How do I convert from NSString to NSDate?

问题:

how to convert from NSString to NSDate ?

it must be in yyyy-MM-dd HH:mm:ss this format when it converts from NSString to NSDate format

回答1:

Use NSDateFormatter's dateFromString:

NSString *dateStr = @"20100212";

// Convert string to date object
NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
[dateFormat setDateFormat:@"yyyyMMdd"];
NSDate *date = [dateFormat dateFromString:dateStr];  

// Convert date object to desired output format
[dateFormat setDateFormat:@"YYYY-MM-dd HH:mm:ss"];
dateStr = [dateFormat stringFromDate:date];  
[dateFormat release];

回答2:

For further ref. Check out:

http://developer.apple.com/mac/library/documentation/Cocoa/Conceptual/DataFormatting/Articles/dfDateFormatting10_4.html#//apple_ref/doc/uid/TP40002369-SW1

回答3:

Made an NSString extension for that.

// Simple as this.   
date = dateString.dateValue;

Thanks to NSDataDetector, it recognizes a whole lot of format.

// Tested in GMT+1 (Hungary).
@"2014-01-16" dateValue is <2014-01-16 11:00:00 +0000>
@"2014.01.16" dateValue is <2014-01-16 11:00:00 +0000>
@"2014/01/16" dateValue is <2014-01-16 11:00:00 +0000>
@"2014 Jan 16" dateValue is <2014-01-16 11:00:00 +0000>
@"2014 Jan 16th" dateValue is <2014-01-16 11:00:00 +0000>
@"20140116" dateValue is <2014-01-16 11:00:00 +0000>
@"01-16-2014" dateValue is <2014-01-16 11:00:00 +0000>
@"01.16.2014" dateValue is <2014-01-16 11:00:00 +0000>
@"01/16/2014" dateValue is <2014-01-16 11:00:00 +0000>
@"16 January 2014" dateValue is <2014-01-16 11:00:00 +0000>
@"01-16-2014 17:05:05" dateValue is <2014-01-16 16:05:05 +0000>
@"01-16-2014 T 17:05:05 UTC" dateValue is <2014-01-16 17:05:05 +0000>
@"17:05, 1 January 2014 (UTC)" dateValue is <2014-01-01 16:05:00 +0000>

Part of eppz!kit, grab the category NSString+EPPZKit.h from GitHub.