[置顶] IOS7开发～UDID解决方法

前言：IOS7中，UDID和MAC地址等设备唯一标识方法都被淘汰，但开发中，业务往往需要这个唯一标识，经过研究，还没找到可以完全替代UDID和MAC地址的方法，但退而求其次，找到了将UUID作为UDID使用的办法，UUID保证了序列号的唯一性，所以剩下问题就是解决如何保存UUID的问题了，经过调研，利用KeyChain可以保存数据，并且APP删除，重启机器情况下仍然不影响保存的数据，但如果用户刷系统，这种办法就不行了。下面奉上代码：

项目要引入：Security.framework

#import <UIKit/UIKit.h>
#import "KeychainHelper.h"

@interface ViewController : UIViewController

@end

#import "ViewController.h"

NSString * const KEY_DIC = @"com.company.app.dic";
NSString * const KEY_UDID = @"com.company.app.kUdidTest";

@interface ViewController ()

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];
}

- (NSString*) uuid
{
    CFUUIDRef puuid = CFUUIDCreate(nil);
    CFStringRef uuidString = CFUUIDCreateString(nil, puuid);
    NSString *result = (NSString *)CFStringCreateCopy(NULL, uuidString);
    CFRelease(puuid);
    CFRelease(uuidString);
    return [result autorelease];
}

- (void) touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    NSMutableDictionary *dic = (NSMutableDictionary *)[KeychainHelper load:KEY_DIC];
    NSString *udid = [dic objectForKey:KEY_UDID];
    
    if (udid)
    {
        NSLog(@"udid:%@", udid);
    }
    
    if (!udid)
    {
        NSLog(@"save");
        NSMutableDictionary *dic = [NSMutableDictionary dictionary];
        [dic setObject:[self uuid] forKey:KEY_UDID];
        
        [KeychainHelper save:KEY_DIC data:dic];
    }
}

@end

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#import <Foundation/Foundation.h>
#import <Security/Security.h>


@interface KeychainHelper : NSObject

+ (void) save:(NSString *)service data:(id)data;
+ (id)   load:(NSString *)service;
+ (void) deleteData:(NSString *)service;


@end

#import "KeychainHelper.h"

@implementation KeychainHelper

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


@end

这样就实现了即使删除App，当再次安装后还保存上次的数据不丢失。