sqlite中的图像检索

Question

我在我的项目中使用sqlite

以前我将图像保存在数据中，但现在我像下面的代码一样将图像保存在字节中

NSUInteger len = [entObject.photoImageData length];  
 Byte *byteData = (Byte*)malloc(len);  
 memcpy(byteData, [entObject.photoImageData bytes], len);  
insertString = [NSString stringWithFormat:@"INSERT INTO TBL_COUNTDOWN (DAIRYID,EVENTID,DESCRIPTION,EVENTIMAGE) VALUES (\"%@\",\"%d\",\"No Data\",\"%s\")",self.dairyId,self.eventId,byteData];

为了检索图像，我使用了以下代码

NSData *dataForCachedImage = [[NSData alloc] initWithBytes:sqlite3_column_blob(statement, 3) length: sqlite3_column_bytes(statement, 3)];  
                    NSLog(@"dataForCachedImage/getAllEvents is %@",dataForCachedImage);  
                    UIImage *cachedImage = [UIImage imageWithData:dataForCachedImage];  
                    NSLog(@"cachedImage/getAllEvents is %@",cachedImage);

对于NSLog中的dataForCachedImage，我获取的是数据，但对于cachedImage，我获取的是null

我不知道我的代码有什么问题。请帮帮我

提前感谢

Answer 1

您可以将图像保存到文档目录，并将其路径存储到sqlite数据库保存图像代码如下

 #define DOCUMENTS_FOLDER [NSHomeDirectory() stringByAppendingPathComponent:@"Documents"]

 // Create a new dated file
 NSDate *now = [NSDate dateWithTimeIntervalSinceNow:0];
 NSString *caldate = [now description];

 NSString *filePath= [NSString stringWithFormat:@"%@/%@.jpg", DOCUMENTS_FOLDER,caldate];
 NSURL *url = [NSURL fileURLWithPath:filePath];

 UIImage *image = [UIImage imageNamed:@"name.jpg"];
 NSData *imageData = UIImagePNGRepresentation(image);

 [imageData writeToFile:filePath atomically:YES];

任何时候你想检索图片，然后获取它，然后使用下面的方法来getImage

- (UIImage*)getImage
{
 NSString *imagePath = [DOCUMENTS_FOLDER stringByAppendingPathComponent:@"imagename.jpg"];
 UIImage *img = [UIImage imageWithContentsOfFile:imagePath];
 return img;
}

正在删除文件

  NSFileManager *fileManager=[NSFileManager defaultManager];
  [fileManager removeItemAtPath:savedFilePath error:nil];

愿这篇文章能帮助你..