CIDCloudKeyManager

_README.md

iOS から iOS への端末移行時、iCloud を用いてセキュアにユーザを紐付けするコード

CIDCloudKeyManager.h

#import <Foundation/Foundation.h>

@interface CIDCloudKeyManager : NSObject

+ (instancetype)sharedManager;
- (void)startFetchingWithContainerIdentifier:(NSString *)identifier
                        storingCloudKeyBlock:(void(^)(NSString *cloudKeyID, NSString *cloudKeySecret))storingCloudKeyBlock
                         paringCloudKeyBlock:(void(^)(NSString *cloudKeyID, NSString *cloudKeySecret))paringCloudKeyBlock;

@end

CIDCloudKeyManager.m

#import "CIDCloudKeyManager.h"

@import CloudKit;

static NSString *const kCIDCloudKeyRecordID = @"TheCloudKey";
static NSString *const kCIDCloudKeyRecordType = @"CloudKey";
static NSString *const kCIDCloudKeySecretKey = @"secret";

static NSString *CIDMakeRandomKey(int length) {
    NSString *alphabet  = @"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXZY0123456789";
    NSMutableString *s = [NSMutableString stringWithCapacity:length];
    for (NSUInteger i = 0U; i < length; i++) {
        u_int32_t r = arc4random() % [alphabet length];
        unichar c = [alphabet characterAtIndex:r];
        [s appendFormat:@"%C", c];
    }
    return s.copy;
};

static void CIDSaveCloudKey(NSString *cloudKeyID, NSString *secret) {
    NSLog(@"Saving cloud key: %@:%@", cloudKeyID, secret);
}

static void CIDPairCloudKey(NSString *cloudKeyID, NSString *secret) {
    NSLog(@"Checking cloud key: %@:%@", cloudKeyID, secret);
}

static CKRecordID *CIDMakeTheCloudKeyRecordID() {
    return [[CKRecordID alloc] initWithRecordName:kCIDCloudKeyRecordID];
}

static CKRecord *CIDMakeCloudKeyWithRandomSecret() {
    NSString *secret = CIDMakeRandomKey(32);
    
    CKRecord *cloudKey = [[CKRecord alloc] initWithRecordType:kCIDCloudKeyRecordType recordID:CIDMakeTheCloudKeyRecordID()];
    [cloudKey setObject:secret forKey:kCIDCloudKeySecretKey];
    
    return cloudKey;
}

@implementation CIDCloudKeyManager

+ (instancetype)sharedManager {
    static CIDCloudKeyManager *_instance;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        _instance = [[CIDCloudKeyManager alloc] init];
    });
    return _instance;
}

- (void)startFetchingWithContainerIdentifier:(NSString *)identifier storingCloudKeyBlock:(void (^)(NSString *, NSString *))storingCloudKeyBlock paringCloudKeyBlock:(void (^)(NSString *, NSString *))paringCloudKeyBlock {
    CKContainer *container = [CKContainer defaultContainer];
    if (identifier != nil) {
        container = [CKContainer containerWithIdentifier:identifier];
    }
    
    [container fetchUserRecordIDWithCompletionHandler:^(CKRecordID *recordID, NSError *error) {
        if (recordID == nil || error != nil) {
            NSLog(@"%@", error);
            return;
        }
        
        NSString *userId = recordID.recordName;
        
        NSLog(@"Found record ID! Try to fetch CloudKey.");
        
        CKDatabase *db = container.privateCloudDatabase;
        
        [db fetchRecordWithID:CIDMakeTheCloudKeyRecordID() completionHandler:^(CKRecord *record, NSError *error) {
            if (record != nil) {
                NSLog(@"Found!! Should do paring.");
                NSString *secret = [record objectForKey:kCIDCloudKeySecretKey];
                if (paringCloudKeyBlock != nil) {
                    paringCloudKeyBlock(userId, secret);
                }
                return;
            }
            
            if ([error.domain isEqualToString:CKErrorDomain] && error.code == CKErrorUnknownItem) {
                NSLog(@"Cloud not find CloudKey. Try to create CloudKey.");
                CKRecord *cloudKey = CIDMakeCloudKeyWithRandomSecret();
                
                [db saveRecord:cloudKey completionHandler:^(CKRecord *record, NSError *error) {
                    if (error != nil) {
                        NSLog(@"Error occured during saving: %@", error);
                    }
                    
                    NSLog(@"Complete everything!");
                    NSString *secret = [record objectForKey:kCIDCloudKeySecretKey];
                    CIDSaveCloudKey(userId, secret);
                    if (storingCloudKeyBlock != nil) {
                        storingCloudKeyBlock(userId, secret);
                    }
                }];
            } else {
                NSLog(@"Unknown error occured. Should retry?");
            }
        }];
    }];
}

@end