Quindi mi sono guardato attorno e non ho potuto trovare una risposta a questo.
Ho un iPhone (jailbroke) e noto in più impostazioni che c'è una stringa di solito nei file .plist che dice qualcosa di simile a "TimeIntervalSince1970". Ora so che tutti i timer di questo tipo hanno bisogno di una data e un'ora di partenza.
Ma la mia vera domanda è perché 1970?
Non tutto conta dal 1970. È il tempo standard di Unix.
Unix time, or POSIX time, is a system for describing points in time, defined as the number of seconds elapsed since midnight proleptic Coordinated Universal Time (UTC) of January 1, 1970, not counting leap seconds.
Early versions of unix measured system time in 1/60 s intervals. This meant that a 32-bit unsigned integer could only represent a span of time less than 829 days. For this reason, the time represented by the number 0 (called the epoch) had to be set in the very recent past. As this was in the early 1970s, the epoch was set to 1971-1-1.
Later, the system time was changed to increment every second, which increased the span of time that could be represented by a 32-bit unsigned integer to around 136 years. As it was no longer so important to squeeze every second out of the counter, the epoch was rounded down to the nearest decade, thus becoming 1970-1-1. One must assume that this was considered a bit neater than 1971-1-1.
Note that a 32-bit signed integer using 1970-1-1 as its epoch can represent dates up to 2038-1-19, on which date it will wrap around to 1901-12-13.
Il timestamp Unix inizia il 1 ° gennaio 1970 e conta da allora. Il tempo in termini di giorni / mesi / anni / ecc è calcolato da questo numero, tenendo conto dei fusi orari e di altre differenze regionali.