Property And Synthesize

gratuitousFloat has a dynamic directive—it is supported using direct method implementations;

nameAndAge does not have a dynamic directive, but this is the default value; it is supported using a direct method implementation (since it is read-only, it only requires a getter) with a specified name (nameAndAgeAsString).

@protocol Link
@property id next
@end

@interface MyClass : NSObject {
NSTimeInterval intervalSinceReferenceDate;
CGFloat gratuuitousFloat;
id nextLink;
}

@property (readonly) NSTimeInterval creationTimestamp;
@property (copy) NSString *name;
@property (readonly, getter=nameAndAgeAsString) NSString *nameAndAge;

@implementation MyClass

@synthesize creationTimestamp = intervalSinceReferenceDate, name;
// Synthesizing 'name' is an error in legacy runtimes;
// in modern runtimes, the instance variable is synthesized.

@synthesize next = nextLink;
// Uses instance variable "nextLink" for storage.

@dynamic gratuitousFloat;
// This directive is not strictly necessary.

- (CGFloat)gratuitousFloat {
return gratuitousFloat;
}
- (void)setGratuitousFloat:(CGFloat)aValue {
gratuitousFloat = aValue;
}

- (NSString *)nameAndAgeAsString {
return [NSString stringWithFormat:@"%@ (%fs)", [self name],
[NSDate timeIntervalSinceReferenceDate] - intervalSinceReferenceDate];
}

- (id)init {
if (self = [super init]) {
intervalSinceReferenceDate = [NSDate timeIntervalSinceReferenceDate];
}
return self;
}

- (void)dealloc {
[nextLink release];
[name release];
[super dealloc];
}

@end