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iOS @protocol

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Branda22

macrumors newbie
Original poster
Jun 17, 2013
25
0
Chicago, IL
I'm confused as to the purpose of using protocols.

Is a protocol useful when you want an object to conform to a required set of methods? Let's say I have a class that I want to require certain methods to be implemented, I would then use a protocol to list out the required and optional methods?
 
T

truehybridx

macrumors member
Dec 6, 2010
86
0
Branda22 said:
I'm confused as to the purpose of using protocols.

Is a protocol useful when you want an object to conform to a required set of methods? Let's say I have a class that I want to require certain methods to be implemented, I would then use a protocol to list out the required and optional methods?
Click to expand...

Yup, thats ultimately a reason for doing @protocol... Think of <UITableViewDelegate>, it's a protocol that defines methods your object needs to implement, because the tableView will call those on that object
 
ArtOfWarfare

ArtOfWarfare

macrumors G3
Nov 26, 2007
9,560
6,059
Today I used them because I had a root table view that leads to a variety of other types of views. No matter which type of view it led to, I wanted to pass the same thing to it from my root view. So I wrote a protocol in my root view's header that defined a property, then I had each of my other views conform to the protocol so that in my prepare for segue method I could just cast the destination view controller to an id<protocol> and utilize the property I had defined as being part of the protocol.

Protocols are a way of just saying, I'm not sure what exactly you are, but whatever you are, I want you to have this set of methods. It allows you to keep your program modular and easy to expand. IE, I can easily add other sub view types and all I have to do is say they conform to that protocol.
 
Duncan C

Duncan C

macrumors 6502a
Jan 21, 2008
853
0
Northern Virginia
ArtOfWarfare said:
Today I used them because I had a root table view that leads to a variety of other types of views. No matter which type of view it led to, I wanted to pass the same thing to it from my root view. So I wrote a protocol in my root view's header that defined a property, then I had each of my other views conform to the protocol so that in my prepare for segue method I could just cast the destination view controller to an id<protocol> and utilize the property I had defined as being part of the protocol.

Protocols are a way of just saying, I'm not sure what exactly you are, but whatever you are, I want you to have this set of methods. It allows you to keep your program modular and easy to expand. IE, I can easily add other sub view types and all I have to do is say they conform to that protocol.
Click to expand...

Protocols also serve as an alternative to multiple inheritance, which Objective-C does not support.

If you have 3 different classes with different ancestry that you all want to teach a common set of behaviors to, and want to be able to create a shared interface to, you can make them all conform to a protocol.

In C++, which DOES support multiple inheritance, you might solve the same problem by creating a new base class and then creating subclasses of all 3 classes that inherit from both their class and the new class.

A protocol is like a specific technical jargon that objects agree to speak with each other. As ArtOf
 
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