一、需求

多个小游戏app获取相同的设备唯一标识。

二、分析

iOS设备有很多设备标识,如:UDID、IDFA、IDFV、OpenIDFA、SimulateIDFA等。但是在iOS 7.0后很多标识就不能用了。多个app想要获取相同的设备唯一标识可以用到IDFV，然后再用KeyChain共享写入就能保证设备唯一标识相同了。

三、实现

3.1 确保多个app的BundleID前缀相同。

iOS6.x是通过BundleID前两部分来匹配，iOS7.x是通过除了最后一个部分来匹配。如果相同就是同一个Vender，共享同一个idfv的值。

3.2 多个app在同一开发者账号下

使用KeyChain来共享存储时，需要在相同的账号下，因为存储BundleID的时候默认在前面加上了账号的证书id。

3.3 在项目的 Build Phases中添加Security.framework库

3.4 在项目的 Signing & Capabilities中添加Keychain Sharing，加入Keychain Groups分组。每个app都设置相同的Keychain Groups值

3.5 导入文件 KeyChainTool.h/m 到项目中

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

@interface KeyChainTool : NSObject

+ (void)save:(NSString *)service data:(id)data;
+ (id)load:(NSString *)service;
+ (void)delete:(NSString *)service;
@end

//
//  customKeyChainTool.m
//

#import "KeyChainTool.h"
#import <Security/Security.h>

@implementation KeyChainTool
+ (NSMutableDictionary *)getKeychainQuery:(NSString *)service {
    //这个就和keychainitemwrapper里面提前预设了参数一样
    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)delete:(NSString *)service {
    NSMutableDictionary *keychainQuery = [self getKeychainQuery:service];
    SecItemDelete((CFDictionaryRef)keychainQuery);
}
@end

3.6 添加获取设备唯一标识的UUID方法

+ (NSString *)getUUID {
    
    NSString *strUUID = [(NSMutableDictionary*)[KeyChainTool load:@"com.guoke"] objectForKey:@"UUID"];
    if (!strUUID || strUUID.length == 0) {
        strUUID = [[[UIDevice currentDevice] identifierForVendor] UUIDString];
        NSMutableDictionary *usernamepasswordKVPairs = [NSMutableDictionary dictionary];
        [usernamepasswordKVPairs setObject:strUUID forKey:@"UUID"];
        [KeyChainTool save:@"com.guoke" data:usernamepasswordKVPairs];
    }

    return strUUID;
}

四、测试

同账号打二个app包
app1 ： com.guoke.test1
app2： com.guoke.test2