iphone - 如何在委托(delegate)和 Controller 文件中使用自定义数据库 header 的相同对象？

Question

全部我想为这样的数据库创建头文件。它包含以下六个文件。

数据库.h

    #import <Foundation/Foundation.h>
    #import "sqlite3.h"
    @interface Database : NSObject 
    {
      sqlite3 *mydb;
    }

    -(void) openDB;
    -(NSString *) filePath;
    -(BOOL) createTable;
    +(Database*)sharedInstance;
    @end

数据库.m #导入“数据库.h”

    @implementation Database
    static Database* dbase = nil;

    +(Database*)sharedInstance
    {
        if (dbase == nil)
        {
                 dbase = [[Database alloc] init];
        }
        return dbase;
    }

    -(NSString *) filePath{
NSArray *paths =NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES);
NSString *documentsDir = [paths objectAtIndex:0];
NSLog(@"DBPATH:%@",documentsDir);
return [documentsDir stringByAppendingPathComponent:@"userdb.sqlite"];

    }

    -(void) openDB {
         if (sqlite3_open([[self filePath]UTF8String],&mydb) != SQLITE_OK) {
                 sqlite3_close(mydb);
                 NSAssert(0,@"Database failed to Open ...");
          }
         BOOL result = [self createTable];
         NSLog(@"Table Avi gayu 6...!!! %u",result);

    }

   - (BOOL) createTable
   {
     sqlite3_stmt *createStmt;
     createStmt = nil;
     NSString *tableName = @"user_table";

     if ( createStmt == nil )
     {
        NSString *query = [NSString stringWithFormat:@"create table if not exists %@ \
                       (userid      INTEGER PRIMARY KEY, \
                       name     TEXT NOT NULL)",tableName];
            if (sqlite3_prepare_v2(mydb, [query UTF8String], -1, &createStmt, NULL)!= SQLITE_OK ) 
           {
               return NO;
           }
           sqlite3_exec(mydb, [query UTF8String], NULL, NULL, NULL);
           return YES;
       }
      return YES;
   }

  @end

UIDBDemoAppDelegate.h

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

  @class UIDBDemoViewController;

   @interface UIDBDemoAppDelegate : NSObject <UIApplicationDelegate> {
        UIWindow *window;
        UIDBDemoViewController *viewController;

  }

  @property (nonatomic, retain) IBOutlet UIWindow *window; 
  @property (nonatomic, retain) IBOutlet UIDBDemoViewController *viewController;

  @end

UIDBDemoAppDelegate.m

    #import "UIDBDemoAppDelegate.h"
    #import "UIDBDemoViewController.h"

   @implementation UIDBDemoAppDelegate

   @synthesize window; 
   @synthesize viewController;



   #pragma mark -
   #pragma mark Application lifecycle

   - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {    
              [[Database sharedInstance] openDB];
                  [self.window addSubview:viewController.view];
                  [self.window makeKeyAndVisible];

                  return YES; }

    - (void)applicationWillResignActive:(UIApplication *)application { }


    - (void)applicationDidEnterBackground:(UIApplication *)application { }


    - (void)applicationWillEnterForeground:(UIApplication *)application { }


    - (void)applicationDidBecomeActive:(UIApplication *)application { }


     - (void)applicationWillTerminate:(UIApplication *)application { }


    #pragma mark -
    #pragma mark Memory management

    - (void)applicationDidReceiveMemoryWarning:(UIApplication *)application { }


    - (void)dealloc {
        [viewController release];
        [window release];
        [super dealloc]; }


      @end

UIDBDemoViewController.h

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

@interface UIDBDemoViewController : UIViewController
<UITableViewDataSource> {      
      UIView *addView;    
      UILabel *uid,*unm,*cellLbl1,*cellLbl2;  
      UITextField *txtuid,*txtunm;    
      UIButton *btnadd,*btnshow;  
      UITableView *mytabView;
      NSMutableArray *uidarray,*unmarray;  
   }
@property (retain, nonatomic) UIView *addView; 
@property (retain, nonatomic) UILabel *uid,*unm; @property (retain, nonatomic) UITextField *txtuid,*txtunm;
 @property (retain, nonatomic) UIButton *btnadd,*btnshow;
-(void) addClicked;
-(void) showClicked;
-(void) readData;
-(void) rmkeyboard;
   @end

UIDBDemoViewController.m

#import "UIDBDemoViewController.h"


@implementation UIDBDemoViewController
@synthesize addView, uid,unm,txtuid,txtunm,btnadd,btnshow;

 - (void)loadView
 {


     //Add myView 
     CGRect rect = CGRectMake(0, 0, 320, 480);
     addView = [[UIView alloc] initWithFrame:rect];
     addView.backgroundColor=[UIColor blackColor];

    //Adding two Name and Password Label into myView
    uid=[[UILabel alloc] initWithFrame:CGRectMake(20, 100, 100, 35)];
    uid.text=@"User ID:";
    uid.textAlignment=UITextAlignmentRight;
    uid.textColor=[UIColor whiteColor];
    uid.backgroundColor=[UIColor blackColor];
    [addView addSubview:uid];

    unm=[[UILabel alloc] initWithFrame:CGRectMake(20, 140, 100, 35)];
    unm.text=@"User Name:";
    unm.textAlignment=UITextAlignmentRight;
    unm.textColor=[UIColor whiteColor];
    unm.backgroundColor=[UIColor blackColor];
    [addView addSubview:unm];


