【发布时间】：2014-03-13 14:18:19
【问题描述】：
我有一个带有 select 语句的函数，它从一个表中获取一些信息，并使用该信息的一部分来使用另一个 select 语句从另一个表中获取更多信息。然后该函数将两个表中的信息添加到对象数组中。
看起来很简单，但是每次加载使用该函数的 ViewController 时，内存使用量都会上升，并且再也不会下降。如果我注释掉对这个函数的调用，那么内存使用情况就很好了。
-(void)displayExhibitor
{
arrayOfExhibitors = [[NSMutableArray alloc] init];
if (sqlite3_open([[self filePath] UTF8String], &congressDB) == SQLITE_OK){
sqlite3_stmt *sqlStatementExhibitor;
NSString *sqlQuery = [NSString stringWithFormat:@"SELECT * FROM Exhibitor ORDER BY Name"];
const char *sqlQueryChars = [sqlQuery UTF8String];
if (sqlite3_prepare(congressDB, sqlQueryChars, -1, &sqlStatementExhibitor, NULL)==SQLITE_OK) {
while (sqlite3_step(sqlStatementExhibitor)==SQLITE_ROW) {
NSString *name = [[NSString alloc] initWithUTF8String:(const char *)sqlite3_column_text(sqlStatementExhibitor, 1)];
NSString *category = [[NSString alloc] initWithUTF8String:(const char *)sqlite3_column_text(sqlStatementExhibitor, 4)];
NSString *description = [[NSString alloc] initWithUTF8String:(const char *)sqlite3_column_text(sqlStatementExhibitor, 5)];
NSString *locationID = [[NSString alloc] initWithUTF8String:(const char *)sqlite3_column_text(sqlStatementExhibitor, 3)];
NSString *location;
// Get exhibitor location information from location table
sqlite3_stmt *sqlStatementLocation;
NSString *sqlQueryLocation = [NSString stringWithFormat:@"SELECT Name FROM Location WHERE _ID = '%@'", locationID];
const char *sqlQueryCharsLocation = [sqlQueryLocation UTF8String];
if (sqlite3_prepare(congressDB, sqlQueryCharsLocation, -1, &sqlStatementLocation, NULL)==SQLITE_OK) {
while (sqlite3_step(sqlStatementLocation)==SQLITE_ROW) {
location = [[NSString alloc] initWithUTF8String:(const char *)sqlite3_column_text(sqlStatementLocation, 0)];
}
} else {
NSLog(@"There was a problem with get location - %s",sqlite3_errmsg(congressDB));
}
sqlite3_finalize(sqlStatementLocation);
Exhibitor *exhibitor = [[Exhibitor alloc] init];
[exhibitor setName:name];
[exhibitor setCategory:category];
[exhibitor setDescription:description];
[exhibitor setLocation:location];
[arrayOfExhibitors addObject:exhibitor];
}
} else {
NSLog(@"There was a problem with prepare- %s",sqlite3_errmsg(congressDB));
}
sqlite3_finalize(sqlStatementExhibitor);
} else {
NSLog(@"There was a problem with DB open - %s",sqlite3_errmsg(congressDB));
}
[[self tableView]reloadData];
}
是因为我在另一个里面有一个 SQLite3_prepare 吗？
编辑： 我刚刚尝试将代码精简到最低限度：
-(void)testFunction
{
sqlite3_stmt *sqlStatementExhibitor;
NSString *sqlQuery = [NSString stringWithFormat:@"SELECT * FROM Exhibitor ORDER BY Name"];
const char *sqlQueryChars = [sqlQuery UTF8String];
if (sqlite3_open([[self filePath] UTF8String], &congressDB) == SQLITE_OK){
if (sqlite3_prepare(congressDB, sqlQueryChars, -1, &sqlStatementExhibitor, NULL)==SQLITE_OK) {
while (sqlite3_step(sqlStatementExhibitor)==SQLITE_ROW) {
NSLog(@"Row found");
}
} else {
NSLog(@"There was a problem with prepare- %s",sqlite3_errmsg(congressDB));
}
sqlite3_finalize(sqlStatementExhibitor);
}
}
每次运行时仍然会增加大约 250KB 的内存使用量，这是怎么回事？有没有办法可以手动从内存中释放 SQL 连接？
【问题讨论】：
-
这就是全部功能吗？
-
是的，就是这样。整个 ViewController.m 文件有更多代码，但这似乎是罪魁祸首，即如果我将其注释掉，内存问题就会消失。
标签： ios cocoa-touch memory-leaks sqlite