How to reference environment specific iOS Enviroment Variables. Followed this example, and updated to reflect ARC usuage. http://blog.carbonfive.com/2011/06/20/managing-ios-configurations-per-environment-in-xcode-4/

env.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
  <key>Release</key>
	<dict/>
	<key>Debug</key>
	<dict>
		<key>apiUrl</key>
		<string>http://localhost:3000/api/v1/</string>
	</dict>
</dict>
</plist>

Environment.h

//
//  Environment.h
//  Visible
//
//  Created by weston on 9/4/13.
//  Copyright (c) 2013 Visible. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface Environment : NSObject

@property (nonatomic, strong) NSString *apiUrl;

+ (Environment *)sharedInstance;

@end

Environment.m

//
//  Environment.m
//  Visible
//
//  Created by weston on 9/4/13.
//  Copyright (c) 2013 Visible. All rights reserved.
//

#import "Environment.h"

@implementation Environment

static Environment *sharedInstance = nil;

- (id)init
{
    self = [super init];
    return self;
}

- (void)initializeSharedInstance
{
    NSString* configuration = [[[NSBundle mainBundle] infoDictionary] objectForKey:@"Configuration"];
    NSBundle* bundle = [NSBundle mainBundle];
    NSString* envsPListPath = [bundle pathForResource:@"env" ofType:@"plist"];
    NSDictionary* environments = [[NSDictionary alloc] initWithContentsOfFile:envsPListPath];
    NSDictionary* environment = [environments objectForKey:configuration];
    
    _apiUrl = [environment valueForKey:@"apiUrl"];
}

#pragma mark - Lifecycle Methods

+ (Environment *)sharedInstance
{
    @synchronized(self) {
        if (sharedInstance == nil) {
            sharedInstance = [[self alloc] init];
            [sharedInstance initializeSharedInstance];
        }
        return sharedInstance;
    }
}

@end

LoginViewController.m

//
//  LoginViewController.m
//  Visible
//
//  Created by weston on 9/4/13.
//  Copyright (c) 2013 Visible. All rights reserved.
//

#import "LoginViewController.h"

#import "Environment.h"

@implementation LoginViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    [self authenticate];
}

- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
}

- (void)authenticate {
    
    Environment *env = [Environment sharedInstance];
    NSString *apiUrl = env.apiUrl;
    
    NSLog(@"apiUrl = %@", apiUrl);
}

@end

Visible-Info.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
	<key>Configuration</key>
	<string>${CONFIGURATION}</string>
</dict>
</plist>