关于设备唯一标示UUID的问题与数据存储在KeyChain里边

UUID.h  代码如下：

#import <Foundation/Foundation.h>

@interface UUID : NSObject
+(NSString *)getUUID;
@end

UUID.m 代码如下：

#import "UUID.h"
#import "KeyChainStore.h"
#define KEY_USERNAME_PASSWORD @"com.company.app.usernamepassword"
@implementation UUID
+(NSString *)getUUID
{
NSString * strUUID = (NSString *)[KeyChainStore load:@"com.company.app.usernamepassword"];

//首次执行该方法时，uuid为空
if ([strUUID isEqualToString:@""] || !strUUID)
{
//生成一个uuid的方法
CFUUIDRef uuidRef = CFUUIDCreate(kCFAllocatorDefault);

strUUID = (NSString *)CFBridgingRelease(CFUUIDCreateString (kCFAllocatorDefault,uuidRef));

//将该uuid保存到keychain
[KeyChainStore save:KEY_USERNAME_PASSWORD data:strUUID];

}
return strUUID;
}
@end


KeyChainStore.h 代码如下 

#import <Foundation/Foundation.h>

@interface KeyChainStore : NSObject
+ (void)save:(NSString *)service data:(id)data;
+ (id)load:(NSString *)service;
+ (void)deleteKeyData:(NSString *)service;

@end

KeyChainStore.m 代码如下 

//
// KeyChainStore.m
// DaBangHui
//
// Created by DBH on 16/4/15.
// Copyright © 2016年张梦磊. All rights reserved.
//

#import "KeyChainStore.h"

@implementation KeyChainStore

+ (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:(__bridge NSData *)keyData];
} @catch (NSException *e) {
NSLog(@"Unarchive of %@ failed: %@", service, e);
} @finally {
}
}
if (keyData)
CFRelease(keyData);
return ret;
}

+ (void)deleteKeyData:(NSString *)service {
NSMutableDictionary *keychainQuery = [self getKeychainQuery:service];
SecItemDelete((CFDictionaryRef)keychainQuery);
}

@end

直接调用  

[UUID getUUID]