[NSBundle mainBundle] pathForResource返回nil

Question

I'm trying to connect my app to SQLite database but I get messages that tell me that the database is created but there are no tables.

I debugged the program and discovered that [[NSBundle mainBundle] pathForResource] always returns nil

NSString* file = [[NSBundle mainBundle]pathForResource:_databaseName ofType:_databaseType];

Why is this happening? Please help me!

Answer 1

First : make sure your database is in the app bundle.

Then you need to implement methods to copy the path to the documentary Directory .as these

-(NSString *) getDBPath:(NSString*)databaseName {
// search for the existed paths
NSArray *paths = NSSearchPathForDirectoriesInDomains(  NSDocumentDirectory , NSUserDomainMask, YES);
  NSString *documentsDir = [paths objectAtIndex:0];


return [documentsDir stringByAppendingPathComponent:databaseName];

}

- (void) InstantiateYourDatabase:(NSString *)DatabaseName {


//Using NSFileManager we can perform many file system operations.

NSFileManager *fileManager = [NSFileManager defaultManager];

NSError *error;
NSString *dpname=DatabaseName;

_dbPath = [self getDBPath:dpname];

BOOL success = [fileManager fileExistsAtPath:_dbPath];

NSLog(@"success == %i",success);

if( !success) {

    NSString *defaultDBPath = [[[NSBundle mainBundle] resourcePath] 
                               stringByAppendingPathComponent:DatabaseName];
    success = [fileManager copyItemAtPath:defaultDBPath toPath:_dbPath error:&error];

}  

}

Tell me if it helps!

Answer 2

try below code for find database path

    NSString *databaseName = @"your_db_name.sql";
    NSString *databasePath;
    // Get the path to the documents directory and append the databaseName
    NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDir = [documentPaths objectAtIndex:0];
    databasePath = [documentsDir stringByAppendingPathComponent:databaseName];
    NSLog(@"Database Path is: %@",databasePath);

You want More Detail about Sqllite Database Connectivity in iOS try this tutorial

Welcome!

Answer 3

If you created a sqlite db file and drag it to your project in xcode3, it's in application document folder while its running.

NSString *databaseName = @"cartoon.db";
NSArray *documentPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

NSString *documentDir = [documentPaths objectAtIndex:0];
NSString *databasePath = [documentDir stringByAppendingPathComponent:databaseName];

Answer 4

每当使用数据库时，都必须使用文档目录