Ios--runtime/swizzle

What is runtime?

Runtimec also known as the runtime. is the system at the time of the operation of some mechanism.

is a set of underlying C language API(contains a lot of powerful practical C language data types,C language functions)

The OC code that we write usually turns into the runtime code at the bottom.

Such as:
Xqpersion *persion = [Xqpersion alloc] init];

[Persion Run];

At compile time, runtime will convert the above code into:

Objc_msgsend (Persion, @selector (run));

What's the use of Runtim?

Can dynamically generate, modify, delete a class, a member variable, a method.

can be get all the member variables inside a class, Method

Ivar * Class_copyivarlist: get all member variables inside a class

Method * Class_copymethodlist: Get all the methods inside a class

Method Class_getinstancemethod: Get an instance approach (object method, minus - start)

Method Class_getclassmethod: Get a class approach (plus + start)

Method_exchangeimplementations: A specific implementation of 2 methods of Exchange

What is Swizzle?

Calling a method in Objective-c is actually sending a message to an object, and the only way to find the message is by selector's name.

By using the dynamic characteristics of objective-c, the corresponding method of selector can be realized at runtime to achieve the purpose of linking to the method.

Each class has a list of methods that hold the mapping of selector's name and method implementation. IMP is a bit like a function pointer, pointing to a concrete method implementation.

Swizzle is the implementation of exchanging two methods while the program is running.

Ios--runtime/swizzle