Object-c KVC KVO (with attributes array, book object, array loaded book object)

KVC (keyvaluecoding) "Key-value-code" is a mechanism for accessing class instance variables directly through the string's name (key).
KVC can be used to access and set the value of an instance variable.
Setting mode: [Self setvalue:aname forkey:@ "name"]

[Self setvalue:aname forkeypath:@ "Person.name"]

Access mode: astring = [self valueforkey:@ "name"]
astring = [Self valueforkeypath:@ "person.name"]

1 Main function Contents2Person *xiaoli =[[Person alloc]init];3         //Book *book = [[book Alloc]init];4         //[book Addmyobserver];5         6[Xiaoli Setbookname:@"the dream of Red mansions"Andprice: -];7[Xiaoli Setbookname:@""Kingdoms""Andprice:56.5];8[Xiaoli Setbookname:@""Outlaws of the Marsh""Andprice:68.8];9[Xiaoli Setbookname:@""Journey to the Monkey""Andprice:75.2];Ten          OneNsarray *array = [Xiaoli valueforkeypath:@"Bookarray"]; A          -          for(Book *bookinchArray) -         { the              -NSLog (@"%@ %@", [book Valueforkey:@"BookName"],[book Valueforkey:@" Price"]); -         } -  +  -  + #import<Foundation/Foundation.h> A #import "Book.h" at  - @interfacePerson:nsobject - { -NSString *name; -Nsmutablearray *Bookarray; -Book *Abook; in } -  to- (void) Setbookname: (NSString *) BookName Andprice: (float) Price; +  - @end the  *  $ Panax Notoginseng  - #import "Person.h" the #import "Book.h" +  A @implementation Person the  +- (void) Setbookname: (NSString *) BookName Andprice: (float) Price - { $     //if Bookarrar is not initialized, initialize the $     if(!Bookarray) { -Bookarray =[[Nsmutablearray alloc]init]; -     } the      -Book *book =[[book Alloc]init];Wuyi      the     //start listening to changes in the title - [book Addmyobserver]; Wu      -[Self Setvalue:book forkey:@"Abook"]; About[Self setvalue:bookname Forkeypath:@"Abook.bookname"]; $      -     //the price is encapsulated into NSNumber data assigned to BookName, which is automatically converted to float when the bookname is read. -NSNumber *price1 =[NSNumber Numberwithfloat:price]; -[Self Setvalue:price1 Forkeypath:@"Abook.price"]; A      +     //to load a book into an array the [Bookarray Addobject:abook]; -  $ } the  the @end the  the  -  in  the #import<Foundation/Foundation.h> the  About @interfaceBook:nsobject the  the { theNSString *BookName; +     floatPrice ; - } the Bayi- (void) Addmyobserver; the  the @end -  -  the  the  the #import "Book.h" the  - @implementation Book the  the- (void) Addmyobserver the {94     //Registering Listener Objects the[Self addobserver:self Forkeypath:@"BookName"options:nskeyvalueobservingoptionnew Context:nil]; the     //Observer the }98  About     //Listener Property Instance value changes -- (void) Observevalueforkeypath: (NSString *) KeyPath Ofobject: (ID)ObjectChange: (nsdictionary *) Change context: (void*) Context101 {102NSLog (@"bookname%@", change);103 }104  the- (void) Dealloc106 {107     //Remove Listener108[Self removeobserver:self Forkeypath:@"BookName"];109 [Super Dealloc]; the }111  the 113 @end

Object-c KVC KVO (with attributes array, book object, array loaded book object)