接下来是工作代码，可让您维护与主“键”（此处为电子邮件地址，可以是应用中的任何主标识符）相关联的数据字典。
其他键存储在任意大小的字典中，并放置在“密码”keyChain 对象中。
首先，我把它放在我的 AppDelegate.h 文件的底部：
#define kEmail @"email"
#define kPassword @"pass"
#define kSomeOtherItemA @"a_item"
#define kSomeOtherItemB @"b_item"
@interface AppDelegate (Keychain)
- (NSDictionary *)keychainDictionary; // current keyChain dictionary
- (void)eraseKeychain; // total wipe it
- (void)erasePassword; // wipe the password
@end
您可以在此处添加您认为合适的特殊方法。通过放置这是 AppDelegate.h 文件，导入该文件的任何其他类都可以使用这些方法。如果您希望它私有，请将其移至您的 AppDelegate.m 文件
这在您的 AppDelegate.m 文件中，在顶部：
@interface AppDelegate (KeychainPrivate)
- (void)updateKeychainItem:(NSString *)item forKey:(NSString *)key; //the password, or itemA, or itemB
- (id)keychainItemForKey:(NSString *)key; // the password, itemA, itemB, ...
@end
这可以放在 AppDelegate.m 的底部或单独的文件中：
static char *kcIdentifier = "foo"; // use any string you want instead of "foo"
@implementation AppDelegate (Keychain)
- (KeychainItemWrapper *)keyChainItemWrapper
{
static dispatch_once_t pred;
static KeychainItemWrapper *kciw;
dispatch_once(&pred, ^
{
kciw = [[KeychainItemWrapper alloc] initWithIdentifier:kcIdentifier accessGroup:nil];
} );
return kciw;
}
- (NSDictionary *)keychainDictionary
{
NSMutableDictionary *mDict = [NSMutableDictionary dictionaryWithCapacity:3];
KeychainItemWrapper *kcItem = [self keyChainItemWrapper];
NSString *emailAddr = [kcItem objectForKey:(__bridge id)kSecAttrAccount];
if([emailAddr length]) {
NSData *data = [kcItem objectForKey:(__bridge id)kSecValueData];
if([data length]) {
NSKeyedUnarchiver *kua = [[NSKeyedUnarchiver alloc] initForReadingWithData:data];
NSDictionary *dict = [kua decodeObject];
[kua finishDecoding];
[mDict addEntriesFromDictionary:dict];
}
mDict[kEmail] = emailAddr; // last in case it got in the dictionary somehow
}
return mDict;
}
- (void)eraseKeychain
{
KeychainItemWrapper *kcItem = [self keyChainItemWrapper];
[kcItem resetKeychainItem];
}
- (void)erasePassword
{
[self updateKeychainItem:@"" forKey:kPassword];
}
@end
@implementation AppDelegate (KeychainPrivate)
- (void)updateKeychainItem:(NSString *)item forKey:(NSString *)key
{
KeychainItemWrapper *kcItem = [self keyChainItemWrapper];
// NSLog(@"SET KC key=%@ ITEM %@", key, item);
// NSLog(@"CURRENT KEYCHAIN: %@", [self keychainDictionary]);
if([key isEqualToString:kEmail]) {
NSString *emailAddr = [kcItem objectForKey:(__bridge id)kSecAttrAccount];
if(![emailAddr isEqualToString:item]) {
[kcItem setObject:item forKey:(__bridge id)kSecAttrAccount];
// NSLog(@"SET KC Account ITEM %@", item);
}
// NSLog(@"KC Account ITEM %@ ALREADY SET", item);
} else {
NSData *data = [kcItem objectForKey:(__bridge id)kSecValueData];
//NSLog(@"KC get DATA len=%d", [data length]);
NSDictionary *dict;
if([data length]) {
NSKeyedUnarchiver *kua = [[NSKeyedUnarchiver alloc] initForReadingWithData:data];
dict = [kua decodeObject];
[kua finishDecoding];
} else {
dict = [NSDictionary dictionary];
}
//NSLog(@"KC OLD DICT %@", dict);
if(![item isEqualToString:dict[key]]) {
//NSLog(@"KC DATA NOT EQUAL");
NSMutableDictionary *mDict = [NSMutableDictionary dictionaryWithDictionary:dict];
mDict[key] = item;
NSMutableData *tmpData = [NSMutableData dataWithCapacity:256];
NSKeyedArchiver *ka = [[NSKeyedArchiver alloc] initForWritingWithMutableData:tmpData];
[ka encodeObject:mDict];
[ka finishEncoding];
//NSLog(@"KC ENCODE MDICT %@", mDict);
[kcItem setObject:tmpData forKey:(__bridge id)kSecValueData];
//NSLog(@"SET KC DATA LEN=%d", [tmpData length]);
}
}
//NSLog(@"JUST UPDATED KEYCHAIN KEY=%@ val=%@ read dict back=%@", key, item, [self keychainDictionary]);
}
- (id)keychainItemForKey:(NSString *)key
{
NSDictionary *dict = [self keychainDictionary];
return dict[key];
}
@end
您还需要 KeyChainItemWrapper 类。你可以得到一个 ARCified 并稍作修改（以便处理字典）KeyChainItemWrapper version。您真的可以使用任何您想要的 KeyChainWrapper 文件，但需要进行此更改（这是除 ARCifying 之外对 Apple 代码的唯一更改）：
// Default data for keychain item.
#ifndef PASSWORD_USES_DATA
[keychainItemData setObject:@"" forKey:(__bridge id)kSecValueData];
#else
[keychainItemData setObject:[NSData data] forKey:(__bridge id)kSecValueData];
#endif
如您所见，如果您愿意，可以取消注释很多日志消息以查看它的运行情况。
此代码用于运输应用程序。