Question

Basically, I have a custom NSObject with a lot of boolean variables. I would like to know if there is a way to modify these variables (from outside this class) without creating a property for each one. Is this possible? Thanks in advance!
Here is part of my object’s header:

@interface Polygons : NSObject {

//BOOL values for attributes
BOOL parallelogram;
BOOL rhombus;
BOOL square;

...

}

Answer 1

Use a bitmask to represent a set of related boolean properties. First, define an enum like so:

enum GeometryFlags {
    Parallelogram = 1 << 0,
    Rhombus       = 1 << 1,
    Square        = 1 << 2,

    // etc.
};

You can optionally provide a corresponding typedef statement:

typedef NSUInteger GeometryFlags;

Then you can define a property to allow outside callers to access the bitmask:

// In .h file:
@property (nonatomic) GeometryFlags geometryFlags;

// In .m file:
@synthesize geometryFlags = _geometryFlags;

Calling code can then access the property to get or set the bitfield. Note that you can use the bitwise OR operator to specify multiple values:

// Uses the property accessor to modify two values in the bitmask.
someObj.geometryFlags = Parallelogram | Rhombus;

EDIT

For more info on how to work with a bitmask, see the following:

How do those bitmasks actually work?

http://en.wikipedia.org/wiki/Mask_(computing)

http://en.wikipedia.org/wiki/Bitwise_operation