我是 iOS 编程的新手。

通过使用下面的代码，我从数据库中检索图像并将其存储在数组中，然后以缩略图的形式显示这些图像。

通过使用下面的代码，一切正常。但我有两个问题

NSString *docsDir;
NSArray *dirPaths;

// Get the documents directory
dirPaths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);

docsDir = [dirPaths objectAtIndex:0];
array=[[NSMutableArray alloc]init];
array1=[[NSMutableArray alloc]init];

// Build the path to the database file
databasePath =  [docsDir stringByAppendingPathComponent: @"Taukydataaa.db"];

NSFileManager *fn=[NSFileManager defaultManager];
NSError *error;
BOOL success=[fn fileExistsAtPath:databasePath];

if(!success)
{    
    NSString *defaultDBPath = [[[NSBundle mainBundle] resourcePath] stringByAppendingPathComponent:@"Taukydataaa.db"];
    success = [fn copyItemAtPath:defaultDBPath toPath:databasePath error:&error];
}

const char *dbpath = [databasePath UTF8String];

sqlite3_stmt    *statement;

if (sqlite3_open(dbpath, &contactDB) == SQLITE_OK)
{
    NSString *querySQL = [NSString stringWithFormat: @"select * from tauky"];

    const char *query_stmt = [querySQL UTF8String];

    if (sqlite3_prepare_v2(contactDB, query_stmt, -1, &statement, NULL) == SQLITE_OK)
    {
        while(sqlite3_step(statement) == SQLITE_ROW)
        {

            NSString* email_idField = [[NSString alloc] initWithUTF8String:(const char *) sqlite3_column_text(statement,1)];
            NSString* email_idField1 = [[NSString alloc] initWithUTF8String:(const char *) sqlite3_column_text(statement,0)];
            [array addObject:email_idField];
            [array1 addObject:email_idField1];

            blaukypath =[[NSMutableArray alloc]init];

            for (NSString* path in array)
            {
                [blaukypath addObject:[UIImage imageWithContentsOfFile:path]];
            }

            myScrollView = [[UIScrollView alloc]initWithFrame:CGRectMake(0.0, 0.0, 320.0, 840.0)];
            myScrollView.delegate = self;
            myScrollView.contentSize = CGSizeMake(320.0, 840.0);
            myScrollView.backgroundColor = [UIColor whiteColor];

            [self.view addSubview:myScrollView];

            float horizontal = 8.0;
            float vertical = 8.0;

            for(int i=0; i<[blaukypath count]; i++)
            {
                if((i%4) == 0 && i!=0)
                {
                    horizontal = 8.0;
                    vertical = vertical + 70.0 + 8.0;
                }

                buttonImage = [UIButton buttonWithType:UIButtonTypeCustom];

                [buttonImage setFrame:CGRectMake(horizontal, vertical, 70.0, 70.0)];
                [buttonImage setTag:i];

                [buttonImage setImage:[blaukypath objectAtIndex:i] forState:UIControlStateNormal];
                [buttonImage addTarget:self action:@selector(buttonImagePressed:) forControlEvents:UIControlEventTouchUpInside];
                [buttonImage setImage:[UIImage imageNamed:@"play.png"] forState:UIControlStateSelected];

                [myScrollView addSubview:buttonImage];

                horizontal = horizontal + 70.0 + 8.0;
            }

            [myScrollView setContentSize:CGSizeMake(320.0, vertical + 78.0)];

            // Do any additional setup after loading the view, typically from a nib.
            self.navigationItem.leftBarButtonItem = self.editButtonItem;

            UIBarButtonItem *done = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemDone target:self action:@selector(insertNewObject:)];

            self.navigationItem.rightBarButtonItem = done;

            [self.myScrollView addSubview:image];
        }

        sqlite3_finalize(statement);
    }

    sqlite3_close(contactDB);
}

最佳答案

几个观察:

关于iphone - 在 iphone 中从数据库中检索图像花费的时间太长，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/15878873/