what is difference between alloc and allocWithZone:?

Question

From forum discussion , seem like that the big difference is performance factor, allocWithZone: will alloc memory from particular memory area, which reduce cost of swapping.

Answer 1

In the Foundation Functions Reference, all of the Zone functions are now prefaced with the below warning that Zones will be ignored.

Zones are ignored on iOS and 64-bit runtime on OS X. You should not use zones in current development.

NSCreateZone
NSRecycleZone
NSSetZoneName
NSZoneCalloc
NSZoneFree
NSZoneFromPointer
NSZoneMalloc
NSZoneName
NSZoneRealloc
NSDefaultMallocZone