Runtime Summary Black Magic

(a) The method of setting up the picture of the interception Exchange system

#import <UIKit/UIKit.h>@interface  UIImage (myimage)+ (UIImage *) Thenewimagename: ( NSString *) name; @end

#import "uiimage+myimage.h"#import<objc/runtime.h>@implementationUIImage (myimage)+ (void) load{Staticdispatch_once_t Oncetoken; Dispatch_once (&oncetoken, ^{        //how to swap settings for a picture#pragmaMark---If you need to exchange the method is "-" instance method with Class_getinstancemethod, if the "+" class method is used Class_getclassmethodMethod Originmethod=Class_getclassmethod (Self, @selector (imagenamed:)); Method Custommethod=Class_getclassmethod (Self, @selector (thenewimagename:));    Method_exchangeimplementations (Originmethod, Custommethod); });}+ (UIImage *) Thenewimagename: (NSString *) name{NSString*thename = [NSString stringWithFormat:@"new_%@", name]; return[UIImage thenewimagename:thename];}@end

(ii) Adding attributes to System classes

#import <Foundation/Foundation.h>@interface  nsdictionary (mydictionary)//  Add attribute @property to dictionary class (nonatomic, copy) NSString **gender; @end

#import "Nsdictionary+mydictionary.h"#import<objc/runtime.h>@implementationnsdictionary (mydictionary)/** In the extension there are * objects: object to be associated key: The key value of the property to be associated with Polocy: is the enum type enum {objc_association_assign = 0, the Property object being decorated is a weakly referenced Objc_association_retain_nonatomic = 1, strong reference, non-thread-safe objc_association_copy_nonatomic = 3, specifying the associated replication object, non-thread-safe objc_association _retain = 01401, specifying a strong reference to the associated object, thread-safe default Atomic objc_association_copy = 01403 Specifies the related replication object, which is atomic} by default; */- (void) SetName: (NSString *) name{objc_setassociatedobject (self, @selector (name), name, objc_association_copy_nonatomic);}-(NSString *) name{returnObjc_getassociatedobject (self, @selector (name));}- (void) Setgender: (NSString *) gender{objc_setassociatedobject (self, @selector (gender), gender, objc_association_copy_nonatomic);}-(NSString *) gender{returnObjc_getassociatedobject (self, @selector (gender));}@end

(iii) Use runtime to archive class attributes

#import <Foundation/Foundation.h>@interface  person:nsobject-(void) Eat; -(void**gender; @property (nonatomic, assign) Nsinteger age; @end

//Archive- (void) Encodewithcoder: (Nscoder *) acoder{unsignedintCount =0; //1. Get an array of variable listsIvar *ivarlist = Class_copyivarlist ([selfclass], &count); //2. Cycle     for(inti =0; I < count; i++) {        //3. Get the variable nameIvar Ivar =Ivarlist[i]; //4. Converting a C-language string to an OC stringNSString *ivarstring =[NSString Stringwithutf8string:ivar_getname (Ivar)]; //5. Archive[Acoder encodeobject:[self valueforkey:ivarstring] forkey:ivarstring]; }}//Anti-archiving-(Instancetype) Initwithcoder: (Nscoder *) adecoder{ Self=[Super Init]; if(self) {unsignedintCount =0; Ivar*ivarlist = Class_copyivarlist ([selfclass], &count);  for(inti =0; I < count; i++) {Ivar Ivar=Ivarlist[i]; NSString*ivarstring =[NSString Stringwithutf8string:ivar_getname (Ivar)]; //Anti-archiving[self Setvalue:[adecoder decodeobjectforkey:ivarstring] forkey:ivarstring]; }    }    returnSelf ;}

Runtime Summary Black Magic