在iphone上本地存储数据

I am building an app where I'd like to store user information locally on the device, without using any server database - but everything on the device side. I am looking to store specific user locations and show it in a table view, and so even when the user launches the app later - I can pull the history and feed the history table with the past locations. Basically a read/write capability from a local database.

我正在开发一个应用程序，我想在设备上本地存储用户信息，而不需要使用任何服务器数据库——而是设备端上的所有内容。我希望存储特定的用户位置，并在表视图中显示它，因此，即使用户稍后启动应用程序，我也可以提取历史记录并将历史表与过去的位置关联起来。从本地数据库中读取/写入功能。

Now, I know that there were many questions like that before but I could not find one that addresses saving data locally without an external data base. I am not sure, for example, that using Core Data is the correct and simplest thing to do here.

现在，我知道以前有很多这样的问题，但是我找不到一个没有外部数据库就能在本地保存数据的问题。例如，我不确定在这里使用核心数据是正确和最简单的事情。

Would appreciate any advice on that.

如有任何建议将不胜感激。

7 个解决方案

#1

For simple data you should use NSUserDefaults. CoreData is very cool but mainly to store DB structures, and introduces complexity (but i love it:)). If you just need to store String, Array and so on (basically prefs), you can go with NSUserDefaults:

对于简单的数据，应该使用NSUserDefaults。CoreData非常酷，但主要用于存储DB结构，并引入了复杂性(但我喜欢:)。如果你只需要存储字符串、数组等(基本上是prefs)，你可以使用NSUserDefaults:

For example:

例如:

NSUserDefaults *prefs = [NSUserDefaults standardUserDefaults];  //load NSUserDefaults
NSArray *fakeFavs = [[ NSArray alloc] initWithObjects:@"2",@"4", @"100", nil];  //declare array to be stored in NSUserDefaults
[prefs setObject:fakeFavs forKey:@"favourites"];  //set the prev Array for key value "favourites"

#2

You have basically two options to store data:

你基本上有两个存储数据的选项:

1. CoreData (if you are planning to use newer versions of iOS)
2. CoreData(如果您打算使用更新的iOS版本)
3. SQLite (supports any version of the SDK)
4. SQLite(支持任何版本的SDK)

CoreData uses SQLite, its API is a little bit easier to use (you don't need to know SQL or write a lot of functions to read and write your data).

CoreData使用SQLite，它的API更易于使用(您不需要了解SQL或编写大量函数来读取和写入数据)。

SQLite API is still a great choice, since it uses the C API for SQLite, which is very well documented and straightforward to use. It has the benefit that you can target older iOS platforms with this.

SQLite API仍然是一个很好的选择，因为它使用的是SQLite的C API，它的文档很好，使用起来也很简单。它的好处是，你可以用它来定位较老的iOS平台。

With both options, data will be stored client side, and will be backed every time user syncs his/her phone with iTunes.

有了这两个选项，数据将被存储在客户端，并且每次用户将他/她的手机与iTunes同步时，数据将被备份。

#3

if you just storing a few values and don't need any search logic, you could take a look into NSUserDefaults

如果只存储一些值，不需要任何搜索逻辑，那么可以查看NSUserDefaults

[NSUserDefaults standardUserDefaults] 

its just an dictionary where you can store arrays, strings, int, objects and access by a NSString key

它只是一个字典，你可以存储数组、字符串、int、对象和通过NSString键访问

internally it's a just plist, so you can open it with xcode to quicky see the current state

在内部它只是一个plist，所以您可以使用xcode打开它以快速查看当前状态

#4

You have a few different ways to store application data on your iPhone.

在iPhone上存储应用程序数据有几种不同的方法。

1. Plist files
2. Plist文件
3. NSUserDefaults
4. NSUserDefaults
5. UserDefault
6. UserDefault
7. File System
8. 文件系统
9. CoreData
10. CoreData
11. SQLite DB
12. SQLite数据库

#5

I recommend using Realm for more generalized solutions.

