方法一：
今天在做聯網版本的離線操作時，需要使用本地驗證密碼和用戶名，然后就發現了這個keychain方法。可以很快捷的存儲和讀取你要的東西。下面我們來一起簡單的應用它一下吧！
學習地址：http://www.lvtao.net/ios/ios-keychain.html
ios的keychain服務提供了一種安全的保存私密信息（密碼，序列號，證書等）的方式。每個ios程序都有一個獨立的keychain存儲。從ios 3.0開始，跨程序分享keychain變得可行。
下面就使用keychain來實現存取用戶名和密碼。
蘋果已經有現成的類封裝好了keychain,KeychainItemWrapper.h和KeychainItemWrapper.m文件,可以在GenericKeychain實例里找到。
但是這里我只需要存取用戶名和密碼，就不用蘋果提供的類了，自己寫個簡單的類來實現就好。
代碼如下：
CHKeychain.h
#import
#import
@interface CHKeychain : NSObject
+ (void)save:(NSString *)service data:(id)data;
+ (id)load:(NSString *)service;
+ (void)delete:(NSString *)service;
@end
CHKeychain.m
#import "CHKeychain.h"
@implementation CHKeychain
+ (NSMutableDictionary *)getKeychainQuery:(NSString *)service {
return [NSMutableDictionary dictionaryWithObjectsAndKeys:
(id)kSecClassGenericPassword,(id)kSecClass,
service, (id)kSecAttrService,
service, (id)kSecAttrAccount,
(id)kSecAttrAccessibleAfterFirstUnlock,(id)kSecAttrAccessible,
nil];
}
+ (void)save:(NSString *)service data:(id)data {
//Get search dictionary
NSMutableDictionary *keychainQuery = [self getKeychainQuery:service];
//Delete old item before add new item
SecItemDelete((CFDictionaryRef)keychainQuery);
//Add new object to search dictionary(Attention:the data format)
[keychainQuery setObject:[NSKeyedArchiver archivedDataWithRootObject:data] forKey:(id)kSecValueData];
//Add item to keychain with the search dictionary
SecItemAdd((CFDictionaryRef)keychainQuery, NULL);
}
+ (id)load:(NSString *)service {
id ret = nil;
NSMutableDictionary *keychainQuery = [self getKeychainQuery:service];
//Configure the search setting
//Since in our simple case we are expecting only a single attribute to be returned (the password) we can set the attribute kSecReturnData to kCFBooleanTrue
[keychainQuery setObject:(id)kCFBooleanTrue forKey:(id)kSecReturnData];
[keychainQuery setObject:(id)kSecMatchLimitOne forKey:(id)kSecMatchLimit];
CFDataRef keyData = NULL;
if (SecItemCopyMatching((CFDictionaryRef)keychainQuery, (CFTypeRef *)&keyData) == noErr) {
@try {
ret = [NSKeyedUnarchiver unarchiveObjectWithData:(NSData *)keyData];
} @catch (NSException *e) {
NSLog(@"Unarchive of %@ failed: %@", service, e);
} @finally {
}
}
if (keyData)
CFRelease(keyData);
return ret;
}
+ (void)delete:(NSString *)service {
NSMutableDictionary *keychainQuery = [self getKeychainQuery:service];
SecItemDelete((CFDictionaryRef)keychainQuery);
}
@end
首先需要定義幾個字符串用來做key：
NSString * const KEY_USERNAME_PASSWORD = @"com.company.app.usernamepassword";
NSString * const KEY_USERNAME = @"com.company.app.username";
NSString * const KEY_PASSWORD = @"com.company.app.password";
把用戶名和密碼存入keychain：
NSMutableDictionary *usernamepasswordKVPairs = [NSMutableDictionary dictionary];
[usernamepasswordKVPairs setObject:txtfldUsername.text forKey:KEY_USERNAME];
[usernamepasswordKVPairs setObject:txtfldPassword.text forKey:KEY_PASSWORD];
[CHKeychain save:KEY_USERNAME_PASSWORD data:usernamepasswordKVPairs];
從keychain中取出用戶名和密碼：
NSMutableDictionary *usernamepasswordKVPairs = (NSMutableDictionary *)[CHKeychain load:KEY_USERNAME_PASSWORD];
txtfldUsername.text = [usernamepasswordKVPairs objectForKey:KEY_USERNAME];
txtfldPassword.text = [usernamepasswordKVPairs objectForKey:KEY_PASSWORD];
刪除一個keychain item:
[CHKeychain delete:KEY_USERNAME_PASSWORD];
這樣一個簡單的使用keychain存取用戶名密碼的功能就做好了。
方法二：
使用沙盒保存信息
這個方法相對于上個方法，更加簡單，快捷，也不需要去建立一個類。直接保存取出就OK咯。
//取出保存好的名稱和密碼
_userNameTF.text = [[NSUserDefaults standardUserDefaults] objectForKey:kUserName];
_passWordTF.text = [[NSUserDefaults standardUserDefaults] objectForKey:kPassWd];
[[NSUserDefaults standardUserDefaults] synchronize];
//保存需要保存的名稱和密碼
[[NSUserDefaults standardUserDefaults] setObject:_userNameTF.text forKey:kUserName];
[[NSUserDefaults standardUserDefaults] setObject:_passWordTF.text forKey:kPassWd];
[[NSUserDefaults standardUserDefaults] synchronize];
