I recommend reading and doing the exercises in a basic programming book first (any language, but there are tons of beginner books on C or Java). If you aren't familiar with control structures, data types, pointers, objects, simple algorithms, debugging, memory & performance constraints, etc., you can easily start coding yourself into a blind alley, and just end up with a pile of frustration.
If you already know the above, then sure, jump right into Apple's tutorials, they're quite good.
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