YPFastDateParser

An efficient API for parsing string dates, times, and timestamps into NSDate objects.

This API leverages the speed of SQLite's date parsing, resulting in a speed improvement of ~2 orders of magnitude over NSDateFormatter. In addition, it accomodates some common date formats that SQLite does not directly support.

Based on ideas from (http://vombat.tumblr.com/post/60530544401/date-parsing-performance-on-ios-nsdateformatter-vs)

The API

NSDate *date = [YPFastDateParser dateFromString:@""];

Returns nil if the string cannot be parsed into a date.

Date Formats

yyyy-mm-dd
yyyy-mm-dd hh:mm
yyyy-mm-dd hh:mm:ss
yyyy-mm-dd hh:mm:ss.SSS

yyyy-mm-ddThh:mm          // Note the literal 'T'
yyyy-mm-ddThh:mm:ss
yyyy-mm-ddThh:mm:ss.SSS

hh:mm
hh:mm:ss
hh:mm:ss.SSS

'now'                     // Literal string
DDDDDDDDDD                // Julian day number as a float

Note: Fractional seconds (.SSS) may contain an arbitrary number of digits. However, only the first three digits are significant to the result; additional digits are ignored.

Time Zone Specifiers

A time zone specifier may be appended to any of the supported date formats.

The following formats are supported natively by SQLite and provide optimal efficiency:

Z         // GMT
+00:00    // Hours and minutes offset

The following formats are supported by the API but incur a performance penalty:

+00       // ~1.3x base speed
+01       // Non-zero offset, ~3x base speed
+0000     // ~4x base speed

Thread Safety

This API is not thread-safe (yet).

If you are using this API across multiple threads, you are strongly advised to create a separate instance of the parser for each thread:

YPFastDateParser *fastParser = [YPFastDateParser new];
NSDate *date = [fastParser dateFromString:aString];