插入的NSData到iPhone上的SQLite [英] Inserting NSData into SQLite on the iPhone
问题描述
到目前为止,我已经成功地创建用于插入iPhone上的SQLite数据库这个方法:
So far I've managed to create this method for inserting into a SQLite database on the iPhone:
- (void) insertToDB :(NSString *)Identifier :(NSString *)Name
{
sqlite3 *database;
if(sqlite3_open([databasePath UTF8String], &database) == SQLITE_OK)
{
char *sql1 = "INSERT INTO table VALUES ('";
const char *sql2 = [Identifier cStringUsingEncoding:[NSString defaultCStringEncoding]];
char *sql3 = "', '";
const char *sql4 = [Name cStringUsingEncoding:[NSString defaultCStringEncoding]];
char *sql5 = "')";
char *sqlStatement[255];
strcpy(sqlStatement, sql1);
strcat(sqlStatement, sql2);
strcat(sqlStatement, sql3);
strcat(sqlStatement, sql4);
strcat(sqlStatement, sql5);
sqlite3_stmt *compiledStatement;
if(sqlite3_prepare_v2(database, sqlStatement, -1, &compiledStatement, NULL) == SQLITE_OK)
{
sqlite3_last_insert_rowid(database);
sqlite3_reset(compiledStatement);
}
sqlite3_finalize(compiledStatment);
}
sqlite3_close(database);
}
现在我期待在数据库中存储的图像。到目前为止,我已经<一个href=\"http://stackoverflow.com/questions/643682/reading-and-writing-images-to-an-sqlite-db-for-iphone-use\">found这:
Now I'm looking at storing an image in the database. So far I've found this:
UIImage *cachedImage = [UIImage imageNamed:@"Icon.png"];
NSData *dataForImage = UIImagePNGRepresentation(cachedImage);
但我遇到了麻烦试图将此NSData的插入字符数组,这使得将SQLStatement。任何人有一个想法如何做到这一点?
But i'm having trouble trying to insert this NSData into the char array which makes the sqlStatement. Anyone got an idea how to do this?
(我在BLOB类型的数据库中这个字段)。
(I have a field in the database of type blob for this).
感谢
推荐答案
我会使用 sqlite3_stmt
而不是字符串。然后,你可以使用 sqlite3_bind_blob
来的BLOB到prepared声明绑定。
I would use sqlite3_stmt
instead of a string. Then, you could use sqlite3_bind_blob
to bind the blob to the prepared statement.
sqlite3_stmt *insert_statement;
char *sql = "INSERT INTO table (blobcolumn, column2, column3) VALUES (? , ?, ?)" ;
if(sqlite3_prepare_v2(database, sql, -1, &insert_statement, NULL) != SQLITE_OK)
{
//handle error
}
sqlite3_bind_blob(insert_statement, 1, [dataForImage bytes], [dataForImage length], NULL);
不过,说真的,这将是最好的性能在磁盘上存储图像和数据库的路径。
But, really, it would be best for performance to store the image on disk and the path in the database.
另一种方式来做到这一点,一个我用的XML发送图像数据,是立足64 EN code中的数据。我在这里有它作为的NSString类别:
Another way to do it, one that I use to send image data in XML, is to base 64 encode the data. I have it here as a category on NSString:
static char base64EncodingTable[64] = {
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'
};
@implementation NSString (NSStringCategories)
+ (NSString *) base64StringFromData: (NSData *)data length: (int)length {
unsigned long ixtext, lentext;
long ctremaining;
unsigned char input[3], output[4];
short i, charsonline = 0, ctcopy;
const unsigned char *raw;
NSMutableString *result;
lentext = [data length];
if (lentext < 1)
return @"";
result = [NSMutableString stringWithCapacity: lentext];
raw = [data bytes];
ixtext = 0;
while (true) {
ctremaining = lentext - ixtext;
if (ctremaining <= 0)
break;
for (i = 0; i < 3; i++) {
unsigned long ix = ixtext + i;
if (ix < lentext)
input[i] = raw[ix];
else
input[i] = 0;
}
output[0] = (input[0] & 0xFC) >> 2;
output[1] = ((input[0] & 0x03) << 4) | ((input[1] & 0xF0) >> 4);
output[2] = ((input[1] & 0x0F) << 2) | ((input[2] & 0xC0) >> 6);
output[3] = input[2] & 0x3F;
ctcopy = 4;
switch (ctremaining) {
case 1:
ctcopy = 2;
break;
case 2:
ctcopy = 3;
break;
}
for (i = 0; i < ctcopy; i++)
[result appendString: [NSString stringWithFormat: @"%c", base64EncodingTable[output[i]]]];
for (i = ctcopy; i < 4; i++)
[result appendString: @"="];
ixtext += 3;
charsonline += 4;
if ((length > 0) && (charsonline >= length))
charsonline = 0;
}
return result;
}
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