     //Adding Two Name and Password TextField into myView
    txtuid=[[UITextField alloc] initWithFrame:CGRectMake(130, 100, 150, 30)]; 
    txtuid.placeholder=@"Enter User ID";
    txtuid.borderStyle=UITextBorderStyleRoundedRect;
    [txtuid addTarget:self action:@selector(rmkeyboard) forControlEvents:UIControlEventEditingDidEndOnExit];
    [addView addSubview:txtuid];

    txtunm=[[UITextField alloc] initWithFrame:CGRectMake(130, 140, 150, 30)];
    txtunm.placeholder=@"Enter User Name";
    txtunm.borderStyle=UITextBorderStyleRoundedRect;
    [txtunm addTarget:self action:@selector(rmkeyboard) forControlEvents:UIControlEventEditingDidEndOnExit];
    [addView addSubview:txtunm];


//Adding Two Button Login and Cancel into myView
    btnadd=[UIButton buttonWithType:UIButtonTypeRoundedRect]; 
    btnadd.frame=CGRectMake(50, 200, 100, 35);
    [btnadd setTitle:@"ADD" forState:UIControlStateNormal];
    [btnadd addTarget:self action:@selector(addClicked) forControlEvents:UIControlEventTouchUpInside];
    [addView addSubview:btnadd];

    btnshow=[UIButton buttonWithType:UIButtonTypeRoundedRect];
    btnshow.frame=CGRectMake(180, 200, 100, 35);
    [btnshow setTitle:@"SHOW" forState:UIControlStateNormal];
    [btnshow addTarget:self action:@selector(showClicked) forControlEvents:UIControlEventTouchUpInside];
    [addView addSubview:btnshow];

    self.view=addView;


}

-(void) rmkeyboard
{
    [txtuid resignFirstResponder];
    [txtunm resignFirstResponder];
}
-(void)readData
{
    NSString *query = [NSString stringWithString:@"select * from user_table"];
    sqlite3_stmt *selectStatement;

    uidarray = [[NSMutableArray alloc] init];
    unmarray = [[NSMutableArray alloc] init];
    int userid;
    NSString *username;

    int i=0;
    if (sqlite3_prepare_v2([Database sharedInstance], [query UTF8String], -1, &selectStatement, NULL) == SQLITE_OK)
    {
         while (sqlite3_step(selectStatement)== SQLITE_ROW)
        {
            userid = sqlite3_column_int(selectStatement, 0);
             username = [NSString stringWithUTF8String:(char *)sqlite3_column_text(selectStatement, 1)];


            [uidarray addObject:[NSString stringWithFormat:@"%d",userid]];
            [unmarray addObject:username];

            NSLog(@"id=%@",[uidarray objectAtIndex:i]);

            NSLog(@"unm=%@",[unmarray objectAtIndex:i]);
            i++;

        }
        sqlite3_finalize(selectStatement);
        }
}

-(void) showClicked
{
    printf("Hello... showClicked");
    //Tableview
    mytabView = [[[UITableView alloc] initWithFrame:CGRectMake(0, 20, 320, 300) style:UITableViewStylePlain] autorelease];
    [mytabView setDataSource:self];
    [addView addSubview:mytabView];
    [self readData];

}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return [uidarray count];
}
// Return a cell for the specified index path
 - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"any-cell"];
    if (cell == nil) 
    { 
        cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:@"any-cell"] autorelease];
    }   

    CGFloat height=[tableView rowHeight];
    cellLbl1=[[UILabel alloc]initWithFrame:CGRectMake(20, 0,60, height)];
    cellLbl2=[[UILabel alloc]initWithFrame:CGRectMake(150, 0,100, height)];
    cellLbl1.text=[uidarray objectAtIndex:[indexPath row]];
    cellLbl2.text=[unmarray objectAtIndex:[indexPath row]];
    [cell addSubview:cellLbl1];
    [cell addSubview:cellLbl2];
    return cell;
}

-(void) addClicked
{
    NSLog(@"Add Dabavyu...");
    sqlite3_stmt *insertStmt;

    NSString *suid = txtuid.text;
    NSInteger iuid = [suid intValue];

    NSString *sunm = [NSString stringWithFormat:@"%@",txtunm.text];

    NSString *insertQuery = [NSString stringWithFormat:@"insert into user_table values (%d,'%@');",iuid,sunm];

    NSLog(@"int Query= %@",insertQuery);

    if (sqlite3_prepare_v2([Database sharedInstance], [insertQuery UTF8String], -1, &insertStmt, NULL) != SQLITE_OK)
    {
        NSLog(@"Inserting Failed....!!!!");
        return;
    }

    sqlite3_exec([Database sharedInstance], [insertQuery UTF8String], NULL, NULL, NULL);

}



- (void)didReceiveMemoryWarning
{
        [super didReceiveMemoryWarning];
}

- (void)viewDidUnload { }


- (void)dealloc {
    [super dealloc];
}

@end

我想在 Controller 文件中使用同一个对象将数据插入数据库表user_table。我已经给出了应用程序的完整源代码。

我收到警告从不兼容的指针类型传递'sqlite3_prepare_v2'的参数1并且因此我无法从cnrtl文件打开到数据库的连接，请指导我如何解决它。

请帮助我。我是 iPhone 编程的初学者。

Answer 1

创建一个单例对象，如下所示:

在头文件中:

+(Database*)sharedInstance;

在实现文件中:

static Database* dbase = nil;

+(Database*)sharedInstance
{
     if (dbase == nil)
     {
        dbase = [[Database alloc] init];
     }
     return dbase;
}

当你想调用数据库时，只需使用方法获取数据库对象
[数据库共享实例]