A very simple implementation of vector operations in Apple's SpriteKit.
SpriteKit vector operations largely relay on the types CGVector and CGPoint.
Method names are relatively self explanatory. addVectors: and subtractVectors: work as expected, with order of subtraction occuring in the order the vectors are passed.
sumArray: will return the vector sum of an NSArray of vectors.
magnitude: will return a float magnitude of the passed vector.
Simply
#import VectorMath.h
And you should be all set.