KVC樣本，fineui線上樣本

KVC樣本，fineui線上樣本

KVC –key value Coding，可以讓我們通過索引值編碼的形式進行屬性值的賦值

參考蘋果官網的圖。。

1.KVC

定義一個Person類

.h檔案

   1:  #import <Foundation/Foundation.h>

   2:  

   3:  @interface Person : NSObject

   4:  {

   5:     NSString *name;

   6:  }

   7:   

   8:  @end

.m檔案

   1:  #import "Person.h"

   2:   

   3:  @implementation Person

   4:   

   5:  @end

 

通過普通的擷取屬性的方法是無法對name進行賦值和取值操作的，這種情況可以通過KVC來進行設定和取值

   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:  }

輸出： 2014-11-26 21:51:12.237 KVCtest[543:10453] name is keith

賦值用setValue:forKey:

取值用 valueForKey:

2.鍵路徑

如果類中包含其他的類怎麼辦呢，訪問這個類的屬性怎麼辦呢。可以使用setValue: forKeyPath: 和valueForKeyPath設定和擷取

如定義一個car

.h檔案

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

將Person的.h改成

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

.m為

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

這裡實現了car的執行個體化，如果不這麼做在索引值編程時候hiscar因為沒有初始化而出現無法賦值的情況

調用:

- (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"]);        /*或者這樣*/     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"]);}

輸出結果

2014-11-26 22:45:47.392 KVCtest[1031:25564] name is keith,hiscar is QQ
2014-11-26 22:45:47.394 KVCtest[1031:25564] name is keith,hiscar is BeiKy

3.類型封裝和轉換

 

再次修改Person.h檔案

#import <Foundation/Foundation.h>@class Car;@interface Person : NSObject{    NSString *name;    Car *hiscar;    NSInteger age;//增加一個年齡類型是NSInteger}-(id)init;@end

 

那麼如何在設定的時候會發生什麼呢？

- (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"];//為年齡賦值    NSLog(@"name is %@, is %@ old ,hiscar is %@",[person valueForKey:@"name"],[person valueForKey:@"age"],[person valueForKeyPath:@"hiscar.carname"]);}

結果是:

2014-11-26 22:56:08.873 KVCtest[1086:27956] name is keith, is 24 old ,hiscar is QQ

4.操作集合

 

在Person中添加一個otherPerson

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

屬性.@sum.屬性，還有@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"];}

 

輸出

2014-11-26 23:51:00.180 KVCtest[1346:42300] other's age is (
    20,
    21,
    22,
    23
)
2014-11-26 23:51:00.183 KVCtest[1346:42300] the avg age is 21.5
2014-11-26 23:51:00.183 KVCtest[1346:42300] the sum age is 86
2014-11-26 23:51:00.184 KVCtest[1346:42300] the count person is 4
2014-11-26 23:51:00.184 KVCtest[1346:42300] the min age is 20
2014-11-26 23:51:00.184 KVCtest[1346:42300] the max age is 23

 

本文參考 容芳志部落格，感謝這位博友

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