You can purchase them in advance:
By internet PURCHASE HERE
Telephone + 34 858 880 990 (ES, EN,FR)
From Monday to Sunday 9am to 8pm. Not available in public holidays.
To visit the monuments you just need the "print at home" on paper or on your smartphone.
To use the tranportation, you need to collect the tickets in advance.
Granada cards available 3 calendar months in advance.
The date of visit to the Alhambra may coincide with the starting date of the GRANADA CARD, except for purchases starting on the current day.