For the iPhone, or any iOS device, I recommend you consider the app: "Spanish Dictionary, Translator, Phrase Book" by iThinkdiff. It is available at the iTunes App store.
There is a free version, and another costing a small amount. I recommend the pay version as it has more features.
Also, this is one of a complete line of similar products for many different languages. I have a copy of the app in every language I encounter while globetrotting. I even used the Portuguese version on Camino in 2015, until I discovered that many Portuguese speak good English (subtitled English programming on TV). However, my French, Italian, and Spanish versions are used regularly, once I determine that English is not an option.
This app offers an excellent offline dictionary and phrase book, plus the ability to bookmark select words. The translator function is only available with a data / Wi-Fi connection but is very good. You can save the results of the online translations in your offline bookmark file. This makes it handy for saving favorite phrases, such as, "Can you please call me a taxi, for now?"
Or, one of my personal favorites: "My feet smell like cheese even when I wash them well with soap and water. Do I have a fungus infection? Do you have anything for it?" THAT was a classic on my first Camino. I now know what to ask for at a farmacia, if I suffer the results of forgetting to wear flip-flops in any shower or tub.
If you have a Wi-Fi connection, the translator, or bookmarked phrases, can be spoken aloud by your device as well. I have not tried this offline. But, logically it should work. Then again, I do not use Siri...so who knows?
So, you can brainstem-storm all the various phrases you think you might need, translate them, and save them. That is what I do. I also store them in my cloud account, so I can fetch them online.
I hope this helps.