iOS - SQLite 資料庫

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SQLite 可用於 iOS 中的資料處理。它使用 sqlite 查詢，對於熟悉 SQL 的人來說更容易。

步驟

步驟 1 - 建立一個簡單的基於檢視的應用程式。

步驟 2 - 選擇您的專案檔案，然後選擇目標，然後在選擇框架中新增libsqlite3.dylib庫。

步驟 3 - 透過選擇檔案→新建→檔案...→選擇Objective C 類並點選下一步來建立一個新檔案。

步驟 4 - 將類命名為DBManager，“子類”為 NSObject。

步驟 5 - 選擇建立。

步驟 6 - 更新DBManager.h如下：

#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

步驟 7 - 更新DBManager.m如下：

#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;
}

步驟 8 - 更新ViewController.xib檔案如下：

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步驟 9 - 為上述文字欄位建立 IBOutlets。

步驟 10 - 為上述按鈕建立 IBAction。

步驟 11 - 更新ViewController.h如下：

#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

步驟 12 - 更新ViewController.m如下：

#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

輸出

執行應用程式後，我們將獲得以下輸出，我們可以在其中新增和查詢學生詳細資訊：

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