Value and assignment of KVC

. m file

1 #import<Foundation/Foundation.h>2 #import "Person.h"3 intMainintargcConst Char*argv[]) {4 @autoreleasepool {5         /*6 KVC: Full name Key value Coding is an indirect way to access an object instance variable to assign a value to the corresponding instance variable in the object7 with Setvalue:forkey:8 Assignment principle: Given a key, such as name9 1. First find the object has no corresponding SetName method, if there is a direct call to the method to assign value, if there is no go to step 2Ten 2. If there is no defined instance variable for _ then, if you have to assign a value directly to the instance variable, go to step 3 One 3. The Lookup object has no definition instance variable called name, if you have to assign a value directly to the instance variable, otherwise go to step 4 A 4. Method Setvalue:forundefinedkey in the auto-call object: - KVC Value procedure: Call Valueforkey: Given a key such as name - 1. The Lookup object has no corresponding getter method, if any, call the method to return the value of the corresponding instance variable, if there is no go to step 2 the 2. Then find out if you have defined the corresponding _name instance variable, if you have the value stored directly out of the instance variable, otherwise go to step 3 - 3. Then find out if the corresponding name instance variable is defined, and if there is a value stored directly out of the instance variable, go to step 4 - 4. Method Value:forundefindkey in the auto-call object: -           +          */ -         //KVC Assignment Process +Person *person =[[Person alloc] init]; A[Person SetValue:@"pilaf King"Forkey:@"name"]; at[Person SetValue:@"Monkey King"Forkey:@"name"]; -          -NSLog (@"%@", person.name); -         //KVC The process of taking value -NSLog (@"%@", [Person Valueforkey:@"name"]); -         //Setvalue:forkeypath: Assigning or taking values to instance variables based on path in[Person SetValue:@"Lele"Forkeypath:@"Person.name"]; -NSLog (@"%@", [Person Valueforkeypath:@"Person.name"]); to         //use KVC to encapsulate dictionaries into objects +Nsdictionary *dict = @{@"name":@"Xiao Ming",@"Sex":@"male",@"Address":@"you guessed"}; -         //person.name = [dict objectforkey:@ "name"]; the         //person.sex = [dict objectforkey:@ "Sex"]; *         //person.address = [dict objectforkey:@ "Address"]; $ Panax Notoginseng [Person setvaluesforkeyswithdictionary:dict]; -NSLog (@"%@", person); the          +     } A     return 0; the}

Use KVC to encapsulate dictionaries into objects that are used to assign values to objects directly.

Person.h file

1 #import <Foundation/Foundation.h>23@interface  person:nsobject 4 @property (nonatomic, retain) NSString *name; 5 @property (nonatomic, retain) nsstring *sex; 6 @property (nonatomic, retain) NSString *address; 7 @end

PERSON.M file

1 @implementation Person2-(ID) Valueforundefinedkey: (NSString *) Key3 {4NSLog (@"Lingling said she hit the code and found her wife.");5     returnNil;6 }7 //if there is no corresponding key, then the system automatically calls the following method, the method defaults to throw an exception, so that the system crashes.8 //If you don't want the method to throw an exception, then we need to rewrite this method ourselves.9-(void) SetValue: (ID) value Forundefinedkey: (nonnull NSString *) KeyTen { OneNSLog (@"not stupid, not yet."); A      - } - //override this method to output data from the original object (not Unicode character encoding) the-(NSString *) Description - { -     return[NSString stringWithFormat:@"name =%@,sex =%@, address =%@", self.name,self.sex,self.address]; - } + @end

Value and assignment of KVC