There’s an awful lot of economic theory being banded about here, but I’m not sure it considers the full picture. Defending Apple for price rises citing currency fluctuations is a little short sighted. Yes, like all multinational companies Apple is exposed to a good deal of foreign exchange rate risk. How it deals with this risk is a strategy choice. There are multiple options available from use of financial instruments for hedging such as options and futures, to moving liquid funds abroad and relying on interest rate parity. There is also the option, should margins allow, to simply accept the risk and take reduced profits. The one Apple chooses is to transfer the risk to their customers. The benefit of this approach is that it costs Apple nothing, and all other approaches would have some form of cost attached. The drawback is that it affects demand. If you raise the price of a product, a proportion of your potential customers will either no longer be able to afford it or will believe that it no longer represents good value, and will not buy it. This will reduce your sales volume so, even though your margins remain the same or greater, your actual profits can fall. Apple clearly believes that any reduction in profits from decreased demand will be lower than the cost of dealing with the exchange rate risk themselves.
If in times of inflation salaries also increase, people will be more likely to accept the higher prices. From the point of view of the consumer, the majority of us in the UK have not seen our salaries increase at all. As a result, an iPad which once cost x times our disposable income now costs 1.2x times our disposable income, yet we see no tangible increase in the value of the goods being transferred to us. That is why these price increases are so difficult to swallow. The fact that it is being done at a time when people are least able to afford such an increase due to increased gas and electricity bills makes it feel like Apple are out of touch with their customer base and will lose them a good deal of goodwill.
As an aside, it is a fallacy to talk about inflation and exchange rate fluctuations as if they are two separate things. They are inextricably linked - differing rates of inflation in differing countries drive a change in the relative values of their currency, and hence cause exchange rate fluctuations.