KVC、NSDictionary、KVO 物件狀態變更通知

KVC = Key Value Coding

 
@interface Member : NSObjext{
  NSString *name;
  NSString *addr;
  NSString *tel;
  NSInteger *wallet;
}

read方法

 
NSString *name = [member valueForKey:@"name"];

若Application有物件

 
NSString *name = [application valueForKeyPath:@"member.name"];

set方法

 
[member setValue:@"bob" forKey:@"name"];

 
[application setValue:@"bob" forKey:@"member.name"];

NSDictionary

read

 
@interface Member : NSObjext{
  NSString *name;
  NSString *addr;
  NSString *tel;
  NSInteger wallet;
}
@property (nonatomic,retain) NSString *name;
@property (nonatomic,retain) NSString *addr;
@property (nonatomic,retain) NSString *tel;
@property (nonatomic,retain) NSString wallet;

@implementation Member
@synthesize name,addr,tel,wallet;
@end

NSDictionary *
read

 
NSDictionary *properties = [self dictionaryWithValuesForKeys:[NSArray arrayWithObjects:@"name",@"addr",@"tel",@"wallet",nil];

未知的key值 valueForUndefinedKey:
硬找會發生NSUndefinedKeyException

NSDictionary中
NSInteger會被轉成->NSNumber
nil會被轉成->NSNull

set方法

 
NSDictionary *properties = [NSDictionary dictionaryWithObjectsAndKeys:@"bob",@"name",@"addr",@"綠島",@"0912345678", [NSNumber numberWithInt:30000],@"wallet",nil];
[self setValuesForKeyWithDictionary:properties];

動態取得屬性名稱

在NSObject加入方法

 
#import 
@interface NSObject(Private)
+(NSArray *)propertyName;
@end

@implementation NSObject (Private)
+(NSArray *)propertyNames{
  unsigned int cnt,i;
  objc_property_t *properties = class_copyPropertyList([self class],&cnt);
  NSMutalbeArray *propNames = [NSMutableArray arrayWithCapacity:cnt];
  for(i = 0 ; i < cnt ; i++){
    objc_property_t property = properties[i];
    const char *propName = property_gerName(property);
    NSString *propertyName = [NSString stringWithUTF8String:propName];
    [propNames addObject:propertyName];
  }
  free(properties)
  return propNames;   
}
@end

NSDictionary *properties = [self dictionaryWithValuesForKeys:[User propertyNames]];

KVO = Key Value Observers