In objective-C, a message processing method called: withobject:

Summary: In objective-C, the method used to call a function is message transmission. The difference between this method and a common function call is that you can transmit any message to an object at any time, instead of declaring these methods during compilation. Therefore, objective-C can deliver people and messages at runtime. First, we will introduce two methods.

In objective-C, the method used to call a function is "message transmission". The difference between this method and a common function call is that you can transmit any message to an object at any time, instead of declaring these methods during compilation. Therefore, objective-C can deliver people and messages at runtime.

 

First, we will introduce two methods: SEL and @ selector.

According to the official appleobjective-C Runtime reference documentation, the message passing function isIDObjc_msgsend (IDThereceiver,SelTheselector ,...)

Thereceiver indicates that the type of the message receiving object is ID, and the theselector indicates that the type of the message name is Sel. BottomCodeLet's take a look at how to generate a sel if a message is transmitted.

First, create a simple function.

-(Void) Foonoinputs {

Nslog (@ "Does nothing");

}

Then call it

[SelfPerformselector:@ Selector(Foonoinputs)];

The second test shows how to transmit parameters in a message.

We create a function with input parameters.

-(Void) Foooneiput :( nsstring *) first {

Nslog (@ "Logs % @", First );

}

Then call it

[SelfPerformselector:@ Selector(Foooneinput :) withobject:@ "First"];

Third test more parameters

-(Void) Foofirstinput :( nsstring *) First secondinput :( nsstring *) Second {

Nslog (@ "Logs % @ then % @", First, second );

}

Then call it

[SelfPerformselector:@ Selector(Foofirstinput: secondinput :) withobject:@ "First"Withobject:@ "Second"];

In the fourth experiment, how to create dynamic functions and then call them? We need to create a selector

SelMytestselector =@ Selector(Mytest :);

And the function we call is in another class.

-(Void) Abcwithaaa :(Nsnumber*) Number {

IntPrimarykey = [numberIntvalue];

Nslog("% I", Primarykey );

}

Methodforselectors* MFs = [Methodforselectors Alloc];

Nsarray* Arrays = [Nsarray Arraywithobjects:@ "AAA",@ "BBB",Nil];

For(Nsstring* ArrayInArrays ){

SelCustomselector =Nsselectorfromstring([NsstringStringwithformat:@ "Abcwith % @:", Array]);

MFs = [[Methodforselectors Alloc]Performselector: CustomselectorWithobject: 0];

}

Complete code:

@ ImplementationClassforselectors
-(Void) Foonoinputs {

Nslog (@ "Does nothing");

}

-(Void) Foooneiput :( nsstring *) first {

Nslog (@ "Logs % @", First );

}

-(Void) Foofirstinput :( nsstring *) First secondinput :( nsstring *) Second {

Nslog (@ "Logs % @ then % @", First, second );

}

 

-(Nsarray*) Abcwithaaa :(Nsnumber*) Number {

IntPrimarykey = [numberIntvalue];

Nslog("% I", Primarykey );

}

 

-(Void) Specified parameter hodsviaselectors {

[SelfPerformselector:@ Selector(Foonoinputs)];

[SelfPerformselector:@ Selector(Foooneinput :) withobject:@ "First"];

[SelfPerformselector:@ Selector(Foofirstinput: secondinput :) withobject:@ "First"Withobject:@ "Second"];

}

 

-(Void) Export mdynamicmethodsviaselectors {

Methodforselectors* MFs = [Methodforselectors Alloc];

Nsarray* Arrays = [Nsarray Arraywithobjects:@ "AAA",@ "BBB",Nil];

For(Nsstring* ArrayInArrays ){

SelCustomselector =Nsselectorfromstring([NsstringStringwithformat:@ "Abcwith % @:", Array]);

MFs = [[Methodforselectors Alloc]Performselector: CustomselectorWithobject: 0];

}

}

@ End

@ ImplementationMethodforselectors

-(Void) Abcwithaaa :(Nsnumber*) Number {

Nslog("% I", Number );

}

@ End