苹果本着为用户安全考虑的初衷导致UDID和Mac地址相继阵亡，IMEI也不例外，为了设备的唯一性，一代代开发者绞尽脑汁，后来KeyChain被他们瞄上了，终于可以继续判别社别的唯一性。
原理是利用UUID，有人说，UUID是非唯一的，很容易变化，对，没错，但是UUID绝对不会重复对吧？所以UUID我只需要获取一次，然后存入KeyChain，即使App被删除了，KeyChain中的UUID也不会被删除，如果你们公司有两款App，完全可以通过存入的key值读取出另一个App的UUID，做一些简单的交互。
具体的实现方法，网上有很多种方法，很少有全套的使用方法，博主这里重新总结了下：
先说说获取UUID的方法：
CFUUIDRef myUUID = CFUUIDCreate( nil ); CFStringRef uuidString = CFUUIDCreateString( nil, myUUID ); NSString * result = (NSString *)CFBridgingRelease(CFStringCreateCopy( NULL, uuidString));
关于实际的存储，都是属于套路的代码了，没什么可读性，直接贴出来了：
有两个管理类：
#import <Foundation/Foundation.h> @interface LHUUIDManager : NSObject +(void)saveUUID; //保存UUID +(id)readUUID; //获取UUID +(void)deleteUUID; //删除 @end #import "LHUUIDManager.h" #import "LHKeyChain.h" @implementation LHUUIDManager : NSObject static NSString * const KEY_IN_KEYCHAIN = @"KEY_IN_KEYCHAIN"; static NSString * const KEY_IN_UUID = @"KEY_IN_UUID"; +(void)saveUUID { NSMutableDictionary *myUUIDDic = [NSMutableDictionary dictionary]; [myUUIDDic setObject:[self creatUUID] forKey:KEY_IN_UUID]; [LHKeyChain save:KEY_IN_KEYCHAIN data:myUUIDDic]; } +(id)readUUID { NSMutableDictionary *myUUIDDic = (NSMutableDictionary *)[LHKeyChain read:KEY_IN_KEYCHAIN]; return [myUUIDDic objectForKey:KEY_IN_UUID]; } +(void)deleteUUID { [LHKeyChain lhDelete:KEY_IN_KEYCHAIN]; } +(NSString *)creatUUID { CFUUIDRef myUUID = CFUUIDCreate( nil ); CFStringRef uuidString = CFUUIDCreateString( nil, myUUID ); NSString * result = (NSString *)CFBridgingRelease(CFStringCreateCopy( NULL, uuidString)); return result; } @end
#import <Foundation/Foundation.h> @interface LHKeyChain : NSObject + (NSMutableDictionary *)getKeychain:(NSString *)keyChain ; + (void)save:(NSString *)keyChain data:(id)data; + (id)read:(NSString *)keyChain; + (void)lhDelete:(NSString *)keyChain; @end #import "LHKeyChain.h" @implementation LHKeyChain + (NSMutableDictionary *)getKeychain:(NSString *)keyChain { return [NSMutableDictionary dictionaryWithObjectsAndKeys: (__bridge_transfer id)kSecClassGenericPassword,(__bridge_transfer id)kSecClass, keyChain, (__bridge_transfer id)kSecAttrService, keyChain, (__bridge_transfer id)kSecAttrAccount, (__bridge_transfer id)kSecAttrAccessibleAfterFirstUnlock,(__bridge_transfer id)kSecAttrAccessible, nil]; } + (void)save:(NSString *)keyChain data:(id)data { //Get search dictionary NSMutableDictionary *keychainQuery = [self getKeychain:keyChain]; //Delete old item before add new item CFDictionaryRef aRef = (__bridge_retained CFDictionaryRef)keychainQuery; SecItemDelete(aRef); //Add new object to search dictionary(Attention:the data format) [keychainQuery setObject:[NSKeyedArchiver archivedDataWithRootObject:data] forKey:(__bridge_transfer id)kSecValueData]; //Add item to keychain with the search dictionary SecItemAdd(aRef, NULL); } + (id)read:(NSString *)keyChain { id ret = nil; NSMutableDictionary *keychainQuery = [self getKeychain:keyChain]; //Configure the search setting [keychainQuery setObject:(id)kCFBooleanTrue forKey:(__bridge_transfer id)kSecReturnData]; [keychainQuery setObject:(__bridge_transfer id)kSecMatchLimitOne forKey:(__bridge_transfer id)kSecMatchLimit]; CFDataRef keyData = NULL; if (SecItemCopyMatching((__bridge_retained CFDictionaryRef)keychainQuery, (CFTypeRef *)&keyData) == noErr) { @try { ret = [NSKeyedUnarchiver unarchiveObjectWithData:(__bridge_transfer NSData *)keyData]; } @catch (NSException *e) { NSLog(@"Unarchive of %@ failed: %@", keyChain, e); } @finally { } } return ret; } + (void)lhDelete:(NSString *)keyChain { NSMutableDictionary *keychainQuery = [self getKeychain:keyChain]; SecItemDelete((__bridge_retained CFDictionaryRef)keychainQuery); } @end
到这里是所有关键代码，放上下载地址：点击下载
最后，忘了件重要的事情，要在xcode中启用KeyChain：
当显示为ON的时候才能使用KeyChain。
