Dear Coco-dev People,
I've modified Mike Ferris's Sketch example so that the SKTGraphic class has an
extra ivar, an NSMutableString. When I save and open a Sketch document I can see
in the debugger that my instance variable has become "invalid" but I can't figure
out what I'm doing wrong.
I've tried a number of code "permutations" but nothing has worked: I tried two
approaches to build the dictionary item for my new ivar, but neither one worked.
You can look at the code I've commented out to see what I tried. I also created a
setTheCellID accessor (just for use during object creation) which only updated the
new ivar to see if the other parts of the setCellID accessor (undo and
notification) were causing the problem. It didn't seem to matter which accessor I
used.
I've looked in Hillegass 2nd ed. and read Scott Stevenson's app. note "Saving
Application Data" but the Sketch filing paradigm differs from their approaches.
I've also reviewed Michael Beam's two Strings articles on oreillynet, Apple's
online Strings documentation, the Coco-dev archive, and Googled for clues. I'm
stuck on this.
Comments, suggestions and code will be greatly appreciated!
Joel Norvell
Here are pertinent snippets of the Modified Sketch code.
"..." indicates Sketch code shortened for brevity..
"*** ADDED" indicates code I've added for the _cellID ivar.
// from SKTGraphic.h
@interface SKTGraphic : NSObject <NSCopying> {
@private
...
NSMutableString *_cellID; // *** ADDED
}
// from SKTGraphic.m
- (id)init {
self = [super init];
if (self) {
...
[self setTheCellID:[[NSMutableString alloc] initWithString:@"A01"]]; // ***
ADDED
}
return self;
}
- (void)dealloc {
[_fillColor release];
[_strokeColor release];
[_cellID release]; // *** ADDED
[super dealloc];
}
- (id)copyWithZone:(NSZone *)zone {
id newObj = [[[self class] allocWithZone:zone] init];
// Document is not "copied". The new graphic will need to be inserted into a
document.
...
[newObj setTheCellID:[self cellID]]; // *** ADDED
return newObj;
}
- (void)setCellID:(NSMutableString *)theCellID { // *** ADDED Accessor method
if (_cellID != theCellID) {
[[[self undoManager] prepareWithInvocationTarget:self]
setCellID:theCellID];
_cellID = theCellID;
[self didChange];
}
}
- (void)setTheCellID:(NSMutableString *)theCellID { // *** ADDED Accessor method
if (_cellID != theCellID) {
_cellID = theCellID;
}
}
- (NSMutableString *)cellID { // *** ADDED Accessor method
return _cellID;
}
// for Persistence
NSString *SKTCellIDKey = @"CellID"; // *** ADDED
- (NSMutableDictionary *)propertyListRepresentation {
NSMutableDictionary *dict = [NSMutableDictionary dictionary];
NSString *className = NSStringFromClass([self class]);
...
// [dict setObject:cellID forKey:SKTCellIDKey]; // *** ADDED
[dict setObject:[NSArchiver archivedDataWithRootObject:[self cellID]]
forKey:SKTCellIDKey]; // *** ADDED
return dict;
}
- (void)loadPropertyListRepresentation:(NSDictionary *)dict {
id obj;
...
// obj = [dict objectForKey:SKTCellIDKey]; // *** ADDED
// if (obj) { // *** ADDED
// [self setTheCellID:obj]; // *** ADDED
// } // *** ADDED
obj = [dict objectForKey:SKTCellIDKey]; // ***
ADDED
if (obj) { // ***
ADDED
[self setTheCellID:[NSUnarchiver unarchiveObjectWithData:obj]]; // ***
ADDED
} // ***
ADDED
return;
}
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