Use persistent UID for iOS

RNDeviceInfo/DeviceUID.h

+#import <Foundation/Foundation.h>
+
+@interface DeviceUID : NSObject
++ (NSString *)uid;
+@end

RNDeviceInfo/DeviceUID.m

+// Initial work from:
+// https://gist.github.com/miguelcma/e8f291e54b025815ca46
+// Modified as the original version crashes.
+
+#import "DeviceUID.h"
+
+@import UIKit;
+
+@interface DeviceUID ()
+
+@property(nonatomic, strong, readonly) NSString *uidKey;
+@property(nonatomic, strong, readonly) NSString *uid;
+
+@end
+
+@implementation DeviceUID
+
+@synthesize uid = _uid;
+
+#pragma mark - Public methods
+
++ (NSString *)uid {
+    return [[[DeviceUID alloc] initWithKey:@"deviceUID"] uid];
+}
+
+#pragma mark - Instance methods
+
+- (id)initWithKey:(NSString *)key {
+    self = [super init];
+    if (self) {
+        _uidKey = key;
+        _uid = nil;
+    }
+    return self;
+}
+
+/*! Returns the Device UID.
+    The UID is obtained in a chain of fallbacks:
+      - Keychain
+      - NSUserDefaults
+      - Apple IFV (Identifier for Vendor)
+      - Generate a random UUID if everything else is unavailable
+    At last, the UID is persisted if needed to.
+ */
+- (NSString *)uid {
+    if (!_uid) _uid = [[self class] valueForKeychainKey:_uidKey service:_uidKey];
+    if (!_uid) _uid = [[self class] valueForUserDefaultsKey:_uidKey];
+    if (!_uid) _uid = [[self class] appleIFA];
+    if (!_uid) _uid = [[self class] appleIFV];
+    if (!_uid) _uid = [[self class] randomUUID];
+    [self save];
+    return _uid;
+}
+
+/*! Persist UID to NSUserDefaults and Keychain, if not yet saved
+ */
+- (void)save {
+  if (![DeviceUID valueForUserDefaultsKey:_uidKey]) {
+    [DeviceUID setValue:_uid forUserDefaultsKey:_uidKey];
+  }
+  if (![DeviceUID valueForKeychainKey:_uidKey service:_uidKey]) {
+    [DeviceUID setValue:_uid forKeychainKey:_uidKey inService:_uidKey];
+  }
+}
+
+#pragma mark - Keychain methods
+
+/*! Create as generic NSDictionary to be used to query and update Keychain items.
+ *  param1
+ *  param2
+ */
++ (NSMutableDictionary *)keychainItemForKey:(NSString *)key service:(NSString *)service {
+    NSMutableDictionary *keychainItem = [[NSMutableDictionary alloc] init];
+    keychainItem[(__bridge id)kSecClass] = (__bridge id)kSecClassGenericPassword;
+    keychainItem[(__bridge id)kSecAttrAccessible] = (__bridge id)kSecAttrAccessibleAlways;
+    keychainItem[(__bridge id)kSecAttrAccount] = key;
+    keychainItem[(__bridge id)kSecAttrService] = service;
+    return keychainItem;
+}
+
+/*! Sets
+ *  param1
+ *  param2
+ */
++ (OSStatus)setValue:(NSString *)value forKeychainKey:(NSString *)key inService:(NSString *)service {
+    NSMutableDictionary *keychainItem = [[self class] keychainItemForKey:key service:service];
+    keychainItem[(__bridge id)kSecValueData] = [value dataUsingEncoding:NSUTF8StringEncoding];
+    return SecItemAdd((__bridge CFDictionaryRef)keychainItem, NULL);
+}
+
++ (NSString *)valueForKeychainKey:(NSString *)key service:(NSString *)service {
+    OSStatus status;
+    NSMutableDictionary *keychainItem = [[self class] keychainItemForKey:key service:service];
+    keychainItem[(__bridge id)kSecReturnData] = (__bridge id)kCFBooleanTrue;
+    keychainItem[(__bridge id)kSecReturnAttributes] = (__bridge id)kCFBooleanTrue;
+    CFDictionaryRef result = nil;
+    status = SecItemCopyMatching((__bridge CFDictionaryRef)keychainItem, (CFTypeRef *)&result);
+    if (status != noErr) {
+        return nil;
+    }
+    NSDictionary *resultDict = (__bridge_transfer NSDictionary *)result;
+    NSData *data = resultDict[(__bridge id)kSecValueData];
+    if (!data) {
+        return nil;
+    }
+    return [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
+}
+
+#pragma mark - NSUserDefaults methods
+
++ (BOOL)setValue:(NSString *)value forUserDefaultsKey:(NSString *)key {
+    [[NSUserDefaults standardUserDefaults] setObject:value forKey:key];
+    return [[NSUserDefaults standardUserDefaults] synchronize];
+}
+
++ (NSString *)valueForUserDefaultsKey:(NSString *)key {
+    return [[NSUserDefaults standardUserDefaults] objectForKey:key];
+}
+
+#pragma mark - UID Generation methods
+
++ (NSString *)appleIFA {
+    NSString *ifa = nil;
+    Class ASIdentifierManagerClass = NSClassFromString(@"ASIdentifierManager");
+    if (ASIdentifierManagerClass) { // a dynamic way of checking if AdSupport.framework is available
+        SEL sharedManagerSelector = NSSelectorFromString(@"sharedManager");
+        id sharedManager = ((id (*)(id, SEL))[ASIdentifierManagerClass methodForSelector:sharedManagerSelector])(ASIdentifierManagerClass, sharedManagerSelector);
+        SEL advertisingIdentifierSelector = NSSelectorFromString(@"advertisingIdentifier");
+        NSUUID *advertisingIdentifier = ((NSUUID* (*)(id, SEL))[sharedManager methodForSelector:advertisingIdentifierSelector])(sharedManager, advertisingIdentifierSelector);
+        ifa = [advertisingIdentifier UUIDString];
+    }
+    return ifa;
+}
+
++ (NSString *)appleIFV {
+    if(NSClassFromString(@"UIDevice") && [UIDevice instancesRespondToSelector:@selector(identifierForVendor)]) {
+        // only available in iOS >= 6.0
+        return [[UIDevice currentDevice].identifierForVendor UUIDString];
+    }
+    return nil;
+}
+
++ (NSString *)randomUUID {
+    if(NSClassFromString(@"NSUUID")) {
+        return [[NSUUID UUID] UUIDString];
+    }
+    CFUUIDRef uuidRef = CFUUIDCreate(kCFAllocatorDefault);
+    CFStringRef cfuuid = CFUUIDCreateString(kCFAllocatorDefault, uuidRef);
+    CFRelease(uuidRef);
+    NSString *uuid = [((__bridge NSString *) cfuuid) copy];
+    CFRelease(cfuuid);
+    return uuid;
+}
+
+@end

RNDeviceInfo/RNDeviceInfo.m

@@ -7,6 +7,7 @@
 //
 
 #import "RNDeviceInfo.h"
+#import "DeviceUID.h"
 
 @interface RNDeviceInfo()
 
@@ -146,7 +147,7 @@ RCT_EXPORT_MODULE()
     UIDevice *currentDevice = [UIDevice currentDevice];
 
     NSUUID *identifierForVendor = [currentDevice identifierForVendor];
-    NSString *uniqueId = [identifierForVendor UUIDString];
+    NSString *uniqueId = [DeviceUID uid];
 
     return @{
              @"systemName": currentDevice.systemName,