IOS development-Introspective)

Basics:

Introspection is the inherent capability of objects. When running a program, objects can reveal their basic features based on requests.

You can send a message to an object to ask its own related questions. The object will provide you with an answer when the objective-C runs.

Introspection is an important coding tool that can make programs more efficient and robust.

All objects that inherit nsobjec have the following three methods:"

Iskindofclass: returns whether an object is that kind of class (inheritance defined DED)

Ismemberofclass: returns whether an object is that kind of class (no inheritance)

Respondstoselector: returns whether an object responds to a given Method

The parameter value of method 1 is [nsstring class], which is obtained by sending a class method named class to a class. For example:

If ([OBJ iskindofclass: [nsstring class]) {

Nsstring * s = [(nsstring *) OBJ stringbyappendingstring: @ "Xyzzy"];

}

 

The parameter value of method 3 is a selector, for example, @ selector (shoot ).

If the shoot method exists in the object, the response is true. For example:

If ([OBJ respondstoselector: @ selector (shoot)]) {

[OBJ shoot];

} Else if ([OBJ respondstoselector: @ selector (shootat :)]) {

[OBJ shootat: Target];

}

 

Describes a new type of Sel, which is the type of the Selector Used by objective-C.

Sel shootselector = @ selector (shoot );

Sel shootatselector = @ selector (shootat :);

Sel movetoselector = @ selector (moveTo: withpencolor :);

 

In the nsobject class, you can use the performselector method or the performselector: withobject: Method to execute the selector. For example:

[OBJ into mselector: shootselector];

[OBJ ready mselector: shootatselector withobject: coordinate];

 

In the nsarray class, you can use makeobjectsperformselector: to perform the selector operation. For example:

[Array makeobjectsperformselector: shootselector]; // cool, huh?

[Array makeobjectsperformselector: shootatselector withobject: Target]; // target is an ID

 

In the uibutton class, you can use the-(void) addtarget :( ID) anobject action :( SEL) action...; Method to execute the selector. For example:

[Button addtarget: Self action: @ selector (digitpressed :)...];

Content from:

Http://mikixiyou.iteye.com/blog/1587051

Advanced:

Runtime of objective-C

Http://blog.sina.com.cn/s/blog_4cd8dd130101juf1.html

Http://www.linuxidc.com/Linux/2012-02/54989.htm

Http://www.cocoachina.com/macdev/objc/2013/0115/5541.html