Green’s Dictionary of Slang

apples adj.

[apple-pie order n. or rhy. sl. apples and spice adj.; although primarily assoc. with Aus., apples is used by the residents of Brooklyn, New York, to mean the same thing]

(Aus./N.Z.) satisfactory, as required; esp. in phr. she’ll be apples, it will be fine.

[[US]G.W. Harris ‘Epistle from Tennessee’ Spirit of the Times (N.Y.) XII Jan. in Inge (1967) 15: I am in good health, or, in other words, ‘in town with a shirt full of apples’].
[Aus]J. Binning Target Area 140: If everything is running smoothly ‘she’s apples.’.
[Aus]T.A.G. Hungerford Riverslake 131: ‘You be O.K., you think?’ [...] ‘Hell, yes, she’s apples.’.
[Aus]B. Humphries Barry McKenzie [comic strip] in Complete Barry McKenzie (1988) 29: He’s apples! Just a bit full Phil! [Ibid.] 31: There, there, mum — she’ll be apples.
[Aus]D. Ireland Glass Canoe (1982) 186: If she does she does. If she doesn’t, she’s still apples.
[Aus]R. Aven-Bray Ridgey-Didge Oz Jack Lang 10: Nah, she’s apples china, I’d rather prop on me Pat Malone. I’m only in for a quick gargle.
[NZ]McGill Dict. of Kiwi Sl. 10/2: apples in good condition, in phr. she’s apples, indicative of apple pie order; possibly contraction of rhyming slang: ‘apple and pear/fair’. NZA .
[Aus]Penguin Bk of More Aus. Jokes 355: The barman suggested that he might need to go to the toilet. ‘Nah, I’ll be apples. Pour me a few more.’ And he continued to drink, showing not the slightest desire to point Percy at the porcelain.
[NZ]McGill Reed Dict. of N.Z. Sl. [as cit. 1988].