storing data locally on the iphone

Question

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.

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.

Would appreciate any advice on that.

Answer 1

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

1. Plist files
2. NSUserDefaults
3. UserDefault
4. File System
5. CoreData
6. SQLite DB

Answer 2

// 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]);
    }
}

Answer 3

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

Answer 4

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:

For example:

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"

Answer 5

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

[NSUserDefaults standardUserDefaults] 

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

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

Answer 6

You have basically two options to store data:

1. CoreData (if you are planning to use newer versions of iOS)
2. SQLite (supports any version of the 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).

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.

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