时区“ ZE8”的问题，如何将NSDate转换为NSString

Question

How to convert (12/27/2013 05:49:41 PM ZE8) NSString to NSDate?

NSString *string = @"12/27/2013 05:49:41 PM ZE8";
NSDateFormatter *formatter = [NSDateFormatter new];
[formatter setDateFormat:@"MM/dd/yyyy HH:mm:ss a z"];
NSDate *publishDate = [formatter dateFromString:string];

publishDate is getting null value. What is issue that?

Answer 1

The problem appears because ZE8 format is NOT valid format for timezones in unix systems!

You can use:

• Localized GMT strings (and variance of that)
• RFC 822 GMT
• even Generic location format

But ZE8 is invalid

You have to convert this data to valid one, so you have to add another Array/table/dictionary what do you like with this values http://www.ibm.com/developerworks/lotus/library/ls-keeping_time/side1.html and convert it to RFC 822 for example

No, there is no built in way - you have to write this structure by yourself. For example using dictionary (if i were you i will write a category by myself). I write a simple solution for you, of course if you do this often you should keep this dictionary somewhere and also write all the values from above page (i write only two):

-(void)myBaseMethod {
    NSDate *finalDate = [self convertStringToDate:@"12/27/2013 05:49:41 PM ZE8"];
}

-(NSDate*)convertStringToDate:(NSString*)str {
    NSDateFormatter *formatter = [NSDateFormatter new];
    [formatter setDateFormat:@"MM/dd/yyyy HH:mm:ss a z"];
    return [formatter dateFromString:[self changeTimeZoneToValidOneFromString:str]];
}

-(NSString*)changeTimeZoneToValidOneFromString:(NSString*)inputStrDate {
    NSDictionary *timeZonesDic = [NSDictionary dictionaryWithObjectsAndKeys:
                                  @"GMT-08:00",@"ZE8",
                                  @"GMT-7:00",@"ZE7",
                                  nil];
    NSMutableArray *dateItems = [[inputStrDate componentsSeparatedByString:@" "] mutableCopy]; //in here I break the original string into array of strings (every element is separate date component)
    NSString *timeZoneString = [timeZonesDic objectForKey:[dateItems lastObject]]; //convert using dictionary
    [dateItems replaceObjectAtIndex:([dateItems count]-1) withObject:timeZoneString]; //replacing the last object of the existing array.
    return [dateItems componentsJoinedByString:@" "]; //in here I join it back together
}

Really make a Category ( NSDate ) for it, then you will be call only convertStringToDate: method and the rest will be in one place.

Hope this will help you.

Answer 2

Try

NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:@"yyyy"];

//Optionally for time zone converstions
[formatter setTimeZone:[NSTimeZone timeZoneWithName:@"..."]];

NSString *stringFromDate = [formatter stringFromDate:myNSDateInstance];

[formatter release];

All the best