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This article mainly explains "how to use the protocols in Objective OC". Interested friends may wish to have a look. The method introduced in this paper is simple, fast and practical. Let's let the editor take you to learn how to use protocols in Objective OC.

In fact, the protocols in OC are a bit like interfaces or abstract classes. The protocol in OC defines a series of methods, some of which must be implemented and some that do not need to be implemented.

The keyword that defines a protocol is @ protocol

For example:

@ protocol Ainy

-(void) Print

@ end

As above is a protocol, the name of the protocol is Ainy. A method is defined as-(void) Print. Note that the protocol is defined in the h file, for example:

How to implement this Ainy protocol: use parentheses, as follows

I have created a new Dog class, which inherits Animal, and needs to implement the protocol Ainy code as follows:

The implementation in Dog.m is as follows:

/ Dog.m// PartDemo//// Created by Apple on 2017 Apple 12 Apple / Copyright 2017. All rights reserved.//#import "Dog.h" @ implementation Dog@synthesize ID;- (void) Print {NSLog (@ "Xiao Huang");} @ end

Of course, it is possible to define the Aonaufly protocol in Animal, how to display both Ainy and Aonaufly protocols?

@ interface Dog: for Animal, separated

The question is, how to define methods that do not need to be implemented and how to define methods that must be implemented

@ optional defines methods that do not necessarily need to be implemented (followed by all methods)

@ required defines methods that must be implemented (all subsequent methods)

How do we know that this class implements the Ainy protocol?

Id Object

If ([Object conformsToProtocol: @ protocol (Ainy)] = = YES) {

}

If you know that Object must have implemented the protocol Ainy, you can do this.

Id Object

Join Object to implement the protocol Ainy, how to know that Object implements the method Dance of Ainy, because Dance is a method that can be implemented without implementation

If ([Object respondsToSelector: @ selector (Dance)] = = YES) {

}

At this point, I believe you have a deeper understanding of "how to use protocols in Objective OC". You might as well do it in practice. Here is the website, more related content can enter the relevant channels to inquire, follow us, continue to learn!

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