我建议使用Realm来获得更广义的解。

#6

Select Query::::::

NSArray  *array_hiback =[app.sk lookupAllForSQL:@"SELECT * FROM cycle_datagathering_begoodyourselef ORDER BY RANDOM() LIMIT 1"];
    NSLog(@"%@",array_hiback);      

insert Query:::::

 NSMutableDictionary *dict=[[NSMutableDictionary alloc]init];
[dict setObject:@"0" forKey:@"isuploaded"];
        [app.sk insertDictionary:dict forTable:@"mindeditor"];
        [dict release];


update Query::::


  NSMutableDictionary *updatedata=[[NSMutableDictionary alloc]init];
[updatedata setObject:  [[NSUserDefaults standardUserDefaults] objectForKey:@"savecycleid"] forKey:@"cycleid"];


delete Query:::::

        [app.sk deleteWhere:[NSString stringWithFormat:@"rowid=%@",str] forTable:@"mindeditor"];

            [app.sk updateDictionary:updatedata forTable:@"mindeditor" where:[NSString stringWithFormat:@"rowid=%@", [[checkarray objectAtIndex:checkarray.count-1] objectForKey:@"cycleid"]]];
            [updatedata release];

  - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
        {


            sk = [[SKDatabase alloc] init];
            NSString *db = @"MindEditor.db";
            [sk initWithDynamicFile:db];
            userid=@"0";
        }


       SKDatabase.h


    //
    //  SKDatabase.h
    //  Version 1.1
    //
    //  Created by Shannon Appelcline on 9/11/08.
    //  Copyright 2008 __MyCompanyName__. All rights reserved.
    //

    #import <UIKit/UIKit.h>
    #import <sqlite3.h>

    @protocol SKDatabaseDelegate <NSObject>
    @optional
    - (void)databaseTableWasUpdated:(NSString *)table;
    @end

    @interface SKDatabase : NSObject {

        id<SKDatabaseDelegate> delegate;
        sqlite3 *dbh;
        BOOL dynamic;
    }

    @property (assign) id<SKDatabaseDelegate> delegate;
    @property sqlite3 *dbh;
    @property BOOL dynamic;

    - (id)initWithFile:(NSString *)dbFile;
    - (id)initWithDynamicFile:(NSString *)dbFile;
    - (void)close;

    - (sqlite3_stmt *)prepare:(NSString *)sql;

    - (id)lookupColForSQL:(NSString *)sql;
    - (NSDictionary *)lookupRowForSQL:(NSString *)sql;
    - (NSArray *)lookupAllForSQL:(NSString *)sql;

    - (int)lookupCountWhere:(NSString *)where forTable:(NSString *)table;
    - (int)lookupMax:(NSString *)key Where:(NSString *)where forTable:(NSString *)table;
    - (int)lookupSum:(NSString *)key Where:(NSString *)where forTable:(NSString *)table;

    - (void)insertArray:(NSArray *)dbData forTable:(NSString *)table;
    - (void)insertDictionary:(NSDictionary *)dbData forTable:(NSString *)table;

    - (void)updateArray:(NSArray *)dbData forTable:(NSString *)table;
    - (void)updateArray:(NSArray *)dbData forTable:(NSString *)table where:(NSString *)where;
    - (void)updateDictionary:(NSDictionary *)dbData forTable:(NSString *)table;
    - (void)updateDictionary:(NSDictionary *)dbData forTable:(NSString *)table where:(NSString *)where;
    - (void)updateSQL:(NSString *)sql forTable:(NSString *)table;

    - (void)deleteWhere:(NSString *)where forTable:(NSString *)table;

    - (BOOL)runDynamicSQL:(NSString *)sql forTable:(NSString *)table;

    @end

       SKDatabase.m




    //
    //  SKDatabase.m
    //  Version 1.1
    //
    //  Created by Shannon Appelcline on 9/11/08.
    //  Copyright 2008 __MyCompanyName__. All rights reserved.
    //

    #import "SKDatabase.h"

    @implementation SKDatabase

    @synthesize delegate;
    @synthesize dbh;
    @synthesize dynamic;

    // Two ways to init: one if you're just SELECTing from a database, one if you're UPDATing
    // and or INSERTing

