我想问用户是否想将他的分数从游戏添加到高分,在输入中我想问他的名字。在他完成后,我有这样的代码:
ListOfScores *listOfScores =[[ListOfScores alloc] init];
if ([listOfScores GetScoresCount] < 10) {
[self ShowMessageBoxForHighScore];
}
else if([listOfScores GetLastScore] < self.ActualScore)
{
[self ShowMessageBoxForHighScore];
}
- (void)ShowMessageBoxForHighScore
{
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"save score" message:@"input username:" delegate:self cancelButtonTitle:@"cancel" otherButtonTitles:nil];
alert.alertViewStyle = UIAlertViewStylePlainTextInput;
alert.tag = 12;
[alert addButtonWithTitle:@"save"];
[alert show];
}
- (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex
{
if (alertView.tag == 12) {
if (buttonIndex == 1) {
UITextField *textfield = [alertView textFieldAtIndex:0];
ListOfScores *listOfScores =[[ListOfScores alloc] init];
Score* score = [[Score alloc] initWithName:textfield.text Points:self.ActualScore];
[listOfScores AddScore:score];
}
}
}
以下是我检查和创建数据库的方法:
-(BOOL)CreateTableForScores {
BOOL ret;
int rc;
// SQL to create new table
NSString *sql_str = @"CREATE TABLE Scores (pk INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL , Points INTEGER DEFAULT 0, Name VARCHAR(100))";
const char *sqlStatement = (char *)[sql_str UTF8String];
NSLog(@"query %s",sqlStatement);
sqlite3_stmt *stmt;
rc = sqlite3_prepare_v2(db, sqlStatement, -1, &stmt, NULL);
ret = (rc == SQLITE_OK);
if (ret)
{ // statement built, execute
rc = sqlite3_step(stmt);
ret = (rc == SQLITE_DONE);
}
sqlite3_finalize(stmt); // free statement
NSLog(@"creating table");
return ret;
}
-(BOOL)TableForScoresExists {
sqlite3_stmt *statementChk;
sqlite3_prepare_v2(db, "SELECT name FROM sqlite_master WHERE type='table' AND name='Scores';", -1, &statementChk, nil);
bool boo = FALSE;
if (sqlite3_step(statementChk) == SQLITE_ROW) {
boo = TRUE;
}
sqlite3_finalize(statementChk);
return boo;
}
和我的 AddScore 方法:
- (void) AddScore:(Score *)newScore
{
@try {
BOOL tableExists = self.TableForScoresExists;
if(!tableExists)
{
tableExists = self.CreateTableForScores;
}
if(tableExists)
{
NSString *filename = @"database.sqlite";
NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *bundlePath = [[[NSBundle mainBundle] resourcePath ]stringByAppendingPathComponent:filename];
NSString *documentsFolder = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES)[0];
NSString *documentsPath = [documentsFolder stringByAppendingPathComponent:filename];
//NSString *dbPath = [[[NSBundle mainBundle] resourcePath ]stringByAppendingPathComponent:@"Milionar.sqlite"];
const char *sql = "INSERT INTO Scores(Points,Name) VALUES(?,?)";
if (![fileManager fileExistsAtPath:documentsPath])
{
BOOL success;
NSError *error = nil;
success = [fileManager copyItemAtPath:bundlePath toPath:documentsPath error:&error];
NSAssert(success, @"Unable to copy database: %@", error);
}
if(sqlite3_open([documentsPath UTF8String], &db) == SQLITE_OK)
{
sqlite3_stmt *sqlStatement;
if(sqlite3_prepare_v2(db, sql, -1, &sqlStatement, NULL) == SQLITE_OK)
{
sqlite3_bind_int(sqlStatement, 1, newScore.Points); //
sqlite3_bind_text(sqlStatement, 2, [newScore.Name UTF8String], -1, SQLITE_TRANSIENT); //
if (sqlite3_step(sqlStatement) != SQLITE_DONE)
{
NSLog(@"Error while updating. '%s'", sqlite3_errmsg(db));
}
sqlite3_finalize(sqlStatement);
}
else
{
NSLog(@"Problem with prepare statement");
}
}
else
{
NSLog(@"An error has occured while opening database.");
}
sqlite3_close(db);
}
}
@catch (NSException *exception) {
NSLog(@"An exception occured: %@", [exception reason]);
}
}
问题是在AddScore方法中,当我尝试检查数据库是否存在时,我得到false。但是当我不使用UIAlertView并且我用一些文本替换AddScore的调用警报时,我一切正常,并且保存了Score对象。问题出在哪里?为什么它在委托方法中不起作用?谢谢
CreateTableForScore 和 TableForScoresExists 都需要一个有效的数据库指针。
因此,在调用这两个属性中的任何一个之前,您需要先打开 db。
在当前的代码片段中,这两个函数都可能使用未初始化的数据库指针调用。
此外,如果您使用"CREATE TABLE IF NOT EXIST"(https://www.sqlite.org/lang_createtable.html),则不一定需要调用方法TableForScoresExists。这样可以节省一些代码。
您必须返回一个BOOL
但您有一个bool
。在 Obj-C 中,它们是不一样的。也许解决这个问题会有所帮助。
你确定这是正确的按钮索引吗?稍后在代码中调用[alert addButtonWithTitle:@"save"];
而不是调用 ShowMessageBoxForHighScore
,如果你只是调用它来测试这是否有效:
ListOfScores *listOfScores =[[ListOfScores alloc] init];
Score* score = [[Score alloc] initWithName:@"TestName" Points:10];
[listOfScores AddScore:score];
这可能有助于为您隔离问题。我的猜测是它可能与UIAlertView无关。