tasks a-s

Task/Object-serialization/Objective-C/object-serialization.m

@@ -0,0 +1,185 @@
+#import <Foundation/Foundation.h>
+
+// a fantasy two level hierarchy
+@interface Animal : NSObject <NSCoding>
+{
+  NSString *animalName;
+  int numberOfLegs;
+}
+- (id) initWithName: (NSString*)name andLegs: (NSInteger)legs;
+- (void) dump;
+// the following allows "(de)archiving" of the object
+- (void) encodeWithCoder: (NSCoder*)coder;
+- (id) initWithCoder: (NSCoder*)coder;
+@end
+
+@implementation Animal
+- (id) initWithName: (NSString*)name andLegs: (NSInteger)legs
+{
+  if ((self = [super init])) {
+    animalName = [name retain];
+    numberOfLegs = legs;
+  }
+  return self;
+}
+- (void) dealloc
+{
+  [animalName release];
+  [super dealloc];
+}
+- (void) dump
+{
+  NSLog(@"%@ has %d legs", animalName, numberOfLegs);
+}
+// ========
+- (void) encodeWithCoder: (NSCoder*)coder
+{
+  [coder encodeObject: animalName forKey: @"Animal.name"];
+  [coder encodeInt: numberOfLegs forKey: @"Animal.legs"];
+}
+- (id) initWithCoder: (NSCoder*)coder
+{
+  if ((self = [super init])) {
+    animalName = [[coder decodeObjectForKey: @"Animal.name"] retain];
+    numberOfLegs = [coder decodeIntForKey: @"Animal.legs"];
+  }
+  return self;
+}
+@end
+
+@interface Mammal : Animal <NSCoding>
+{
+  BOOL hasFur;
+  NSMutableArray *eatenList;
+}
+- (id) initWithName: (NSString*)name hasFur: (BOOL)fur;
+- (void) addEatenThing: (NSString*)thing;
+- (void) dump;
+// for archiving / dearchiving:
+- (void) encodeWithCoder: (NSCoder*)coder;
+- (id) initWithCoder: (NSCoder*)coder;
+@end
+
+@implementation Mammal
+- (id) init
+{
+  if ((self = [super init])) {
+    hasFur = NO;
+    eatenList = [[NSMutableArray alloc] initWithCapacity: 10];
+  }
+  return self;
+}
+- (id) initWithName: (NSString*)name hasFur: (BOOL)fur
+{
+  if ((self = [super initWithName: name andLegs: 4])) {
+    hasFur = fur;
+    eatenList = [[NSMutableArray alloc] initWithCapacity: 10];
+  }
+  return self;
+}
+- (void) addEatenThing: (NSString*)thing
+{
+  [eatenList addObject: thing];
+}
+- (void) dealloc
+{
+  [eatenList release];
+  [super dealloc];
+}
+- (void) dump
+{
+  [super dump];
+  NSLog(@"has fur? %@", (hasFur) ? @"yes" : @"no" );
+  // fast enum not implemented yet in gcc 4.3, at least
+  // without a patch that it seems to exist...
+  NSEnumerator *en = [eatenList objectEnumerator];
+  id element;
+  NSLog(@"it has eaten %d things:", [eatenList count]);
+  while( (element = [en nextObject]) != nil )
+    NSLog(@"it has eaten a %@", element);
+  NSLog(@"end of eaten things list");
+}
+// ========= de/archiving
+- (void) encodeWithCoder: (NSCoder*)coder
+{
+  [super encodeWithCoder: coder];
+  [coder encodeBool: numberOfLegs forKey: @"Mammal.hasFur"];
+  [coder encodeObject: eatenList forKey: @"Mammal.eaten"];
+}
+- (id) initWithCoder: (NSCoder*)coder
+{
+  if ((self = [super initWithCoder: coder])) {
+    hasFur = [coder decodeBoolForKey: @"Mammal.hasFur"];
+    eatenList = [[coder decodeObjectForKey: @"Mammal.eaten"] retain];
+  }
+  return self;
+}
+@end
+
+
+int main()
+{
+  Mammal *aMammal;
+  Animal *anAnimal;
+  NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
+
+  // let us create a fantasy animal
+  anAnimal = [[Animal alloc]
+	       initWithName: @"Eptohippos"
+	       andLegs: 7
+	      ];
+  // for some reason an Eptohippos is not an horse with 7 legs,
+  // and it is not a mammal, of course...
+
+  // let us create a fantasy mammal (which is an animal too)
+  aMammal = [[Mammal alloc]
+	      initWithName: @"Mammaluc"
+	      hasFur: YES
+	     ];
+  // let us add some eaten stuff...
+  [aMammal addEatenThing: @"lamb"];
+  [aMammal addEatenThing: @"table"];
+  [aMammal addEatenThing: @"web page"];
+
+  // dump anAnimal
+  NSLog(@"----- original Animal -----");
+  [anAnimal dump];
+
+  // dump aMammal...
+  NSLog(@"----- original Mammal -----");
+  [aMammal dump];
+
+  // now let us store the objects...
+  NSMutableData *data = [[NSMutableData alloc] init];
+  NSKeyedArchiver *arch = [[NSKeyedArchiver alloc]
+			    initForWritingWithMutableData: data];
+  [arch encodeObject: anAnimal forKey: @"Eptohippos"];
+  [arch encodeObject: aMammal forKey: @"Mammaluc"];
+  [anAnimal release];
+  [aMammal release];
+  [arch finishEncoding];
+  [arch release];
+  [data writeToFile: @"objects.dat" atomically: YES];
+  [data release];
+
+  // now we want to retrieve the saved objects...
+  NSData *ldata = [[NSData alloc]
+		     initWithContentsOfFile: @"objects.dat"];
+  NSKeyedUnarchived *darch = [[NSKeyedUnarchiver alloc]
+	                       initForReadingWithData: ldata];
+  Animal *archivedAnimal = [darch decodeObjectForKey: @"Eptohippos"];
+  Mammal *archivedMammal = [darch decodeObjectForKey: @"Mammaluc"];
+  [darch finishDecoding];
+  [ldata release];
+  [darch release];
+
+  // now let's dump/print the objects...
+  NSLog(@"\n");
+  NSLog(@"----- the archived Animal -----");
+  [archivedAnimal dump];
+  NSLog(@"----- the archived Mammal -----");
+  [archivedMammal dump];
+
+  [pool release];
+  return EXIT_SUCCESS;
+}