    - (id)initWithFile:(NSString *)dbFile {
        if (self = [super init]) {

            NSString *paths = [[NSBundle mainBundle] resourcePath];
            NSString *path = [paths stringByAppendingPathComponent:dbFile];

            int result = sqlite3_open([path UTF8String], &dbh);
            NSAssert1(SQLITE_OK == result, NSLocalizedStringFromTable(@"Unable to open the sqlite database (%@).", @"Database", @""), [NSString stringWithUTF8String:sqlite3_errmsg(dbh)]); 
            self.dynamic = NO;
        }

        return self;    
    }

    - (id)initWithDynamicFile:(NSString *)dbFile {
        if (self = [super init]) {

            NSArray *docPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
            NSString *docDir = [docPaths objectAtIndex:0];
            NSString *docPath = [docDir stringByAppendingPathComponent:dbFile];

            NSFileManager *fileManager = [NSFileManager defaultManager];

            if (![fileManager fileExistsAtPath:docPath]) {

                NSString *origPaths = [[NSBundle mainBundle] resourcePath];
                NSString *origPath = [origPaths stringByAppendingPathComponent:dbFile];

                NSError *error;
                int success = [fileManager copyItemAtPath:origPath toPath:docPath error:&error];            
                NSAssert1(success,[NSString stringWithString:@"Failed to copy database into dynamic location"],error);
            }
            int result = sqlite3_open([docPath UTF8String], &dbh);
            NSAssert1(SQLITE_OK == result, NSLocalizedStringFromTable(@"Unable to open the sqlite database (%@).", @"Database", @""), [NSString stringWithUTF8String:sqlite3_errmsg(dbh)]); 
            self.dynamic = YES;
        }

        return self;    
    }

    // Users should never need to call prepare

    - (sqlite3_stmt *)prepare:(NSString *)sql {

        const char *utfsql = [sql UTF8String];

        sqlite3_stmt *statement;

        if (sqlite3_prepare([self dbh],utfsql,-1,&statement,NULL) == SQLITE_OK) {
            return statement;
        } else {
            return 0;
        }
    }

    // Three ways to lookup results: for a variable number of responses, for a full row
    // of responses, or for a singular bit of data

    - (NSArray *)lookupAllForSQL:(NSString *)sql {
        sqlite3_stmt *statement;
        id result;
        NSMutableArray *thisArray = [NSMutableArray arrayWithCapacity:4];
        if (statement = [self prepare:sql]) {
            while (sqlite3_step(statement) == SQLITE_ROW) { 
                NSMutableDictionary *thisDict = [NSMutableDictionary dictionaryWithCapacity:4];
                for (int i = 0 ; i < sqlite3_column_count(statement) ; i++) 
                {
                    if (sqlite3_column_decltype(statement,i) != NULL &&
                        strcasecmp(sqlite3_column_decltype(statement,i),"Boolean") == 0)
                    {
                        result = [NSNumber numberWithBool:(BOOL)sqlite3_column_int(statement,i)];
                    } 
                    else if (sqlite3_column_type(statement, i) == SQLITE_TEXT)
                    {
                        result = [NSString stringWithUTF8String:(char *)sqlite3_column_text(statement,i)];
                    } 
                    else if 
                        (sqlite3_column_type(statement,i) == SQLITE_INTEGER)
                    {
                        result = [NSNumber numberWithInt:(int)sqlite3_column_int(statement,i)];
                    } 
                    else if (sqlite3_column_type(statement,i) == SQLITE_FLOAT)
                    {
                        result = [NSNumber numberWithFloat:(float)sqlite3_column_double(statement,i)];                  
                    }
                    else 
                    {
                        result = [NSString stringWithUTF8String:(char *)sqlite3_column_text(statement,i)];
                    }
                    if (result) 
                    {
                        [thisDict setObject:result
                                     forKey:[NSString stringWithUTF8String:sqlite3_column_name(statement,i)]];
                    }
                }
                [thisArray addObject:[NSDictionary dictionaryWithDictionary:thisDict]];
                [thisArray retain];
            }
        }
        sqlite3_finalize(statement);
        return thisArray;
    }

