iOS SQLite database

IOS SQLite database

Brief introduction

Use Sqlite to process data in IOS. If you already know SQL, you can easily master the operation of the SQL database.

The instance step

1, create a simple View base application

2, select the project file, and then select the target, add libsqlite3.dylib library to the selection framework

3. Create a new file by selecting "File-New-New-File...", click Next

4, "sub class of" for NSObject, class named DBManager

5, choose to create

6, update DBManager.h, as shown below

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

@interface DBManager : NSObject
{
    NSString *databasePath;
}

+(DBManager*)getSharedInstance;
-(BOOL)createDB;
-(BOOL) saveData:(NSString*)registerNumber name:(NSString*)name 
  department:(NSString*)department year:(NSString*)year;
-(NSArray*) findByRegisterNumber:(NSString*)registerNumber;

@end

7, update the DBManager .m, as shown below

#import "DBManager.h"
static DBManager *sharedInstance = nil;
static sqlite3 *database = nil;
static sqlite3_stmt *statement = nil;

@implementation DBManager

+(DBManager*)getSharedInstance{
    if (!sharedInstance) {
        sharedInstance = [[super allocWithZone:NULL]init];
        [sharedInstance createDB];
    }
    return sharedInstance;
}

-(BOOL)createDB{
    NSString *docsDir;
    NSArray *dirPaths;    
    // Get the documents directory
    dirPaths = NSSearchPathForDirectoriesInDomains
    (NSDocumentDirectory, NSUserDomainMask, YES);    
    docsDir = dirPaths[0];
    // Build the path to the database file
    databasePath = [[NSString alloc] initWithString: 
    [docsDir stringByAppendingPathComponent: @"student.db"]];
    BOOL isSuccess = YES;
    NSFileManager *filemgr = [NSFileManager defaultManager];    
    if ([filemgr fileExistsAtPath: databasePath ] == NO)
    {
        const char *dbpath = [databasePath UTF8String];        
        if (sqlite3_open(dbpath, &database) == SQLITE_OK)
        {
            char *errMsg;
            const char *sql_stmt =
            "create table if not exists studentsDetail (regno integer 
            primary key, name text, department text, year text)";            
            if (sqlite3_exec(database, sql_stmt, NULL, NULL, &errMsg) 
               != SQLITE_OK)
            {
                isSuccess = NO;
                NSLog(@"Failed to create table");
            }
            sqlite3_close(database);
            return  isSuccess;
        }
        else {
            isSuccess = NO;
            NSLog(@"Failed to open/create database");
        }
    }    
    return isSuccess;
}

- (BOOL) saveData:(NSString*)registerNumber name:(NSString*)name 
  department:(NSString*)department year:(NSString*)year;
{
    const char *dbpath = [databasePath UTF8String];    
    if (sqlite3_open(dbpath, &database) == SQLITE_OK)
    {        
        NSString *insertSQL = [NSString stringWithFormat:@"insert into
        studentsDetail (regno,name, department, year) values
        (\"%d\",\"%@\", \"%@\", \"%@\")",[registerNumber integerValue],
        name, department, year];        
        const char *insert_stmt = [insertSQL UTF8String];
        sqlite3_prepare_v2(database, insert_stmt,-1, &statement, NULL);
        if (sqlite3_step(statement) == SQLITE_DONE)
        {
            return YES;
        } 
        else {
            return NO;
        }
        sqlite3_reset(statement);
    }
    return NO;
}

