send and the send is actually a and has a string on that and assisting is called

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message just like what we had last time.

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Now as you might very well remember from our swift example one of these two view controllers view controller

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that h n m not degree in one.

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They have to conform to that protocol.

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And the other one should use the protocol.

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So first this can conform to it.

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And when I was at that stage I'm going to say let's first import whether re-importing protocol import

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protocol.

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And then my view controller is a subclass of viewpoint.

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And it also conforms to sending message protocol.

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Now that I have it conforming to a sending message protocol I have to be including those methods which

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is essentially this one in the body of my implementation which is in my data and so it might that ominous

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one is going to give me an error in itself.

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I have to add that when I go in here and say well this one is in here.

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So whenever somebody calls send from the delegates who are delegating to you being called the view controller

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this function should run and if this function does run I'm going to say received Laymon that text should

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become whatever we receive just like the last time that we had done that.

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Now the other thing that we had to do was we had to go through Grandview contorted and say hey this

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one is using the Send the message protocol as a very old outcome but to say at property and that property

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is going to be non atomic and is going to be of the type i.e. the Veach does conform to what does it

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conform to sending message protocol which I have to import it.

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I'm going to say import protocols and it is going to be sending Nassir protocol and I'm calling delegates.

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So what is this.

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This line is essentially the one that we had in the swift which was our delegate of the times sending

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message delegate that was that and we have it in here as a property which is this what exactly.

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And that property since we don't know its type we're going up with doesn't the objective.

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Are saying that this is an idea which does conform to this.

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It is called of course delegate and it is non-atomic.

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We'll talk more about the atomic non-atomic and retain and sign at the end of this section.

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So keep this one for now the way it is now.

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I have that property.

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And the next thing I could do is I could go to my viewpoint or that am saying when you make the union

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stance do you agree any stance that delegates to self so delegate tasks from this one to here.

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Here being my view controller.

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And finally in my viewpoint for that am I'm going to go ahead and say every time you're going back do

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self delegate send what you want to send.

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I want to send this particular text.

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This is exactly identical to what we did for swithe is exactly the same thing but the return objective

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c when we're going back we get the delegate and we use its method.

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We send the something doesn't matter what that thing is.

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It is the one in the text which you know View Controller Vicki form to this particular protocol which

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means it's methods most notably this one should be activated in here it should have a function body

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in here the body of it is get the message up within the label.

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And finally in here we are saying that when you're preparing for say what you want to do is you want

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to say this new one the new instance then it gets to here being the View Controller.

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So I'll go around this and if all goes well go to Green Hello from green.

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And it says hello from doing.

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And that's about that.

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Using protocols and delegation patterns in both the iOS 4 of its swift and I was with Objective-C.

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Let's keep that in mind in the next lesson.

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We're going to move into something that is using an existing delegation from one of four athletes.