How to create a protocol with methods that are optional?

Question

I noticed methods marked optional in several protocols defined in the iPhone SDK, such as the UIActionSheetDelegate protocol for example.

How can I defi

Answer 1

Protocols act the same as abstract classes, so the @optional keyword defines those methods that are optional for implementation.

So, in the code, someMethod1, someMethod2 and someMethod4 are required methods (must be implemented). someMethod3 is optional - if we didn't implement this method, the compiler will not throw any warnings.

@protocol myPrtocol

-(void)someMethod1:(id)someArgument;
-(void)someMethod2:(id)someArugument;

@optional

-(void)someMethod3:(id)someArgument;

@required //by default

-(void)someMethod4:(id)someArgument;

@end

// sampleClass.m
@interface sampleClass : someSuperClass 
//...
@end