JNKeychain.m

//
//  JNKeychain.m
//
//  Created by Jeremias Nunez on 5/10/13.
//  Copyright (c) 2013 Jeremias Nunez. All rights reserved.
//
//  jeremias.np@gmail.com

#import "JNKeychain.h"

@interface JNKeychain ()

+ (NSMutableDictionary *)getKeychainQuery:(NSString *)key;

@end

@implementation JNKeychain

+ (NSMutableDictionary *)getKeychainQuery:(NSString *)key
{
    // see http://developer.apple.com/library/ios/#DOCUMENTATION/Security/Reference/keychainservices/Reference/reference.html 
    return [NSMutableDictionary dictionaryWithObjectsAndKeys:
            (__bridge id)kSecClassGenericPassword, (__bridge id)kSecClass,
            key, (__bridge id)kSecAttrService,
            key, (__bridge id)kSecAttrAccount,
            (__bridge id)kSecAttrAccessibleAfterFirstUnlock, (__bridge id)kSecAttrAccessible,
            nil];
}

+ (void)saveValue:(id)data forKey:(NSString*)key
{
    NSMutableDictionary *keychainQuery = [self getKeychainQuery:key];
    // delete any previous value with this key
    SecItemDelete((__bridge CFDictionaryRef)keychainQuery);
    
    [keychainQuery setObject:[NSKeyedArchiver archivedDataWithRootObject:data] forKey:(__bridge id)kSecValueData];
    
    SecItemAdd((__bridge CFDictionaryRef)keychainQuery, NULL);
}

+ (id)loadValueForKey:(NSString *)key
{
    id value = nil;
    NSMutableDictionary *keychainQuery = [self getKeychainQuery:key];
    CFDataRef keyData = NULL;
    
    [keychainQuery setObject:(__bridge id)kCFBooleanTrue forKey:(__bridge id)kSecReturnData];
    [keychainQuery setObject:(__bridge id)kSecMatchLimitOne forKey:(__bridge id)kSecMatchLimit];
    
    if (SecItemCopyMatching((__bridge CFDictionaryRef)keychainQuery, (CFTypeRef *)&keyData) == noErr) {
        @try {
            value = [NSKeyedUnarchiver unarchiveObjectWithData:(__bridge NSData *)keyData];
        }
        @catch (NSException *e) {
            NSLog(@"Unarchive of %@ failed: %@", key, e);
        }
        @finally {}
    }
    
    if (keyData) {
        CFRelease(keyData);
    }
    
    return value;
}

+ (void)deleteValueForKey:(NSString *)key
{
    NSMutableDictionary *keychainQuery = [self getKeychainQuery:key];
    SecItemDelete((__bridge CFDictionaryRef)keychainQuery);
}

@end