KVC example and fineui online example

KVC example and fineui online example

KVC-key value Coding allows us to assign values to attribute values in the form of key-value encoding.

Refer to the image on the official website of apple ..

1. KVC

Define a Person class

. H file

   1:  #import <Foundation/Foundation.h>

   2:  

   3:  @interface Person : NSObject

   4:  {

   5:     NSString *name;

   6:  }

   7:   

   8:  @end

. M file

   1:  #import "Person.h"

   2:   

   3:  @implementation Person

   4:   

   5:  @end

 

You cannot assign values to names by using common methods to obtain attributes. In this case, you can use KVC to set and set attributes.

   1:  - (void)viewDidLoad {

   2:      [super viewDidLoad];

   3:      // Do any additional setup after loading the view, typically from a nib.

   4:     Person  person=[[Person alloc]init];

   5:      [person setValue:@"keith" forKey:@"name"];

   6:      NSLog(@"name is %@",[person valueForKey:@"name"]);

   7:  }

Output: 21:51:12. 237 KVCtest [543: 10453] name is keith

SetValue: forKey:

ValueForKey:

2. Key Path

What should I do if the class contains other classes and access the attributes of this class. You can use setValue: forKeyPath: And valueForKeyPath to set and obtain

For example, define a car

. H file

#import <Foundation/Foundation.h>@interface Car : NSObject{    NSString *carname;}@end

Change. h of Person

#import <Foundation/Foundation.h>@class Car;@interface Person : NSObject{    NSString *name;    Car *hiscar;}-(id)init;@end

. M is

#import "Person.h"#import "Car.h"@implementation Person-(id)init{    if (self=[super init]) {        hiscar=[[Car alloc]init];    }    return self;}@end

The car instantiation is implemented here. If this is not done, hiscar cannot be assigned a value because it is not initialized during key-value programming.

Call:

-(Void) viewDidLoad {[super viewDidLoad]; // Do any additional setup after loading the view, typically from a nib. person * person = [[Person alloc] init]; [person setValue: @ "keith" forKey: @ "name"]; [person setValue: @ "QQ" forKeyPath: @ "hiscar. carname "]; NSLog (@" name is % @, hiscar is % @ ", [person valueForKey: @" name "], [person valueForKeyPath: @" hiscar. carname "]);/* or */Car * car = [[Car alloc] init]; [car setValue: @" BeiKy "forKey: @" carname "]; [person setValue: car forKey: @ "hiscar"]; NSLog (@ "name is % @, hiscar is % @", [person valueForKey: @ "name"], [person valueForKeyPath: @ "hiscar. carname "]);}

Output result

22:45:47. 392 KVCtest [1031: 25564] name is keith, hiscar is QQ
22:45:47. 394 KVCtest [1031: 25564] name is keith, hiscar is BeiKy

3. Type encapsulation and conversion

 

Modify the Person. h file again

# Import <Foundation/Foundation. h> @ class Car; @ interface Person: NSObject {NSString * name; Car * hiscar; NSInteger age; // Add an age type NSInteger}-(id) init; @ end

 

So how can this happen during setup?

-(Void) viewDidLoad {[super viewDidLoad]; // Do any additional setup after loading the view, typically from a nib. person * person = [[Person alloc] init]; [person setValue: @ "keith" forKey: @ "name"]; [person setValue: @ "QQ" forKeyPath: @ "hiscar. carname "]; [person setValue: @" 24 "forKeyPath: @" age "]; // assign an NSLog (@" name is % @, is % @ old, hiscar is % @ ", [person valueForKey: @" name "], [person valueForKey: @" age "], [person valueForKeyPath: @" hiscar. carname "]);}

The result is:

22:56:08. 873 KVCtest [1086: 27956] name is keith, is 24 old, hiscar is QQ

4. Operation set

 

Add an otherPerson to Person

#import <Foundation/Foundation.h>@class Car;@interface Person : NSObject{    NSString *name;    Car *hiscar;    NSInteger age;    NSMutableArray *otherPerson;}-(id)init;@end

Attribute. @ sum. attribute, and @ count, @ avg, @ max. @ min

-(void)kvcCollection{    Person *person=[[Person alloc]init];    [person setValue:@"keith" forKey:@"name"];    Person *person1=[[Person alloc]init];    Person *person2=[[Person alloc]init];    Person *person3=[[Person alloc]init];    Person *person4=[[Person alloc]init];    NSMutableArray *others=[[NSMutableArray alloc]initWithObjects:person1,person2,person3,person4, nil];    NSInteger agenum=20;    for (Person *p in others) {        [self setage:p age:[[NSString alloc]initWithFormat:@"%ld",agenum++]];    }    [person setValue:others forKey:@"otherPerson"];    NSLog(@"other's age is %@",[person valueForKeyPath:@"otherPerson.age"]);    NSLog(@"the avg age is %@",[person valueForKeyPath:@"otherPerson.@avg.age"]);    NSLog(@"the sum age is %@",[person valueForKeyPath:@"otherPerson.@sum.age"]);    NSLog(@"the count person is %@",[person valueForKeyPath:@"otherPerson.@count.age"]);    NSLog(@"the min age is %@",[person valueForKeyPath:@"otherPerson.@min.age"]);    NSLog(@"the max age is %@",[person valueForKeyPath:@"otherPerson.@max.age"]);    }-(void)setage:(Person *)person age:(NSString *)age{    [person setValue: age forKey:@"age"];}

 

Output

23:51:00. 180 KVCtest [1346: 42300] other's age is (
20,
21,
22,
23
)
23:51:00. 183 KVCtest [1346: 42300] the avg age is 21.5
23:51:00. 183 KVCtest [1346: 42300] the sum age is 86
23:51:00. 184 KVCtest [1346: 42300] the count person is 4
23:51:00. 184 KVCtest [1346: 42300] the min age is 20
23:51:00. 184 KVCtest [1346: 42300] the max age is 23

 

Thank you for your reference.

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