A CLLocation category for determing the time zone from a location.

CLLocation+rhextensions.h

//
//  CLLocation+rhextensions.h
//
//  Copyright (C) 2015 by Christopher Meyer
//  http://schwiiz.org/
//
//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the Software is
//  furnished to do so, subject to the following conditions:
//
//  The above copyright notice and this permission notice shall be included in
//  all copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
//  THE SOFTWARE.
//

#import <CoreLocation/CoreLocation.h>

@interface CLLocation (rhextensions)

-(id)initWithCoordinates:(CLLocationCoordinate2D)coordinates;
-(void)timeZoneWithBlock:(void (^)(NSTimeZone *timezone))block;

@end

CLLocation+rhextensions.m

//
//  CLLocation+rhextensions.m
//
//  Copyright (C) 2015 by Christopher Meyer
//  http://schwiiz.org/
//
//  Permission is hereby granted, free of charge, to any person obtaining a copy
//  of this software and associated documentation files (the "Software"), to deal
//  in the Software without restriction, including without limitation the rights
//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the Software is
//  furnished to do so, subject to the following conditions:
//
//  The above copyright notice and this permission notice shall be included in
//  all copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
//  THE SOFTWARE.
//

#import "CLLocation+rhextensions.h"

@implementation CLLocation (rhextensions)

-(id)initWithCoordinates:(CLLocationCoordinate2D)coordinates {
    return [self initWithLatitude:coordinates.latitude longitude:coordinates.longitude];
}

-(void)timeZoneWithBlock:(void (^)(NSTimeZone *timezone))block {
    
    [[[CLGeocoder alloc] init] reverseGeocodeLocation:self completionHandler:^(NSArray *placemarks, NSError *error) {
        
        NSTimeZone *timeZone = nil;
        
        if (error == nil && [placemarks count] > 0) {
            CLPlacemark *placeMark = [placemarks firstObject];
            timeZone = placeMark.timeZone;
        }
        
        block(timeZone);       
    }];
}

@end

This fails for timezone "Asia/Ho_Chi_Minh"

Try this instead:
@"identifier = "(.*?)""