How to store CGRect and other things in core data

Question

I'm having a few teething problems with coredata, but feel it would clear things up for me greatly if someone could explain some simple cases to me.

I want to put my model into coredata, and at a most simple case take advantage of undo/redo. Thing is, all the examples I see tend to store either strings or integers. What if I have a class as follows that I wanted to implement in core data (a made up example):

@interface Badge : NSObject {

NSString *textForBadge;
int      badgeValue;
UIColor  *color;
CGRect    rect;
NSMutableArray *awards; // this would be a list of 'Category' - another custom class
}

These are all made up on the spot, but each highlight a confusion

As I see it, I would open the .xcdatamodel and add a new Entity caled 'Badge', which would be an NSManagedObject. I then add a property for textForBadge of type String. So far so good. I do somthing similar for badgeValue, but then come to the UIColor and CGRect and I'm a bit stumped, since there isn't a property for those. Am I supposed to create an entity to represent each (i.e a Rect entity that has four properties x,y,w,h) that are ints? Then populate a CGRect with these ints each time? Ditto for the UIColor?

Finally, I come to my list of awards. If these are a list of pointers to a number of objects representing an award they might contain an image, a colour, text etc. I assume that award would again be an entity I have to design and rather than Badge storing an array I would have a 1 to many relationship from it to the Award class.

Am I getting any of this right, or going in the compete opposite direction? All the examples I see operate on vanilla objects like String or int so want to make sure I have this right in my head before implementing a bunch of stuff.

Kind regards,

Bryn

Answer 1

You have to be careful if you use the NSStringFromCGRect serialization suggested by aegzorz. This doesn't work reliably for big numbers that get abbreviated in the NSString representation.

For example, this code

CGRect test1 = CGRectMake(CGFLOAT_MAX, CGFLOAT_MAX, CGFLOAT_MAX, CGFLOAT_MAX);
NSString* test1Str = NSStringFromCGRect(test1);
CGRect test2 = CGRectFromString(test1Str);
NSLog(@"test1: %f %f %f %f", test1.origin.x - CGFLOAT_MAX, test1.origin.y - CGFLOAT_MAX, test1.size.width - CGFLOAT_MAX, test1.size.height - CGFLOAT_MAX);
NSLog(@"test2: %f %f %f %f", test2.origin.x - CGFLOAT_MAX, test2.origin.y - CGFLOAT_MAX, test2.size.width - CGFLOAT_MAX, test2.size.height - CGFLOAT_MAX);

will output

test1: 0.000000 0.000000 0.000000 0.000000
test2: -344800963262078397207103271862272.000000 -344800963262078397207103271862272.000000 -344800963262078397207103271862272.000000 -344800963262078397207103271862272.000000

In my opinion it's better to store the four values separately.