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iOS SQLite数据库

iOS开发手册

简介

在IOS中使用Sqlite来处理数据。如果你已经了解了SQL,那你可以很容易的掌握SQLite数据库的操作。

实例步骤

1、创建一个简单的View based application

2、选择项目文件,然后选择目标,添加libsqlite3.dylib库到选择框架

3、通过选择" File-> New -> File... -> "选择 Objective C class 创建新文件,单击下一步

4、"sub class of"为NSObject",类命名为DBManager

5、选择创建

6、更新DBManager.h,如下所示

#import

#import

@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、更新DBManager.m,如下所示

#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、如图所示,更新ViewController.xib文件

9、为上述文本字段创建IBOutlets

10、为上述按钮创建IBAction

11、如下所示,更新ViewController.h

#import

#import "DBManager.h"

@interface ViewController : UIViewController

{

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、更新ViewController.m,如下所示

#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

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