Make sense of Notification Watcher source objective-c
- by Chris
From Notification Watcher source.
- (void)selectNotification:(NSNotification*)aNotification {
id sender = [aNotification object];
[selectedDistNotification release];
selectedDistNotification = nil;
[selectedWSNotification release];
selectedWSNotification = nil;
NSNotification **targetVar;
NSArray **targetList;
if (sender == distNotificationList) {
targetVar = &selectedDistNotification;
targetList = &distNotifications;
} else {
targetVar = &selectedWSNotification;
targetList = &wsNotifications;
}
if ([sender selectedRow] != -1) {
[*targetVar autorelease];
*targetVar = [[*targetList objectAtIndex:[sender selectedRow]] retain];
}
if (*targetVar == nil) {
[objectText setStringValue:@""];
} else {
id obj = [*targetVar object];
NSMutableAttributedString *objStr = nil;
if (obj == nil) {
NSFont *aFont = [objectText font];
NSDictionary *attrDict = italicAttributesForFont(aFont);
objStr = [[NSMutableAttributedString alloc] initWithString:@"(null)"
attributes:attrDict];
} else {
/* Line 1 */ objStr = [[NSMutableAttributedString alloc] initWithString:
[NSString stringWithFormat:@" (%@)", [obj className]]];
[objStr addAttributes:italicAttributesForFont([objectText font])
range:NSMakeRange(1,[[obj className] length]+2)];
if ([obj isKindOfClass:[NSString class]]) {
[objStr replaceCharactersInRange:NSMakeRange(0,0) withString:obj];
} else if ([obj respondsToSelector:@selector(stringValue)]) {
[objStr replaceCharactersInRange:NSMakeRange(0,0)
withString:[obj performSelector:@selector(stringValue)]];
} else {
// Remove the space since we have no value to display
[objStr replaceCharactersInRange:NSMakeRange(0,1) withString:@""];
}
}
[objectText setObjectValue:objStr];
/* LINE 2 */ [objStr release];
}
[userInfoList reloadData];
}
Over at //LINE 2 objStr is being released. Is this because we are assigning it with alloc in //LINE 1?
Also, why is //LINE 1 not:
objStr = [NSMutableAttributedString* initWithString:@"(null)"
attributes:attrDict]
If I create a new string like
(NSString*) str = [NSString initWithString:@"test"];
...
str = @"another string";
Would I have to release str, or is this wrong and if I do that I have to use [[NSString alloc] initWithString:@"test"]?
Why isn't the pointer symbol used as in [[NSString* alloc] ...?
Thanks
