Basically a calendar is long volatility (because of the long option is back-month, and the short option is fron-month); and if AAPL goes up, volatility will likely go down.
In stocks calendars work best when you are predicting a move DOWN (because a move down tends to increase vol). I stocks butterflies work best when you are predicting a move UP (because a move up tends to decrease vol). It can be different in commodities, though, and that is reflected in the skew.
I tend to agree with the last comments... A calendar is not a bullish play... Its good when volatility is low and price high. What the OP was looking at is def a buy-write with options. I also like flies as some have mentioned, specifically with puts, if established for a net credit. I like them because they give you a lot of chances to adjust on the downside because of the spike that is actually lower than your starting point.