- (NSArray*) findByRegisterNumber:(NSString*)registerNumber
{
    const char *dbpath = [databasePath UTF8String];    
    if (sqlite3_open(dbpath, &database) == SQLITE_OK)
    {
        NSString *querySQL = [NSString stringWithFormat:
        @"select name, department, year from studentsDetail where 
        regno=\"%@\"",registerNumber];        
        const char *query_stmt = [querySQL UTF8String];
        NSMutableArray *resultArray = [[NSMutableArray alloc]init];
        if (sqlite3_prepare_v2(database,
           query_stmt, -1, &statement, NULL) == SQLITE_OK)
        {
            if (sqlite3_step(statement) == SQLITE_ROW)
            {                
                NSString *name = [[NSString alloc] initWithUTF8String:
                 (const char *) sqlite3_column_text(statement, 0)];
                [resultArray addObject:name];
                NSString *department = [[NSString alloc] initWithUTF8String:
                (const char *) sqlite3_column_text(statement, 1)];
                [resultArray addObject:department];
                NSString *year = [[NSString alloc]initWithUTF8String:
                (const char *) sqlite3_column_text(statement, 2)];
                [resultArray addObject:year];
                return resultArray;
            }
            else{
                NSLog(@"Not found");
                return nil;
            }
            sqlite3_reset(statement);
        }
    }
    return nil;
}

8, as shown, update the ViewController.xib file

9. Create IBOutlets for the above text fields

10. Create IBAction for the above buttons

11, as shown below, update ViewController.h

#import <UIKit/UIKit.h>
#import "DBManager.h"

@interface ViewController : UIViewController<UITextFieldDelegate>
{
    IBOutlet UITextField *regNoTextField;
    IBOutlet UITextField *nameTextField;
    IBOutlet UITextField *departmentTextField;
    IBOutlet UITextField *yearTextField;
    IBOutlet UITextField *findByRegisterNumberTextField;
    IBOutlet UIScrollView *myScrollView;
}

-(IBAction)saveData:(id)sender;
-(IBAction)findData:(id)sender;

@end

12, update the ViewController .m, as shown below

#import "ViewController.h"

@interface ViewController ()

@end

@implementation ViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)
  nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        // Custom initialization
    }
    return self;
}

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

- (void)didReceiveMemoryWarning
{
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}

-(IBAction)saveData:(id)sender{
    BOOL success = NO;
    NSString *alertString = @"Data Insertion failed";
    if (regNoTextField.text.length>0 &&nameTextField.text.length>0 &&
    departmentTextField.text.length>0 &&yearTextField.text.length>0 )
    {
        success = [[DBManager getSharedInstance]saveData:
        regNoTextField.text name:nameTextField.text department:
        departmentTextField.text year:yearTextField.text];
    }
    else{
        alertString = @"Enter all fields";
    }     
    if (success == NO) {
        UIAlertView *alert = [[UIAlertView alloc]initWithTitle:
        alertString message:nil
        delegate:nil cancelButtonTitle:@"OK" otherButtonTitles:nil];
        [alert show];
    }
}

-(IBAction)findData:(id)sender{
    NSArray *data = [[DBManager getSharedInstance]findByRegisterNumber:
    findByRegisterNumberTextField.text];
    if (data == nil) {
        UIAlertView *alert = [[UIAlertView alloc]initWithTitle:
        @"Data not found" message:nil delegate:nil cancelButtonTitle:
        @"OK" otherButtonTitles:nil];
        [alert show];
        regNoTextField.text = @"";
        nameTextField.text =@"";
        departmentTextField.text = @"";
        yearTextField.text =@"";
    }
    else{
        regNoTextField.text = findByRegisterNumberTextField.text;
        nameTextField.text =[data objectAtIndex:0];
        departmentTextField.text = [data objectAtIndex:1];
        yearTextField.text =[data objectAtIndex:2];
    }
}

#pragma mark - Text field delegate
-(void)textFieldDidBeginEditing:(UITextField *)textField{
    [myScrollView setFrame:CGRectMake(10, 50, 300, 200)];
    [myScrollView setContentSize:CGSizeMake(300, 350)];
}
-(void)textFieldDidEndEditing:(UITextField *)textField{
    [myScrollView setFrame:CGRectMake(10, 50, 300, 350)];

}
-(BOOL) textFieldShouldReturn:(UITextField *)textField{
    
    [textField resignFirstResponder];
    return YES;
}
@end

Output

Now when we run the application, we get the following output, where we can add and find student details