    - (NSDictionary *)lookupRowForSQL:(NSString *)sql {
        sqlite3_stmt *statement;
        id result;
        NSMutableDictionary *thisDict = [NSMutableDictionary dictionaryWithCapacity:4];
        if (statement = [self prepare:sql]) 
        {
            if (sqlite3_step(statement) == SQLITE_ROW) 
            {   
                for (int i = 0 ; i < sqlite3_column_count(statement) ; i++) 
                {
                    if (strcasecmp(sqlite3_column_decltype(statement,i),"Boolean") == 0)
                    {
                        result = [NSNumber numberWithBool:(BOOL)sqlite3_column_int(statement,i)];
                    } 
                    else if (sqlite3_column_type(statement, i) == SQLITE_TEXT) 
                    {
                        result = [NSString stringWithUTF8String:(char *)sqlite3_column_text(statement,i)];
                    } 
                    else if (sqlite3_column_type(statement,i) == SQLITE_INTEGER)
                    {
                        result = [NSNumber numberWithInt:(int)sqlite3_column_int(statement,i)];
                    } 
                    else if (sqlite3_column_type(statement,i) == SQLITE_FLOAT)
                    {
                        result = [NSNumber numberWithFloat:(float)sqlite3_column_double(statement,i)];                  
                    } 
                    else 
                    {
                        result = [NSString stringWithUTF8String:(char *)sqlite3_column_text(statement,i)];
                    }
                    if (result) 
                    {
                        [thisDict setObject:result
                                     forKey:[NSString stringWithUTF8String:sqlite3_column_name(statement,i)]];
                    }
                }
            }
        }
        sqlite3_finalize(statement);
        return thisDict;
    }

    - (id)lookupColForSQL:(NSString *)sql {

        sqlite3_stmt *statement;
        id result;
        if (statement = [self prepare:sql]) {
            if (sqlite3_step(statement) == SQLITE_ROW) {        
                if (strcasecmp(sqlite3_column_decltype(statement,0),"Boolean") == 0) {
                    result = [NSNumber numberWithBool:(BOOL)sqlite3_column_int(statement,0)];
                } else if (sqlite3_column_type(statement, 0) == SQLITE_TEXT) {
                    result = [NSString stringWithUTF8String:(char *)sqlite3_column_text(statement,0)];
                } else if (sqlite3_column_type(statement,0) == SQLITE_INTEGER) {
                    result = [NSNumber numberWithInt:(int)sqlite3_column_int(statement,0)];
                } else if (sqlite3_column_type(statement,0) == SQLITE_FLOAT) {
                    result = [NSNumber numberWithDouble:(double)sqlite3_column_double(statement,0)];                    
                } else {
                    result = [NSString stringWithUTF8String:(char *)sqlite3_column_text(statement,0)];
                }
            }
        }
        sqlite3_finalize(statement);
        return result;

    }

    // Simple use of COUNTS, MAX, etc.

    - (int)lookupCountWhere:(NSString *)where forTable:(NSString *)table {

        int tableCount = 0;
        NSString *sql = [NSString stringWithFormat:@"SELECT COUNT(*) FROM %@ WHERE %@",
                         table,where];      
        sqlite3_stmt *statement;

        if (statement = [self prepare:sql]) {
            if (sqlite3_step(statement) == SQLITE_ROW) {        
                tableCount = sqlite3_column_int(statement,0);
            }
        }
        sqlite3_finalize(statement);
        return tableCount;

    }

    - (int)lookupMax:(NSString *)key Where:(NSString *)where forTable:(NSString *)table {

        int tableMax = 0;
        NSString *sql = [NSString stringWithFormat:@"SELECT MAX(%@) FROM %@ WHERE %@",
                         key,table,where];      
        sqlite3_stmt *statement;
        if (statement = [self prepare:sql]) {
            if (sqlite3_step(statement) == SQLITE_ROW) {        
                tableMax = sqlite3_column_int(statement,0);
            }
        }
        sqlite3_finalize(statement);
        return tableMax;

    }

    - (int)lookupSum:(NSString *)key Where:(NSString *)where forTable:(NSString *)table {

        int tableSum = 0;
        NSString *sql = [NSString stringWithFormat:@"SELECT SUM(%@) FROM %@ WHERE %@",
                         key,table,where];      
        sqlite3_stmt *statement;
        if (statement = [self prepare:sql]) {
            if (sqlite3_step(statement) == SQLITE_ROW) {        
                tableSum = sqlite3_column_int(statement,0);
            }
        }
        sqlite3_finalize(statement);
        return tableSum;

