在iOS中启动应用程序时如何复制sqlite数据库？

Posted 2023-03-22

【中文标题】在iOS中启动应用程序时如何复制sqlite数据库？

【英文标题】：How to copy sqlite database when application is launched in iOS?

【发布时间】：2013-03-07 15:22:02

【问题描述】：

我想在每次启动应用程序时将我的 sqlite 数据库从数据库位置复制到我的 ios 应用程序的最新更新。

有什么办法吗？

【问题讨论】：

请确保对于此类问题，您确实列出了对您尝试过的资源的引用，或者只是在这里写下您的代码，以便每个人都知道您的方法/方法

【参考方案1】：

您可以将以下方法添加到您的 appdelegate

- (void) copyDatabaseIfNeeded 

    //Using NSFileManager we can perform many file system operations.
    NSFileManager *fileManager = [NSFileManager defaultManager];
    NSError *error;

    NSString *dbPath = [self getDBPath];
    BOOL success = [fileManager fileExistsAtPath:dbPath];

    if(!success) 

       NSString *defaultDBPath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"database.sqlite"];
       success = [fileManager copyItemAtPath:defaultDBPath toPath:dbPath error:&error];

       if (!success)
          NSAssert1(0, @"Failed to create writable database file with message '%@'.", [error localizedDescription]);
    


- (NSString *) getDBPath
   
    //Search for standard documents using NSSearchPathForDirectoriesInDomains
    //First Param = Searching the documents directory
    //Second Param = Searching the Users directory and not the System
    //Expand any tildes and identify home directories.

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory , NSUserDomainMask, YES);
    NSString *documentsDir = [paths objectAtIndex:0];
    //NSLog(@"dbpath : %@",documentsDir);
    return [documentsDir stringByAppendingPathComponent:@"database.sqlite"];

并在您的启动方法中调用此方法 [self copyDatabaseIfNeeded];希望这会有所帮助。

【讨论】：

不，如果您的原始数据库很脏，您希望保留用户活动数据而不是覆盖整个数据库。

新替换的数据库是否可写？我已经替换了一个数据库，但它变成了只读的。我怎样才能让它可写？

对于其他来到这里并需要表格数据的人您还需要复制.sqlite-wal 和.sqlite-shm 文件。

【参考方案2】：

试试这个：

NSArray *docPath = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *strDocDirectory = [docPath objectAtIndex:0];

    self.strDatabasePath = [strDocDirectory stringByAppendingPathComponent:YOUR_DB];


    NSFileManager *filemgr = [NSFileManager defaultManager];

    if ([filemgr fileExistsAtPath: self.strDatabasePath ] == NO)
    
        const char *dbpath = [self.strDatabasePath UTF8String];
        sqlite3 *contactDB;


        if (sqlite3_open(dbpath, &contactDB) == SQLITE_OK)
        
            char *errMsg;
            const char *sql_stmt = "CREATE TABLE IF NOT EXISTS YOUR_Table (ID INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT)";

            if (sqlite3_exec(contactDB, sql_stmt, NULL, NULL, &errMsg) != SQLITE_OK)
            
                NSLog(@"Failed to create table");
            

            sqlite3_close(contactDB);

【参考方案3】：

在 AppDelegate 类

中试试这个

.h 文件

@property(nonatomic, retain) NSString *dbPath;

.m 文件

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions

    [self copyDatabaseIfNeeded];

- (void) copyDatabaseIfNeeded

    NSFileManager *fileManager = [NSFileManager defaultManager];
    NSError *error;
    dbPath = [self getDBPath];

    BOOL success = [fileManager fileExistsAtPath:dbPath];

    if(!success)
    
       NSString *defaultDBPath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"sampleDB.sqlite3"];
       success = [fileManager copyItemAtPath:defaultDBPath toPath:dbPath error:&error];
       if (!success)
          NSAssert1(0, @"Failed to create writable database file with message '%@'.", [error localizedDescription]);
    


/********* Database Path *********/
- (NSString *) getDBPath

    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,NSUserDomainMask,YES);
    NSString *documentsDir = [paths objectAtIndex:0];

    return [documentsDir stringByAppendingPathComponent:@"sampleDB.sqlite3"];

如果在应用程序中没有找到任何数据库，它会自动复制。

希望对你有所帮助。

谢谢。

【讨论】：

试试这个，一定能帮到你。

【参考方案4】：

在应用程序启动时使用以下代码处理数据库

在您的 appdelegate.m 中

在

-(BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions

  [self getdatabase];

  return YES;

并将以下函数添加到您的 appdelegate.m

-(void)getdatabase

    BOOL success;
    NSFileManager *filemanager = [NSFileManager defaultManager];
    NSError *error;
    NSArray *pathArray = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *DBPath = [pathArray objectAtIndex:0];
    NSString *writableDBPath = @"";
    writableDBPath = [DBPath stringByAppendingPathComponent:@"xyz.sqlite"];
    NSLog(@"writableDBPath:%@",writableDBPath);
    success = [filemanager fileExistsAtPath:writableDBPath];
    if (!success) 
        NSString *defaultDBpath = [[[NSBundle mainBundle]resourcePath]stringByAppendingPathComponent:@"xyz.sqlite"];
       success = [filemanager copyItemAtPath:defaultDBpath toPath:writableDBPath error:&error];
       if (!success) 
            NSAssert(0, @"failed to copy database at path with message '%@'.",[error localizedDescription]); 
        
         
    NSLog(@"111writableDBPath:%@",writableDBPath);    

【参考方案5】：

-(void)openDatase  
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);  
    NSString *documentsDirectory = [paths objectAtIndex:0];  
    self.databasePath = [documentsDirectory stringByAppendingPathComponent:@"weightCal.sqlite"];  
    if (sqlite3_open([databasePath UTF8String], &database) == SQLITE_OK)   
        NSLog(@"Database Successfully Opened ");  
     else    
        NSLog(@"Error in opening database ");  
      


-(void)dealloc
    sqlite3_close(database);
    [super dealloc];



-(void)copyDatabase 
    BOOL success;
    NSFileManager *fileManager=[NSFileManager defaultManager];
    NSError *error;
    NSArray *paths= NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory=[paths objectAtIndex:0];
    NSString *writablePath = [documentsDirectory stringByAppendingPathComponent:@"test.sqlite"];
    success = [fileManager fileExistsAtPath:writablePath];
    if(success) 
       return;
    
    NSString *defaultPath=[[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"test.sqlite"];
    success=[fileManager copyItemAtPath:defaultPath toPath:writablePath error:&error];
    if(!success)
       NSAssert1(0,@"Failed to create writable database file with message '%@' .",[error localizedDescription]);
    

在.h 中声明以下 teo 变量：

sqlite3 *database; 
NSString *databasePath;

【参考方案6】：

这里是 Swift 4/5

    func copyDatabaseIfNeeded(sourcePath : String) -> Bool 
      var destPath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true).first!
      destPath = destPath + "/foo.db3"
      let databaseExistsWhereNeeded = FileManager.default.fileExists(atPath: destPath)
      if (!databaseExistsWhereNeeded) 
        do 
            try FileManager.default.copyItem(atPath: sourcePath, toPath: destPath)
            print("db copied")
        
        catch 
            print("error during file copy: \(error)")
        
    
    return true

【讨论】：

我的类似代码在 Xcode 11.4 中编译良好 - 所以，是的 - 如果您遇到问题，请告诉我。

非常感谢。它似乎工作正常。我只是想知道 Swift 5 是否允许将其优化为更少的行或任何东西。感谢您的回答