iOS Black Magic Method swizzling

This black magic should belong to OC, it is based on runtime implementation of bogus DAFA.

So what is method swizzling? From the literal point of view is called the method of coordination, probably this means. Use this magic to replace an existing method with a custom method, a bogus, a rescue.

Using the method is simple, the code is basically the following framework. But it has a strong magic, this is a way to hook ah.

/** * Method swizzling * Black magic Bogus * * #import "uiviewcontroller+extension.h" #import <objc/runtime.h>@ Implementation Uiviewcontroller (Extension)//In order to ensure certain execution put the code into + (void) load; + (void) load {[Super load]; //thread safe    Perform only one static dispatch_once_t Oncetoken; Dispatch_once (&oncetoken, ^{//Get class class = [Self class];//class class = Object_getcla        SS ((ID) self);        Package selector SEL originalselector = @selector (viewwillappear:);        SEL swizzledselector = @selector (lw_viewwillappear:);        Encapsulation Method Originalmethod = Class_getinstancemethod (class, Originalselector);        Method Swizzledmethod = Class_getinstancemethod (class, Swizzledselector); Add method BOOL Methoddidadd = Class_addmethod (class, Originalselector, Method_getimplementation (Swizzledmethod), meth        Od_gettypeencoding (Swizzledmethod)); if (Methoddidadd) {//Replace method Class_replacemethod (class, Originalselector, MethoD_getimplementation (Swizzledmethod), method_gettypeencoding (Swizzledmethod));        }else {//Exchange method Method_exchangeimplementations (Originalmethod, Swizzledmethod); }    });}    #pragma mark-Custom Magic Method-(void) Lw_viewwillappear: (BOOL) animated {[Self lw_viewwillappear:animated]; NSLog (@ "BLack Magic");}

Attention:

1 + (void) load;

2 dispatch_once;

3 [self lw_viewwillappear:animated]; Do not return to the dead loop if [self viewwillappear:animated];

iOS Black Magic Method swizzling