    }

    // INSERTing and UPDATing

    - (void)insertArray:(NSArray *)dbData forTable:(NSString *)table {

    //  NSMutableString *sql = [NSMutableString stringWithCapacity:16];
    //  [sql appendFormat:@"INSERT INTO %@ (",table];
    //  
    //  
    //  for (int i = 0 ; i < [dbData count] ; i++) {
    //      NSLog(@"%@",[[dbData objectAtIndex:i] objectForKey:@"mid"]);
    //      [sql appendFormat:@"%@",[[dbData objectAtIndex:i] objectForKey:@"key"]];
    //      if (i + 1 < [dbData count]) {
    //          [sql appendFormat:@", "];
    //      }
    //  }
    //  [sql appendFormat:@") VALUES("];
    //  for (int i = 0 ; i < [dbData count] ; i++) {
    //      if ([[[dbData objectAtIndex:i] objectForKey:@"value"] intValue]) {
    //          [sql appendFormat:@"%@",[[[dbData objectAtIndex:i] objectForKey:@"value"] intValue]];
    //      } else {
    //          [sql appendFormat:@"'%@'",[[dbData objectAtIndex:i] objectForKey:@"value"]];
    //      }
    //      if (i + 1 < [dbData count]) {
    //          [sql appendFormat:@", "];
    //      }
    //  }
    //  [sql appendFormat:@")"];
    //  [self runDynamicSQL:sql forTable:table];
        for(int i=0;i<[dbData count];i++)
        {
            NSDictionary *dict=[dbData objectAtIndex:i];
            NSMutableString *sql = [NSMutableString stringWithCapacity:16];
            [sql appendFormat:@"INSERT INTO %@ (",table];

            NSArray *dataKeys = [dict allKeys];
            for (int i = 0 ; i < [dataKeys count] ; i++) {
                [sql appendFormat:@"%@",[dataKeys objectAtIndex:i]];
                if (i + 1 < [dataKeys count]) {
                    [sql appendFormat:@", "];
                }
            }

            [sql appendFormat:@") VALUES("];
            for (int i = 0 ; i < [dataKeys count] ; i++) {
                if ([[dict objectForKey:[dataKeys objectAtIndex:i]] intValue]) {
                    [sql appendFormat:@"%@",[dict objectForKey:[dataKeys objectAtIndex:i]]];
                } else {
                    [sql appendFormat:@"'%@'",[dict objectForKey:[dataKeys objectAtIndex:i]]];
                }
                if (i + 1 < [dict count]) {
                    [sql appendFormat:@", "];
                }
            }

            [sql appendFormat:@")"];
            [self runDynamicSQL:sql forTable:table];
        }
    }

    - (void)insertDictionary:(NSDictionary *)dbData forTable:(NSString *)table {

        NSMutableString *sql = [NSMutableString stringWithCapacity:16];
        [sql appendFormat:@"INSERT INTO %@ (",table];

        NSArray *dataKeys = [dbData allKeys];
        for (int i = 0 ; i < [dataKeys count] ; i++) {
            [sql appendFormat:@"%@",[dataKeys objectAtIndex:i]];
            if (i + 1 < [dbData count]) {
                [sql appendFormat:@", "];
            }
        }

        [sql appendFormat:@") VALUES("];
        for (int i = 0 ; i < [dataKeys count] ; i++) {
            //if ([[dbData objectForKey:[dataKeys objectAtIndex:i]] intValue]) {
    //          [sql appendFormat:@"%@",[dbData objectForKey:[dataKeys objectAtIndex:i]]];
    //      } else {

            [sql appendFormat:@"'%@'",[dbData objectForKey:[dataKeys objectAtIndex:i]]];
            //}
            if (i + 1 < [dbData count]) {
                [sql appendFormat:@", "];
            }
        }

        [sql appendFormat:@")"];
        [self runDynamicSQL:sql forTable:table];
    }

    - (void)updateArray:(NSArray *)dbData forTable:(NSString *)table { 
        [self updateArray:dbData forTable:table where:NULL];
    }

    - (void)updateArray:(NSArray *)dbData forTable:(NSString *)table where:(NSString *)where {

