iphone - 无法在 ios 中创建 sqlite3 数据库

Question

创建数据库代码

这段代码是正确的。我使用该代码创建了一个数据库，它成功运行并创建了一个数据库，但我测试了我的应用程序，所以我删除或删除了我的模拟器应用程序并再次运行我的应用程序，然后我看到没有创建数据库。

请告诉我我面临的实际问题是什么。

ClsUpdateNetworkViewController.h

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

@interface ClsUpdateNetworkViewController : UIViewController{

   UITextField *name;
   UITextField *phone;
   NSString *databasePath;
   sqlite3 *contactDB;
   int rowcount;

}

@property (nonatomic, strong) Person *person;
@property (nonatomic, strong) NSString *firstName;
@property (nonatomic, strong) NSString *lastName;
@property (nonatomic, strong) NSString *fullName;
@property (nonatomic, strong) NSString *phoneNumber;
@property (nonatomic, strong) NSString *workEmail;

@end

ClsUpdateNetworkViewController.m

 #import "ClsUpdateNetworkViewController.h"
 #import "ClsMainPageAppDelegate.h"
 #import "ClsAddressBookViewController.h"


@interface ClsUpdateNetworkViewController ()

@end

@implementation ClsUpdateNetworkViewController

@synthesize  person,firstName,lastName,fullName,phoneNumber,workEmail;
@synthesize name,phone;

- (void)viewDidLoad
{
   [super viewDidLoad];
// Do any additional setup after loading the view.

   [self createDatabase];
}



-(void) createDatabase
{
   NSString *docsDir;
   NSArray *dirPaths;

   // Get the documents directory
   dirPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

   docsDir = [dirPaths objectAtIndex:0];

   // Build the path to the database file
   databasePath = [[NSString alloc] initWithString: [docsDir stringByAppendingPathComponent: @"contacts.db"]];

   NSFileManager *filemgr = [NSFileManager defaultManager];

   if ([filemgr fileExistsAtPath: databasePath ] == NO)
   {
    const char *dbpath = [databasePath UTF8String];

       if (sqlite3_open(dbpath, &contactDB) == SQLITE_OK)
       {
           char *errMsg;
           const char *sql_stmt = "CREATE TABLE IF NOT EXISTS CONTACTS (ID INTEGER PRIMARY KEY AUTOINCREMENT, NAME TEXT, PHONE TEXT)";

           if (sqlite3_exec(contactDB, sql_stmt, NULL, NULL, &errMsg) != SQLITE_OK)
           {
               NSLog(@"Failed to create table");

           }

           sqlite3_close(contactDB);

       }
       else
       {
           NSLog(@"Failed to open/create database");

       }
   }

}

我测试或调试我的应用程序

Code is not going inside this condition.
if ([filemgr fileExistsAtPath: databasePath ] == NO)
{
    // inside code is not executed.
}

Answer 1

在 didFinishLaunchingWithOptions: 中调用此函数:

-(void)createdb
{
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *dbPath = [documentsDirectory stringByAppendingPathComponent:@"emp.sqlite"];

NSURL *dbURL = [NSURL fileURLWithPath:dbPath];

// copy a database from the bundle if not present
// on disk
NSFileManager *fm = [NSFileManager defaultManager];
if (![fm fileExistsAtPath:dbPath])
{
    NSURL *bundlePath = [[NSBundle mainBundle] URLForResource:@"emp" withExtension:@"sqlite"];
    NSError *error = nil;
    if (!bundlePath || ![fm copyItemAtURL:bundlePath toURL:dbURL error:&error]) {
        NSLog(@"error copying database from bundle: %@", error);
    }
}
else
{
    NSLog(@"Success in Copy file");
}
}