NSDate assign problem

Question

I would like to assign a date from one view controller to another

-(void) setCurrentDate:(NSDate newDate){
    self.currentDate = newDate;
    [self updateView];
}

While debugging I see the currentDate value out of scope and the application crashes with EXC_BAD_ACCESS.

Any help will be appreciated.

Answer 1

You need to pass the pointer to date. Something like this:

-(void) setCurrentDate:(NSDate* newDate){
    [self.currentDate release];
    self.currentDate = newDate;
    [self.currentDate retain];
    [self updateView];
}

Of course, your currentDate class variable should also be a NSDate pointer. It will be even better if you use a property instead of a custom made setter.

Answer 2

Possibly, you need to retain newDate or copy it, if it's possible.

What I mean:

1. You create newDate
2. You call setCurrentDate
3. You release newDate
4. [self updateView] try to use it and fails because it is already released.

You also can try NSZombieEnabled to catch this kind of bugs.

Answer 3

In your method name, you use (NSDate date). You forgot to include the "*", which makes it a pointer. The correct code should be

-(void) setCurrentDate:(NSDate *newDate){ // Notice the star after NSDate

    self.currentDate = newDate;
    [self updateView];

}

Answer 4

Besides that your setter should take NSDate by pointer (all class-type instances are passed by pointer in Objective-C), you are recursively calling the setter:
self.currentDate = foo results in [self setCurrentDate:foo] being called.

Correctly it should look e.g. like this (assuming a nonatomic, retain property):

- (void)setCurrentDate:(NSDate *)newDate {
    if (currentDate != newDate) {
        [currentDate release];
        [newDate retain];
        currentDate = newDate;
        [self updateView];
    }
}

Alternatively name that method different from the setter so you can use the synthesized setter:

- (void)updateDate:(NSDate *)newDate {
    self.currentDate = newDate;
    [self updateView];
}