Question

i have an array of some values that i use in a mathematical formula, and i want to know which is the better data structure(NSArray or NSDictionary or …) to use? Thanks.

Answer 1

Any reason for not using NS(Mutable)Dictionary (NSNumber/NSString) as key / value?

You can try some thing like this:

XYPair:NSObject<NSCoding,NSCopying>
{
NSNumber *xValue;
NSNumber *yValue;
}

let the initializer be some thing like,
-(id) initWithXValue:(NSNumber*)x YValue:(NSNumber)y;

Usage:
XYPair *someEntry = [XYPair alloc] initWithXValue:[NSNumber numberWithInt:1000] YValue:[NSNumber numberWithInt:0.25]];
NSMutableDictionary *ds = [NSMutableDictionary alloc] initWithObjects:someEntry,@"1",nil];

Dont forget to implement NSCoding (requried for archiving),NSCopying(in order to qualify to be a valid key) for XYPair