        NSMutableString *sql = [NSMutableString stringWithCapacity:16];
        [sql appendFormat:@"UPDATE %@ SET ",table];

        for (int i = 0 ; i < [dbData count] ; i++) {
            if ([[[dbData objectAtIndex:i] objectForKey:@"value"] intValue]) {
                [sql appendFormat:@"%@=%@",
                 [[dbData objectAtIndex:i] objectForKey:@"key"],
                 [[dbData objectAtIndex:i] objectForKey:@"value"]];
            } else {
                [sql appendFormat:@"%@='%@'",
                 [[dbData objectAtIndex:i] objectForKey:@"key"],
                 [[dbData objectAtIndex:i] objectForKey:@"value"]];
            }       
            if (i + 1 < [dbData count]) {
                [sql appendFormat:@", "];
            }
        }
        if (where != NULL) {
            [sql appendFormat:@" WHERE %@",where];
        } else {
            [sql appendFormat:@" WHERE 1",where];
        }       
        [self runDynamicSQL:sql forTable:table];
    }

    - (void)updateDictionary:(NSDictionary *)dbData forTable:(NSString *)table { 
        [self updateDictionary:dbData forTable:table where:NULL];
    }

    - (void)updateDictionary:(NSDictionary *)dbData forTable:(NSString *)table where:(NSString *)where {

        NSMutableString *sql = [NSMutableString stringWithCapacity:16];
        [sql appendFormat:@"UPDATE %@ SET ",table];

        NSArray *dataKeys = [dbData allKeys];
        for (int i = 0 ; i < [dataKeys count] ; i++) {
            if ([[dbData objectForKey:[dataKeys objectAtIndex:i]] intValue]) {
                [sql appendFormat:@"%@=%@",
                 [dataKeys objectAtIndex:i],
                 [dbData objectForKey:[dataKeys objectAtIndex:i]]];
            } else {
                [sql appendFormat:@"%@='%@'",
                 [dataKeys objectAtIndex:i],
                 [dbData objectForKey:[dataKeys objectAtIndex:i]]];
            }       
            if (i + 1 < [dbData count]) {
                [sql appendFormat:@", "];
            }
        }
        if (where != NULL) {
            [sql appendFormat:@" WHERE %@",where];
        }
        [self runDynamicSQL:sql forTable:table];
    }

    - (void)updateSQL:(NSString *)sql forTable:(NSString *)table {
        [self runDynamicSQL:sql forTable:table];
    }

    - (void)deleteWhere:(NSString *)where forTable:(NSString *)table {

        NSString *sql = [NSString stringWithFormat:@"DELETE FROM %@ WHERE %@",
                         table,where];
        [self runDynamicSQL:sql forTable:table];
    }

    // INSERT/UPDATE/DELETE Subroutines

    - (BOOL)runDynamicSQL:(NSString *)sql forTable:(NSString *)table {

        int result;
        //NSAssert1(self.dynamic == 1,[NSString stringWithString:@"Tried to use a dynamic function on a static database"],NULL);
        sqlite3_stmt *statement;
        if (statement = [self prepare:sql]) {
            result = sqlite3_step(statement);
        }       
        sqlite3_finalize(statement);
        if (result) {
            if (self.delegate != NULL && [self.delegate respondsToSelector:@selector(databaseTableWasUpdated:)]) {
                [delegate databaseTableWasUpdated:table];
            }   
            return YES;
        } else {
            return NO;
        }

    }

    // requirements for closing things down

    - (void)dealloc {
        [self close];
        [delegate release];
        [super dealloc];
    }

    - (void)close {

        if (dbh) {
            sqlite3_close(dbh);
        }
    }

    @end

#7

// Create Database file

- (void)createEditableCopyOfDatabaseIfNeeded
{
    // First, test for existence.
    BOOL success;
    NSFileManager *fileManager = [NSFileManager defaultManager];
    NSError *error;
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSLog(@"%@",documentsDirectory);
    NSString *writableDBPath = [documentsDirectory stringByAppendingPathComponent:@"TestDB.sqlite"];
    success = [fileManager fileExistsAtPath:writableDBPath];
    if (success) return;

    // The writable database does not exist, so copy the default to the appropriate location.

    NSString *defaultDBPath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"TestDB.sqlite"];
    success = [fileManager copyItemAtPath:defaultDBPath toPath:writableDBPath error:&error];
    if (!success) {
        NSAssert1(0, @"Failed to create writable database file with message '%@'.", [error localizedDescription]);
    }
}