Responding to NSManagedObject lifecycle events with automatic callback to simple method naming convention.

gistfile1.m

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//
//  NSManagedObject+AutoUpdating.h
//  Piggie
//
//  Created by Meiwin Fu on 14/5/12.
//  Copyright (c) 2012 –MwF. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface NSManagedObject (AutoUpdating)
- (void)updateForKey:(NSString *)key;
- (void)updateForAllKeys;
@end

@interface NSAutoUpdatingManagedObject : NSManagedObject
@end


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//
//  NSManagedObject+AutoUpdater.m
//  Piggie
//
//  Created by Meiwin Fu on 14/5/12.
//  Copyright (c) 2012 –MwF. All rights reserved.
//

#import "NSManagedObject+AutoUpdating.h"

@implementation NSManagedObject (AutoUpdating)
- (void)updateForKey:(NSString *)key;
{
  NSString * methodName = nil;
  key = [key stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
  if (key && [key length]) {
    methodName = [NSString stringWithFormat:@"updateFor%@%@Change", 
                  [[key substringToIndex:1] uppercaseString],
                  ([key length] > 1 ? [key substringFromIndex:1] : @"")];
  }
  if (methodName) {
    SEL methodSEL = sel_getUid([methodName UTF8String]);
    BOOL methodImplemented = [self respondsToSelector:methodSEL];
    if (methodImplemented) {
      [self performSelector:methodSEL];
    }
  }
}

- (void)updateForAllKeys;
{
  NSEntityDescription * entity = self.entity;
  NSArray * props = entity.properties;
  for (NSPropertyDescription * prop in props) {
    [self updateForKey:prop.name];
  }
}
@end

@implementation NSAutoUpdatingManagedObject

- (void)awakeFromFetch;
{
  [super awakeFromFetch];
  [self updateForAllKeys]; 
}
- (void)awakeFromInsert;
{
  [super awakeFromInsert];
  [self updateForAllKeys]; 
}
- (void)didChangeValueForKey:(NSString *)key;
{
  [super didChangeValueForKey:key];
  [self updateForKey:key];
}
- (void)didTurnIntoFault;
{
  [super didTurnIntoFault];
  [self updateForAllKeys];
}

@end