Is this a correct way to write a convenience constructor?
Personally I would prefer the second option because it makes it easier/less weird for subclasses to use and override alloc-init.

As a side node I would point to some reasons to reconsider user properties in your constructors. 


Should I refer to self.property in the init method with ARC?
Friday Q&amp;A 2009-11-27: Using Accessors in Init and Dealloc
Don’t Message self in Objective-C init (or dealloc)