iOS NSDate hates itself? UIDatePicker Question

[Buschmaster]

So here's my situation.

I have one UIDatePicker but it sets two different things. These two things are controlled by a Segmented controller. If it's on one side you're setting one date and if it's on the other side you're setting a different date. What I want it to do is save the date when you change the segmented controller. So first I have to save those dates. So when the datepicker is changed here is what is called:

-(void) pickerChangedDate:(id)sender {
	if([segmentedControl selectedSegmentIndex] == 0) {
		NSDate *aDate = [[NSDate alloc] init];
		aDate = [datePicker date];
		dateOne = aDate;
		[aDate release];
	} else {
		NSDate *aDate = [[NSDate alloc] init];
		aDate = [datePicker date];
		dateTwo = aDate;
		[aDate release];
	}			   
}

So what I'm doing here is seeing which side needs to be set. When that side is determined I go ahead and try and save it as dateOne or dateTwo which are NSDate properties. This caused no errors but this did. This is what's called when the segmented controller changes:

-(void) segmentedChanged:(id)sender {
	if([segmentedControl selectedSegmentIndex] == 0) {
		[datePicker setDate:dateOne animated:YES];
	} else {
		[datePicker setDate:dateTwo animated:YES];
	}	
}

Any ideas as to why this would cause a crash?

 

[robbieduncan]

You code makes no sense.

I have annotated it with comments:

-(void) pickerChangedDate:(id)sender {
	if([segmentedControl selectedSegmentIndex] == 0) {
		NSDate *aDate = [[NSDate alloc] init];
                // This is an error: why are you creating an object (alloc/init pair)
                // when you then set the variable to another date in the next
                // line.  This will leak memory.
		aDate = [datePicker date];
		dateOne = aDate;
                // Where to you retain aDate?
                // You've date dateOne to point at it, but as it's autoreleased it
                // will get dealloced real soon.  If you use dateOne after that
                // you will crash.
                // Also if dateOne is a property you are doing it all wrong: you
                // need to either use the date syntax or the setter directly
                // otherwise any existing object pointed to by dateOne will not
                // get released and you will leak more memory
		[aDate release];
                // Why are you releasing this date?
                // The date from datePicker will be autoreleased.  You should not release it.
	} else {
		NSDate *aDate = [[NSDate alloc] init];
		aDate = [datePicker date];
		dateTwo = aDate;
		[aDate release];
	}			   
}

Corrected code (assumes dateOne and dateTwo are properties with synthesized accessor/setter methods)

-(void) pickerChangedDate:(id)sender {
	if([segmentedControl selectedSegmentIndex] == 0) {
		self.dateOne = [datePicker date];
	} else {
		self.dateTwo = [datePicker date];
	}			   
}

Please read up on Cocoa memory management. It's clear you don't follow what you are required to do when you take ownership of an object.

 

[Buschmaster]

You code makes no sense.

I have annotated it with comments:

-(void) pickerChangedDate:(id)sender {
	if([segmentedControl selectedSegmentIndex] == 0) {
		NSDate *aDate = [[NSDate alloc] init];
                // This is an error: why are you creating an object (alloc/init pair)
                // when you then set the variable to another date in the next
                // line.  This will leak memory.
		aDate = [datePicker date];
		dateOne = aDate;
                // Where to you retain aDate?
                // You've date dateOne to point at it, but as it's autoreleased it
                // will get dealloced real soon.  If you use dateOne after that
                // you will crash.
                // Also if dateOne is a property you are doing it all wrong: you
                // need to either use the date syntax or the setter directly
                // otherwise any existing object pointed to by dateOne will not
                // get released and you will leak more memory
		[aDate release];
                // Why are you releasing this date?
                // The date from datePicker will be autoreleased.  You should not release it.
	} else {
		NSDate *aDate = [[NSDate alloc] init];
		aDate = [datePicker date];
		dateTwo = aDate;
		[aDate release];
	}			   
}

Corrected code (assumes dateOne and dateTwo are properties with synthesized accessor/setter methods)

-(void) pickerChangedDate:(id)sender {
	if([segmentedControl selectedSegmentIndex] == 0) {
		self.dateOne = [datePicker date];
	} else {
		self.dateTwo = [datePicker date];
	}			   
}

Please read up on Cocoa memory management. It's clear you don't follow what you are required to do when you take ownership of an object.

Thanks for the help. I could've sworn I had tried that earlier and it was a no-go. That's why I was trying to create another object and set it as that.

Would the use of self.dateOne rather than just dateOne have made a big difference?

 

[PhoneyDeveloper]

Would the use of self.dateOne rather than just dateOne have made a big difference?

Of course. That's why you need to read the memory management documentation and the properties section in the ObjC-2.0 docs.

You shouldn't cross-post your questions to more than one list. That is rude.

 

[robbieduncan]

Thanks for the help. I could've sworn I had tried that earlier and it was a no-go. That's why I was trying to create another object and set it as that.

Would the use of self.dateOne rather than just dateOne have made a big difference?

Yes, this calls the synthesized setter that will retain the object and release any existing object value for this property.